Mastering the BDS Ist Year (Last 25 Years Solved Questions) Hemant Gupta
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AnatomySECTION 1

Head, Neck and Brain
  1. Mandible
  2. Scalp
  3. Face
  4. Side of the Neck
  5. Anterior Triangle of Neck
  6. The Parotid Region
  7. Temporal and Infratemporal Region
  8. Submandibular Region
  9. Structures in the neck
  10. The Prevertebral and Paravertebral Region
  11. Back of the Neck
  12. The Cranial Cavity
  13. Contents of the Orbit
  14. The Mouth and Pharynx
  15. The Nose and Paranasal Sinuses
  16. Larynx
  17. The Tongue
  18. The Ear
  19. Miscellaneous
Functional Anatomy of Musculoskeletal System
  1. Skeleton
  2. Joints
  3. Circulatory System
Genetics
Neuroanatomy
  1. Introduction to Brain
  2. Meninges of the Brain and Cerebrospinal Fluid
  3. The Spinal Cord
  4. Cranial Nerves
  5. The Brainstem
  6. The Cerebellum
  7. The Fourth Ventricle
  8. Cerebrum
  9. The Third Ventricle, Lateral Ventricle and Limbic System
  10. Blood Supply of Spinal Cord and Brain
Upper Limb and Thorax
  1. Pectoral Region
  2. Axilla
  3. Scapular Region
  4. Cutaneous Nerves, Superficial Veins and Lymphatic Drainage
  5. Arm
  6. Bone and Joints of Thorax
  7. Wall of Thorax
  8. Thoracic Cavity and Pleurae
  9. Lungs
  10. Pericardium and Heart
  11. Trached, Esophagus and Thoracic Duct
Lower Limb, Abdomen and Pelvis
  1. Front of Thigh
  2. Popliteal Fossa
  3. Joints of Lower Limb
  4. Male External Genital Organs
  5. Abdominal Part of Esophagus and Stomach
  6. Kidney and Ureter
  7. Diaphragm
  8. Female Reproductive Organs
Fill in the Blanks as per DCI and Examination Papers of Various Universities
Image-Based Questions
Additional Matter2
3HEAD, NECK AND BRAIN
 
1. MANDIBLE
Q.1. Enumerate the nerves and vessels related to man-dible.
(Sep 2001, 4 Marks)
Ans. The nerves and vessels related to mandible are:
Enumeration of nerves and vessels of mandible
  • Mental nerve and vessels
  • Inferior alveolar nerve and vessels
  • Mylohyoid nerve and vessels
  • Lingual nerve
  • Masseteric nerve and vessels
  • Auriculotemporal nerve and superficial temporal artery
  • Facial artery
zoom view
Fig. 1: Nerves and vessels related to mandible
Q.2. Write a short note on age changes of mandible.
(Feb 1999, 4 Marks) (Apr 2010, 10 Marks)
Or
Write a short note on age related changes in mandible.
(Sep 2017, 3 Marks)
Ans. Age Changes of Mandible Are
  1. In infants and children:
    • Two halves of mandible fuse during the first year of life.
    • At birth, the mental foramen opens below the sockets of two deciduous molar teeth near lower border because bone is made up of only alveolar part with teeth sockets.
    • Mandibular canal runs near lower border.
    • The angle is obtuse, i.e. 140° or more because head of mandible is in the line of body. Coronoid process is large and project upward above the level of condyle.
  2. In adults:
    • Mental foramen opens midway between upper and lower borders because alveolar and subalveolar parts of bone are equally developed.
    • Mandibular canal runs parallel with mylohyoid line.
    • The angle reduces to about 110 or 120° because ramus is vertical.
  3. In old age:
    • Teeth exfoliate and alveolar border is absorbed, leading to reduction of height of body of mandible.
    • Mental foramen and mandibular canal are close to alveolar border.
    • The angle again becomes obtuse, i.e. 140° because the ramus is oblique.
zoom view
Figs 2A to C: Age changes in mandible. A. Infant, B. Adult, C. Old age
Q.3. Write a short note on general features of mandible.
(Sep 2006, 5 Marks)
Ans. Mandible has the following general features:
  1. Parts:
    1. Body: Part of mandible extending from the canine to the anterior border of masseter muscle.
    2. Ramus: Broad, superior, vertical extension from the posterior part of the body.
    3. Angle: Junction formed by the ramus and body of the mandible.
    4. Symphysis: Region corresponding to the midline of the mandible.
    5. Parasymphysis: Region adjacent to the symphysis.
  2. Processes:
    1. Condylar process: Rounded projection from the upper border of the ramus which articulates with the temporal bone to form the temporomandibular joint.
    2. Coronoid process: Sharp triangular projection from the upper border of the ramus that provides attachment to muscles of mastication.
    3. Alveolar process: Part of the mandible that bears the teeth.
  3. Ridges:
    1. External oblique ridge: Linear bony elevation crest on the lateral aspect of the mandible that 4extends from the first molar region and continues upward as the anterior border of the ramus.
    2. Internal oblique ridge: Linear bony elevation crest on the medial aspect of the mandible.
  4. Notches:
    1. Mandibular/sigmoid notch: The curvature or depression between the condyle and the coronoid processes.
    2. Coronoid notch: Depression/concavity on the anterior body of ramus.
  5. Foramina:
    1. Mental foramen: Present on the anterolateral aspect of the body of the mandible between the two premolars. Mental nerve and vessels pass through the foramen.
    2. Mandibular foramen: Present on the medial surface of the ramus. The inferior alveolar nerve and vessels are transmitted through the foramen.
  6. Fossae:
    1. Submandilbular fossa: Shallow depression present on the medial surface of the mandible to lodge the submandibular gland.
    2. Sublingual fossa: Shallow depression present on the medial surface of the mandible to lodge the sublingual gland.
    3. Digastric fossa: Depression on the lingual surface of mandible near the symphysis menti from where the anterior belly of digastric muscle originates.
  7. Tubercle:
    1. Genial tubercles: Small bony elevations that provide attachment to the geniohyoid and genioglossus muscles.
    2. Lingula: Lip-like projection on the medial surface of the mandible just above the mandibular foramen.
Q.4. Name the nerves related to mandible. Describe the movements of mandible.
(Sep 2006, 4 Marks) (Mar 2013, 4 Marks)
Or
Write short note on movements of mandible.
Ans. The nerves related to mandible are:
  1. Lingual nerve.
  2. Inferior alveolar nerve.
  3. Mylohyoid nerve.
  4. Mental nerve.
  5. Nerve to masseter.
  6. Auriculotemporal nerve.
 
Movements of Mandible
Muscles of the mastication causes the movements of mandible.
  1. Masseter muscle elevates the mandible to close the mouth.
  2. Temporalis elevates the mandible and posterior fibers of the muscle retract the protruded mandible.
  3. Lateral pterygoid muscle depresses the mandible to open the mouth.
  4. Medial pterygoid elevates the mandible and protrude the mandible.
  5. The medial and lateral pterygoid muscles of two sides contact alternately to protrude side to side movement of mandible.
Q.5. Write a short note on ossification of mandible.
(Apr 2007, 4 Marks)
Ans. Mandible is the second bone to ossify after the clavicle.
  • Greater part of the mandible ossifies in membrane.
  • Part which ossifies in cartilage is incisive part which lies below the incisor teeth. Condylar and coronoid processes, upper half of ramus above the level of mandibular foramen.
  • Each half of the mandible ossifies only from one center which appears at 6th week of intrauterine life in mesenchymal sheath of Meckle's cartilage near future mental foramen.
  • At birth mandible consists of two halves which is connected at symphysis menti by fibrous tissue. Bony union occurs during first year of life.
Q.6. Write short note on inferior alveolar nerve.
(Nov 2009, 5 Marks) (Jan 2012, 5 Marks)(Sep 2017, 3 Marks) (Dec 2014, 5 Marks)
 
Inferior Alveolar Nerve
  • It is the largest branch of mandibular nerve.
  • It descends medial or deep to lower head of lateral pterygoid muscle and lateraloposterior to lingual nerve to the region between sphenomandibular ligament and medial surface of ramus of mandible; where it enters mandibular canal at the level of mandibular foramen.
  • Throughout its path, it is accompanied by inferior alveolar artery (a branch of internal maxillary artery) and inferior alveolar vein. The artery lies just anterior to the nerve.
  • In the mandibular canal, the three structures together are referred to as “lnferior alveolar neurovascular bundle”.
  • It supplies the following structures:
    • Inferior portion of the ramus of the mandible
    • Entire body of the mandible
    • Pulps of the mandibular incisors, canines, premolars, and molars.
  • The nerve, artery and vein travel anteriorly in mandibular canal, as far forward as mental foramen which is located at a point below and between roots of the premolars where the nerve divides into its terminal branches
    • Mental nerve.
    • Incisive nerve.
    1. Mental nerve: It emerges from the mandibular canal through the mental foramen in the form of a major bulk and divides into three branches that innervate:
      1. Skin of chin,
      2. Skin and mucous membrane of lower lip, and
      3. Buccal mucosa from the incisor to the premolars. It carries a few secretomotor fibers from chorda tympani to labial minor salivary glands.
    2. 5Incisive nerve: It is the smaller terminal branch and the continuation of inferior alveolar nerve within the substance of the body of the mandible, anterior to the mental foramen.
      It supplies the pulps of anterior teeth, central and lateral incisors, and canine, and sometimes the first bicuspid, supporting alveolar bone, periodontal ligament, and the overlying soft tissues anterior to the mental foramen.
      It is commonly found that the mandibular central incisor has a dual nerve supply from the incisive nerve on its own side and from the terminal twigs of the incisive nerve of the opposite side.
Q.7. Write the name of various movements that the mandible undergoes.
(Oct 2016, 2 Marks)
Ans. Various movements which mandible undergoes are:
  • Protrusion
  • Retraction
  • Elevation
  • Depression
  • Lateral movements.
Q.8. Write short note on genial tubercle.
(Oct 2016, 3 Marks)
Or
Write very short answer on genial tubercles.
(Aug 2018, 2 Marks)
Ans. Genial tubercle is also known as mental spine.
Posterior surface of symphysis menti is marked by four small elevations known as inferior and superior genial tubercles.
Superior genial tubercles give origin to genioglossus muscle and inferior tubercles to geniohyoid muscle.
zoom view
Fig. 3: Genial tubercles
 
Relations
  • Mylohyoid line: It runs obliquely anterior and inferior, behind the 3rd molar tooth which is nearly 1 cm inferior to the alveolar border towards the symphysis menti below the genial tubercles.
  • Geniohyoid muscle: It originates from inferior genial tubercle.
  • Genioglossus muscle: It originates from superior genial tubercle.
Q.9. Write in short on pterygomandibular raphe.
(July 2016, 5 Marks)
Or
Answer in brief pterygomandibular raphe.
(Oct 2016, 2 Marks)
Ans. Pterygomandibular raphé (pterygomandibular ligament) is a tendinous band of the buccopharyngeal fascia, attached by one extremity to the hamulus of the medial pterygoid plate, and by the other to the posterior end of the mylohyoid line of the mandible.
Its medial surface is covered by the mucous membrane of the mouth.
Its lateral surface is separated from the ramus of mandible by a quantity of adipose tissue.
Its posterior border gives attachment to superior constrictor.
Its anterior border, to part of buccinator.
zoom view
Fig. 4: Pterygomandibular raphe
 
2. SCALP
Q.1. Describe various layers, innervations, venous drainage and arterial supply of scalp.
(Sep 2002, 10 Marks)
Or
Enumerate the layers of scalp.
(Aug 2018, 1 Mark)
Ans. Soft tissues covering the cranial vault form scalp.
 
Layers of Scalp
  • Skin
  • Superficial fascia
  • Deep fascia in the form of epicranial aponeurosis or galea aponeurotica with occipitofrontalis muscle
  • Loose areolar tissue
  • Pericranium6
zoom view
Fig. 5: Layers of scalp
Skin
  • It is thick and hairy.
  • Skin adheres to epicranial aponeurosis via the dense superficial fascia.
Superficial Fascia
  • This layer is more fibrous and is dense in center as compared to periphery at head.
  • Superficial fascia binds the skin to subjacent aponeurosis and provide proper medium for passage of vessels and nerves to the skin.
Galea Aponeurotica with Occipitofrontalis Muscle
  • This layer is freely movable on pericranium along with overlying and adherent skin and fascia.
  • Anteriorly the layer receives insertion of frontalis muscle, posteriorly it receives insertion of occipitalis muscle and the layer is attached to external occipital protuberance and to highest nucal lines in between occipital bellies.
  • On each side the layer is attached to superior temporal line, but sends down a thin expansion which passes over temporal fascia and attached to zygomatic arch.
  • Occipitofrontalis muscle consists of two bellies, i.e. occipital or occipitalis and frontal or frontalis. Both of the bellies are inserted in this layer.
  • Occipital bellies are small and separate. Each belli arises from lateral two-third of superior nuchal line and is supplied by posterior auricular branch of facial nerve.
  • Frontal bellies are longer and wider, they are partly united in the median plane. Each belly arises from the skin of forehead and mingle with obricularis oculi and corrugators supercilli. It is supplied by temporal branch of facial nerve.
Loose Areolar Tissue
  • Fourth layer is made up of loose areolar tissue.
  • This layer extends anteriorly into the eyelids, this is because frontalis has no bony attachment.
  • This layer provides passage to emissary veins which connect extracranial veins to intracranial venous sinuses.
Pericranium
  • This layer is the fifth layer of scalp.
  • This layer is loosely attached to surface of bone.
  • Pericranium is firmly attached to their sutures where the sutural ligaments bind pericranium to endocranium.
 
Innervation
Scalp is supplied by ten nerves on each side. Out of these five nerves (four sensory and one motor) enter the scalp in front of ear and other five behind the ear.
zoom view
Fig. 6: Innervation of scalp
 
A. Preauricular
  1. Sensory nerves:
    • Supratrochlear
    • Supraorbital
    • Zygomaticotemporal
    • Auriculotemporal.
  2. Motor nerve: Temporal branch of facial nerve.
 
B. Posterior Auricular
  1. Sensory nerve:
    • Posterior division of great auricular nerve
    • Lesser occipital nerve
    • Greater occipital nerve
    • Third occipital nerve.
  2. Motor nerve: Posterior auricular branch of facial nerve.
 
7Venous Drainage
  • Supratrochlear and supraorbital veins unite at medial angle of the eye and form angular vein which continues as facial vein.
zoom view
Fig. 7: Venous drainage of scalp
  • Superficial temporal vein descend in front of tragus, enters parotid gland and joins maxillary vein to form retromandibular vein. Retromandibular vein consists of two divisions, i.e.
    1. Anterior division of retromandibular vein unites with facial vein to form common facial vein which drains into internal jugular vein.
    2. Posterior division of retromandibular vein unites with posterior auricular vein and form external jugular vein which drains to subclavian vein. Occipital veins terminate in suboccipital venous plexus.
  • Emissary veins connect extracranial veins with intracranial venous sinuses to equalize pressure. Two of the emissary veins are present, i.e.
    1. Parietal emissary vein: It passes via parietal foramen to enter superior sagittal sinus.
    2. Mastoid emissary vein: It passes via mastoid foramen to reach sigmoid sinus.
  • Diploic veins: These veins start from cancellous bone inside the two tables of skull. There are four veins on each side, i.e.
    1. Frontal diploic vein: It emerges at supraorbital notch and open in supraorbital vein.
    2. Anterior temporal diploic vein: It ends in anterior deep temporal vein or sphenoparietal sinus.
    3. Posterior temporal diploic vein: It ends in transverse sinus.
    4. Occipital diploic vein: It opens either in occipital vein, or into transverse sinus near median plane.
 
Arterial Supply
Two set of arteries five on each side, out of these five arteries, three arteries lie in front of ear and two behind the ear.
 
Arteries
Preauricular
  1. Supratrochlear
  2. Supraorbital
  3. Superficial temporal arteries
    Out of these arteries 1st and 2nd are the branches of ophthalmic branch of internal carotid artery. The third artery is branch of the external carotid artery.
Posterior Auricular
Behind the ear there is posterior auricular artery. One more artery which is in the occipital region is known as occipital artery. These two arteries are branches of external carotid artery.
zoom view
Fig. 8: Nerve supply and arterial supply of scalp
8Q.2. Enumerate various layers in scalp. Give its blood supply, nervous supply and lymphatic drainage.
(March 2000, 12 Marks) (Apr 2010, 10 Marks)
Ans. Various layers of scalp, blood supply, nervous supply and lymphatic drainage are given in Ans 1 of the same chapter.
 
Lymphatic Drainage
  • Preauricular: Lymph from anterior part of scalp is drained into parotid group of lymph nodes.
  • Postauricular: Lymph from posterior part of scalp is collected by lymph nodes present in mastoid area and occipital area which are known as mastoid and occipital group of lymph nodes.
Q.3. Write a short note on arterial supply of scalp.
(Sep 2004, 5 Marks)
Or
Write a short answer on arterial supply of scalp.
(Apr 2018, 3 Marks)
Ans. Refer to Ans 1 of same chapter.
Q.4. Write applied anatomy of scalp.
(June 2010, 5 Marks) (Aug 2011, 5 Marks)
Or
Describe scalp with its applied anatomy.
(May 2014, 10 Marks)
Or
Write in brief on applied anatomy of scalp.
(Sep 2015, 5 Marks)
Or
Describe scalp with its applied aspects.
(Sep 2017, 10 Marks)
Or
Write a short note on applied aspect of scalp.
(Jan 2018, 5 Marks)
Ans. Description is given in Ans 1 and 2.
 
Applied Anatomy of Scalp
  • Due to abundance of sebaceous glands, scalp is common site for sebaceous cysts.
  • Wounds present on scalp bleeds profusely, this is because the vessels are prevented from retracting fibrous fascia. Arresting of bleeding is done by applying pressure above the ears by tight cotton bandage against bone.
  • Due to density of fascia, subcutaneous hemorrhages are not extensive, inflammation in this layer leads to little swelling but more pain.
  • Since pericranium is attached to the sutures, collection of fluid deep to pericranium is called as cephalhematoma, which take the shape of bone concerned.
  • Dangerous area of scalp: Layer of loose areolar tissue is known as dangerous area of scalp because emissary veins which course from here can transmit infection from scalp to cranial venous sinuses.
  • Black eye: As blood is collected in layer of loose connective tissue, it leads to generalized swelling of scalp. Blood can extend anteriorly into the roof of nose and into the eyelids, since frontalis muscle has no bony attachment this causes black eye. Posterior limit of hemorrhage is not seen when injury to scalp occur, it can only be seen when bleeding is due to local injury.
  • Caput succidaneum: At the time of delivery during obstructed labor there may be collection of blood or serum in this layer causing oversized head.
  • Safety valve hematoma: When there is intracranial hemorrhage. It causes increase in intracranial pressure and may harm the brain. Due to venous communication the blood from inside comes out and rest in this space and this blood does not enter back.
  • Cephalohydrocele: The collection of cerebrospinal fluid in this layer is known as cephalohydrocele. It is common in children.
Q.5. Describe scalp under the following headings:
(Sep 2006, 15 Marks)
a. Structure
b. Nerve supply
c. Applied anatomy
Ans. For structure and nerve supply refer to Ans 1 of the same chapter.
For applied anatomy refer to Ans 4 of the same chapter.
Q.6. Draw diagram of layers of scalp.
(Apr 2007, 5 Marks)
Or
Draw and label layers of scalp.
(Apr 2015, 3 Marks)
Ans.
zoom view
Fig. 9: Layers of scalp
9Q.7. Write a short note on dangerous area of scalp.
(Jan 2012, 4 Marks) (Aug 2012, 4 Marks)
Or
Give explanation about dangerous area of scalp.
(Feb 2013, 2 Marks) (Mar 2009, 5 Marks)(Jan 2012, 5 Marks)
 
Dangerous Area of Scalp
The subaponeurotic layer (fourth layer) forms a potential space filled with loose areolar tissue beneath the aponeurotic layer. The emissary veins which communicate the veins of the scalp with the intracranial venous sinuses, pass through this space. This space is closed on all sides except anteriorly where it extends into the upper eyelid. It is known as the dangerous area of scalp.
zoom view
Fig. 10: Dangerous area of scalp
 
Clinical Significance
  • Fluid collected in this space tends to gravitate in the eyelid. In this way black eye is produced if there is bleeding in this space due to scalp injury on direct blow to the skull. The infection in this space readily enters the cranium through the emissary veins causing thrombosis of the venous sinuses or osteomyelitis of the cranial bones.
  • In newborn babies, there is slow accumulation of blood in this space, when there is intracranial hemorrhage due to fracture of bone of the vault and associated dural tear. The leakage of blood outside the cranium in the potentially large subaponeurotic space delays the symptom of cerebral compression. Hence, the slow accumulation of blood in the fourth layer is known as safety valve hematoma.
Q.8. Write short note on blood and nerve supply of scalp.
(Aug 2011, 5 Marks)
Ans. Refer to Ans 1 of the same chapter.
Q.9. Write short note on layers of scalp.
(Mar 2013, 3 Marks)
Or
Write short answer on layers of scalp.
(Apr 2018, 3 Marks)
Ans. Refer to Ans 1 of the same chapter.
Q.10. Describe blood supply, nerve supply and applied anatomy of scalp.
(Apr 2016, 15 Marks)(Dec 2014, 10 Marks)
Ans. For blood supply and nerve supply refer to Ans 1 and for applied anatomy refer to Ans 4 of same chapter.
Q.11. Draw a diagram of scalp to show the blood supply and nerve supply.
(July 2016, 10 Marks)
Or
Draw a well labeled diagram to show the blood vessels and nerves supplying the scalp.
(Oct 2016, 5 Marks)
Ans. For diagram of venous drainage of scalp refer to Ans 1 of same chapter.
zoom view
Fig. 11: Arterial supply and nerve supply of scalp
10Q.12. Enumerate layers of scalp.
(May 2017, 3 Marks)
Ans. Following are the layers of scalp:
  • Skin
  • Superficial fascia
  • Deep fascia in the form of epicranial aponeurosis or Galea aponeurotica with occipitofrontalis muscle
  • Loose areolar tissue
  • Pericranium
Q.13. Answer in brief on black eye.
(May 2017, 3 Marks)
Ans. As blood is collected in layer of loose connective tissue, it leads to generalized swelling of scalp. Blood can extend anteriorly into the roof of nose and into the eyelids, since frontalis muscle has no bony attachment this causes black eye. Posterior limit of hemorrhage is not seen when injury to scalp occur, it can only be seen when bleeding is due to local injury.
zoom view
Fig. 12: Right eye—black eye due to injury to the scalp; left eye—black eye due to local injury
  • In right eye, black eye occur due to injury to scalp.
  • In left eye, black eye is due to local injury.
Q.14. Answer in brief on emissary vein.
(May 2017, 3 Marks)
Ans. The veins connecting the veins outside the cranium with the intracranial dural venous sinuses by passing through foramina in the cranium are called emissary veins.
Emissary vein connect pterygoid venous plexus to the cavernous sinus.
 
Emissary Veins in the Region of the Scalp
On each side of the midline in the region of the scalp two sets of emissary veins are encountered, viz.
  1. Parietal emissary vein, which passes through parietal foramen and communicates with the superior sagittal sinus.
  2. Mastoid emissary vein, which passes through mastoid foramen and communicates with the sigmoid sinus.
 
Emissary Veins of Skull
Name of emissary vein
Foramen of skull
Veins outside skull
Venous sinuses
Parietal emissary vein
Parietal foramen
Veins of scalp
Superior saggittal venous sinus
Mastoid emissary vein
Mastoid foramen
Veins of scalp
Sigmoid sinus
Emissary vein
Hypoglossal canal
Internal jugular vein
Sigmoid sinus
Condylar emissary vein
Posterior condylar foramen
Suboccipital venous plexus
Sigmoid sinus
2 to 3 emissary veins
Foramen lacerum
Pharyngeal venous plexus
Cavernous sinus
Emissary vein
Foramen ovale
Pterygoid venous plexus
Cavernous sinus
Emissary vein
Foramen cecum
Veins of roof of nose
Superior saggittal venous sinus
 
3. FACE
Q.1. Write a short note on nerve supply of face.
(May/June 2009, 5 Marks)
Or
Write a short answer on nerve supply of face.
(Apr 2018, 3 Marks)
Ans. Nerve supply of face.
 
Sensory Nerve Supply
  • Ophthalmic divisions of trigeminal nerve:
    • Supratrochlear
    • Supraorbital
    • Lacrimal
    • Infratrochlear
    • External nasal.
zoom view
Fig. 13: Sensory supply of face
  • Maxillary division of trigeminal nerve:
    • Infraorbital
    • Zygomaticofacial
    • Zygomaticotemporal.
  • 11Mandibular division of trigeminal nerve:
    • Auricular temporal
    • Buccal nerve
    • Mental nerve.
  • Cervical plexus:
    • Anterior division of greater auricular nerve
    • Upper division of transverse cutaneous nerve of neck.
Sensory Nerve Supply
All these above mentioned nerves have following areas of distribution:
Name of the nerve
Area of distribution
Ophthalmic division of trigeminal nerve
Supratrochlear nerve
Upper eyelid and forehead
Supraorbital nerve
Upper eyelid, frontal air sinus, scalp
Lacrimal nerve
Lateral part of upper eyelid
Infratrochlear
Medial part of both eyelids
External nasal
Lower part of dorsum and tip of nose
Maxillary division of trigeminal nerve
Infraorbital nerve
Lower eyelid, side of nose and upper lip
Zygomaticofacial nerve
Upper part of cheek
Zygomaticotemporal nerve
Anterior part of temporal region
Mandibular division of trigeminal nerve
Auriculotemporal nerve
Upper two-third of lateral side of auricle, temporal region
Buccal nerve
Skin of lower part of cheek
Mental nerve
Skin over chin
Cervical plexus
Anterior division of great auricular nerve
Skin over angle of jaw and parotid gland
Upper division of transverse cutaneous nerve of neck
Lower margin of lower jaw
 
Motor Nerve Supply
Motor supply of face is obtained through facial nerve. It emerges from substance of parotid gland and divide into following branches:
  • Temporal branch
  • Zygomatic branch
  • Buccal branch
  • Marginal mandibular branch
  • Cervical branch.
Motor Nerve Supply
These terminal branches supplies to following muscles:
Name of the nerve
Muscles supplied
Temporal
Frontalis, auricular muscle, orbicularis oris
Zygomatic
Orbicularis oculi
Buccal
Muscles of cheek and upper lip
Marginal mandibular
Muscles of lower lip
Cervical
Platysma muscle
Q.2. Describe sensory innervation of face.
(Sep 2000, 4 Marks) (Dec 2009, 5 Marks)
Or
Describe in brief sensory nerve supply of face.
(Sep 2007, 4 Marks) (Mar 2008, 3 Marks)
Or
Write a short note on sensory supply of face.
(Feb 2016, 3 Marks)
Or
Answer in brief sensory supply of face (diagram only).
(Feb 2016, 2 Marks)
Ans. Refer to Ans 1 of the same chapter.
Q.3. Write a short note on blood supply of face.
(Mar 2009, 5 Marks)
Ans.
 
Blood Supply of the Face
Arterial Supply
It is supplied by:
  • Facial artery
  • The transverse facial artery
  • Arteries that accompany cutaneous nerves.
These are the small branches of ophthalmic maxillary and superficial temporal arteries.
zoom view
Fig. 14: Arteries supply of face
Venous Drainage
Venous blood from face is drained by two veins, i.e. facial vein and retromandibular vein
  1. Facial vein: This is the largest vein of face. This is formed at medial angle of eye by union of supratrochlear and supraorbital veins. As it is formed, it runs straight downward and backward behind facial artery to reach anteroinferior angle of massater. Here it pierces deep 12fascia, crosses superficial to submandibular gland and join anterior division of retromandibular vein below angle of mandible to form common facial vein which drains to internal jugular vein. Tributaries of facial vein correspond to branches of facial artery.
    Deep connections of facial vein
    • A communication between the supraorbital and superior ophthalmic vein.
    • Another connection with the pterygoid plexus through the deep facial vein which passes backward over the buccinator deep to ramus of mandible and communicate with pterygoid venous plexus around lateral pterygoid muscle which communicate with cavernous sinus via emissary vein.
  2. Retromandibular vein: It is formed by union of superficial temporal and maxillary vein within parotid gland. On leaving parotid gland, it is divided into two divisions, i.e. anterior and posterior. Anterior division joins facial vein to form common facial vein, while posterior division joins posterior auricular vein to form external jugular vein.
zoom view
Fig. 15: Venous drainage of face
Q.4. Write a short note on facial artery.
(July 2016, 5 Marks)
(June 2010, 5 Marks) (Jan 2012, 5 Marks)
(Apr 2017, 4 Marks) (Jan 2018, 5 Marks)
Or
Write a short note on facial artery in the face.
(Aug 2016, 3 Marks)
Or
Write short answer on facial artery.
(Aug 2018, 3 Marks)
Ans. Facial Artery
Introduction: Facial artery is the chief artery of face. It is a branch of external carotid artery which is given off in carotid triangle just above the tip of greater cornue of hyoid bone. It runs upwards and crosses its passage in cervical region in order to reach the face.
 
Course of Facial Artery
  • Facial artery enters the face by winding around the base of mandible and by piercing the deep cervical fascia at anteroinferior angle of massater muscle.
  • First the artery run forward and upward to a point 1.25 cm lateral to angle of mouth. Now the artery ascends by the side of nose till medial angle of an eye where it terminates by supplying lacrimal sac and by anastomosing with dorsal nasal branch of ophthalmic artery.
  • Facial artery is tortuous and it lies between the superficial and deep muscles of the face.
zoom view
Fig. 16: Course of facial artery
 
Branches of Facial Artery
The large anterior branches are:
  1. Inferior labial: To lower lip
  2. Superior labial: To upper lip and anteroinferior part of nasal septum
  3. Lateral nasal: To ala and dorsum of nose
  4. Branch to lacrimal sac.
 
Anastomosis
  1. The large anterior branches anastomose with arteries of same name on opposite side and with mental artery.
  2. The posterior branches anastomosis with infraorbital artery and transverse facial artery.
  3. At medial angle of eye, terminal branches anastomose with branches of ophthalmic artery. So this is a site of anastomosis between external and internal carotid arteries.
Q.5. Write a short note on lymphatic drainage of face.
(Sep 1999, 4 Marks)
13Ans. Lymphatic Drainage of Face
This is divided into three groups.
  1. Upper territory: It drains into preauricular parotid group of lymph nodes. It drains greater part of forehead, lateral half of eyelids, conjunctiva, lateral part of cheek and parotid area.
  2. Middle territory: It drains into submandibular lymph nodes. It drains the median part of forehead, external nose, upper lip, medial halves of eyelids, medial part of cheek and greater part of lower jaw.
  3. Lower territory: It drains into submental group of lymph nodes from area which includes central part of lower lip and chin.
zoom view
Fig. 17: Lymphatic drainage of face
zoom view
Fig. 18: Lymphatic drainage of face
Q.6. Write a note on dangerous area of face.
(Sep 2002, 5 Marks) (Sep 2001, 6 Marks)
Or
Write a short note on dangerous area of face.
(Oct 2007, 5 Marks) (Dec 2010, 5 Marks)(Dec 2009, 5 Marks) (Sep 2013, 5 Marks)
(Sep 2017, 2 Marks)
zoom view
Fig. 19: Dangerous area of face
Ans. Dangerous Area of Face
Facial vein communicates with the cavernous sinus via emissary veins, through these connection infection from the face can spread in retrograde direction and causes thrombosis of cavernous sinus. This is specially likely to occur in presence of infection in upper lip and in lower part of nose. Hence, the area is known as the “Dangerous area of the face.”
As facial veins and its deep connecting veins are devoid of valves which provide an uninterrupted passage of blood to cavernous sinus. So, squeezing the pustules or pimples in the area of upper lip or side of nose or side of cheeks can lead to infection which may be carried to cavernous sinus leading to cavernous sinus thrombosis.
Q.7. Write a short note on extracranial course of facial nerve.
(Feb 1999, 4 Marks) (Mar 2008, 4 Marks)(Oct 2014, 3 Marks)
Or
Write a short note on extracranial part of facial nerve.
(Sep 2004, 10 Marks)
Or
Write note on extracranial course of facial nerve.
(Apr 2008, 4 Marks) (Mar 2008, 4 Marks)
Or
Describe in detail the extracranial course of facial nerve.
(Mar 2008, 8 Marks) (Apr 2010, 5 Marks)
Or
Write on extracranial course and branches of facial nerve.
(Mar 2013, 4 Marks)
14Ans. Extracranial Course of Facial Nerve
In its extracranial course the facial nerve crosses the lateral side of base of styloid process. It enters the posteromedial surface of parotid gland, runs forward through the gland crossing the retromandibular vein and external carotid artery. Behind the neck of mandible it divides into its five terminal branches which emerge along anterior border of parotid gland.
zoom view
Fig. 20: Course of facial nerve
 
Branches of Facial Nerve
  1. Greater petrosal nerve: It arises from the geniculate ganglion and leaves the middle ear through tegmen tympani. It joins with the deep petrosal nerve to form nerve to pterygoid canal. This nerve conveys preganglionic secretomotor fibers to the lacrimal gland and nasal mucosa. They relay in the pterygopalatine ganglion.
  2. A twig from geniculate ganglion joins the lesser petrosal nerve.
  3. Nerve to stapedius: This arises in the facial canal behind the middle ear and runs forward through a short canal to reach and supply the stapedius muscle.
  4. Chorda tympani nerve: It arises in the facial canal about 6 mm above the stylomastoid foramen and enters the middle ear. It passes forward across the inner surface of the tympanic membrane internal to the handle of malleus and then leaves the middle ear by passing through the petrotympanic fissure to appear at the base of skull. Here it runs downwards and forwards in the infratemporal fossa and joins the lingual nerve at an acute angle. The chorda tympani nerve carries:
    1. Taste fibers from anterior 2/3rd of the tongue, except from vallate papillae
    2. Secretomotor fibers to the submandibular and sublingual salivary glands.
  5. Posterior auricular nerve: It arises just below the styloid foramen. It further divides into two branches, i.e.
    1. Auricular branch, which supplies the muscles of auricle.
    2. Occipital branch, which supplies the occipital belly of the occipito-frontalis.
  6. Nerve to posterior belly of digastric: It arises near the origin of posterior auricular nerve and supplies the posterior belly of digastric. It also gives a branch to the stylohyoid muscle.
  7. Terminal branches: They are 5 in number and arise within the parotid gland. From above downwards they are:
    1. Temporal branch: It runs across the zygomatic arch and supplies the muscles of the ear, frontal belly of occipital frontalis and corrugator supercilii.
    2. Zygomatic branch: It runs below and parallel to the zygoma and supplies the orbicularis oculi.
    3. Buccal branches: These are usually two in number. The upper one supplies zygomaticus major, zygomaticus minor and levators of the upper lip. The lower one supplies the buccinator and orbicularis oris.
    4. Marginal mandibular branch: This first run downwards and forward below the angle of the mandible and then curves upwards across the base of the mandible to supply the muscles of the lower lip and chin.
    5. Cervical branch: It passes downwards and forward to the front of the neck and supplies the platysma.
  8. Communicating branches: It communicates with the following neighboring nerves at various sites.
    1. Vestibulo-cochIear nerve, at the internal acoustic meatus
    2. Sympathetic plexus around middle meningeal artery at geniculate ganglion
    3. Auricular branch of vagus nerve in the facial canal
    4. 9th and 10th cranial nerves, below the stylomastoid foramen
    5. Lesser occipital nerve behind the ear
    6. Branches of trigeminal nerve in the face.
Q.8. Write a short note on buccinator muscle.
(Oct 2007, 5 Marks) (Dec 2010, 5 Marks)
Or
Write short note on origin, insertion, nerve supply and action of buccinator muscle.
(Oct 2016, 3 Marks)
Ans.
Buccinator muscle–muscle of cheek
Origin
  • Upper fibers: From maxilla opposite to molar teeth
  • Lower fibers: From mandible opposite to molar teeth
  • Middle fibers: From pterygomandibular raphe
Insertion
  • Upper fibers: Straight to upper lip
  • Lower fibers: Straight to lower lip
  • Middle fibers: Middle fibers decussate
Nerve supply
Lower buccal branches of facial nerve
Action
  • Puffing of the mouth and blowing
  • Flattens cheek against gums and teeth
  • Prevents accumulation of food inside the vestibule
15
zoom view
Fig. 21: Buccinator muscle
Q.9. Write extracranial course of facial nerve and write its branches and applied anatomy.
(Feb 2004, 15 Marks)
Or
Give an account of extracranial course of facial nerve. Name its branches and applied anatomy.
(Feb 2005, 8 Marks)
Or
Describe the extracranial course and branches of facial nerve. Add a note on its applied anatomy.
(March 2007, 8 Marks) (Sep 2007, 3 + 1 = 4 Marks)
Or
Describe facial nerve and its applied part.
(June 2010, 15 Marks)
Ans. The extracranial course of facial nerve and branches are given in Ans 7 of the same chapter.
 
Applied Anatomy
Facial Palsy
It is the paralysis of the facial nerve. It is of two types:
  1. Upper motor neuron type
  2. Lower motor neuron type.
Upper Motor Neuron Facial Palsy
It is due to involvement of the corticonuclear fibers, i.e. the upper motor neurons. These fibers arise in the cerebral cortex, pass through internal capsule and end in the motor nucleus of the facial nerve. These are most commonly involved in patients with cerebral hemorrhage which is always associated with hemiplegla. Since the lesion is above the nucleus, it is also called as supranuclear type of facial palsy. It leads to paralysis of the contralateral lower part of face below the palpebral fissure.
Lower Motor Neuron Facial Palsy
It is further of 2 types
  1. Nuclear paralysis: It is due to involvement of the nucleus of facial nerve. This can occur due to poliomyelitis or lesions of the pons. The motor nucleus of facial nerve is close to the abducent nerve which is also usually affected.
    Effect: Paralysis of muscles of the entire face on ipsilateral side.
  2. Infranuclear paralysis: This occurs due to involvement of the facial nerve. Clinical effects vary according to the site of injury of the nerve.
    Facial nerve can get injured at various sites.
    • Site A: At or just above the stylomastoid foramen: It leads to Bell's palsy which presents as loss of motor functions of all muscles of facial expression leading to the deviation of mouth toward the normal side, inability to close the mouth and eye and accumulation of food in the vestibule of mouth, flattening of expression lines, etc.
    • Site B: Above the origin of chorda tympani: All the signs and symptoms of lesion A (i.e. Bell's palsy) along with decreased salivation and loss of taste sensation in the anterior two-third of the tongue.
    • Site C: Above the origin of nerve to stapedius: All the signs and symptoms of lesion B along with hyperacusis (i.e. enhanced sensitivity to hearing).
    • Site D: At the geniculate ganglion: All the signs and symptoms of lesion C along with loss of lacrimation.
Bell's Palsy
Bell's palsy is a lower motor neuron type of facial nerve involvement. It leads to paralysis of muscles of facial expression. There may be associated symptoms according to the site of lesion. Facial muscles of the same side are paralysed and this leads to the following features:
  1. Facial asymmetry — due to unopposed action of muscles of the normal side. There is deviation of angle of mouth to the opposite side.
  2. Loss of wrinkles on forehead—due to paralysis of fronto-occipitalis muscle.
  3. Widening of palpebral fissure and inability to close the eye—due to paralysis of orbicularis oculi.
  4. Inability of angle of mouth to move upwards and laterally during laughing — due to paralysis of zygomaticus major.
  5. Loss of nasolabial furrow — due to paralysis of levator labi, superioris alaeque nasi.
  6. Accumulation of food into the vestibule of mouth — due to paralysis of buccinator muscle.
  7. Dribbling of saliva from the angle of mouth — due to paralysis of orbicularis oris.
  8. When one presses the cheek with inflated vestibule, the air leaks out between the lips — due to paralysis of orbicularis oris.
  9. Loss of resistance while blowing out air in mouth — due to paralysis of buccinator muscle.
 
16Crocodile Tear Syndrome
Lacrimation during eating occurs because of aberrant regeneration after trauma. This is crocodile tear syndrome. In case of damage to the facial nerve proximal to geniculate ganglia, regenerating fibers for submandibular salivary gland grow in an endoneural sheath of preganglionic secretomotor fibers supplying the lacrimal gland. Due to this patient lacrimates during eating.
 
Ramsay–Hunt Syndrome
Involvement of geniculate ganglia by herpes zoster leads to this syndrome.
The syndrome consists of hyperacusis, loss of lacrimation, loss of sensation of taste in anterior two-third of tongue, Bell's palsy and lack of salivation, vesicles on an auricle.
Q.10. Write a short note on venous drainage of face.
(Sep 2005, 5 Marks)
Ans. Refer to Ans 3 of the same chapter.
Q.11. Describe various drainage of face.
(Aug 2005, 15 Marks)
Ans. For arterial supply and venous drainage refer to Ans 3 of the same chapter and for lymphatic drainage refer to Ans 5 of the same chapter.
Q.12. Describe venous drainage of face. Add a note on dangerous area of face.
(Sep 2006, 10 Marks)
Ans. For venous drainage refer to Ans 3 of the same chapter. For dangerous area of face refer to Ans 6 of the same chapter.
Q.13. Classify and name the muscles of facial expression. Add a note on Bell's palsy.
(Mar 2006, 10 Marks)
Ans. Classification and Names of Facial Muscles
  1. Muscles of scalp
    1. Occipitofrontalis.
  2. Muscles of the auricle
    1. Auricularis anterior
    2. Auricularis superior
    3. Auricularis posterior.
    zoom view
    Fig. 22: Muscles of scalp and auricle
  3. Muscles of the eyelid
    1. Orbicularis oculi
    2. Corrugator supercilli
    3. Levator palpebrae superioris.
  4. Muscles of the nose
    1. Procerus
    2. Compressor naris
    3. Dilator naris
    4. Depressor septi.
    zoom view
    Fig. 23: Muscles of eyelid and nose
  5. Muscles around the mouth
    1. Orbicularis oris
    2. Levator labii superioris alaeque nasi
    3. Levator labii superioris
    4. Levator anguli oris
    5. Zygomaticus major
    6. Zygomaticus minor
    7. Depressor anguli oris
    8. Depressor labii inferioris
    9. Mentalis
    10. Risorius
    11. Buccinator.
  6. Muscles of the neck
    1. Platysma.
For Bell's palsy refer to Ans 9 of the same chapter.
zoom view
Fig. 24: Muscles of mouth and neck
Q.14. Draw a diagram of muscle attachment of hyoid bone.
(Apr 2007, 4 Marks)
17Ans.
zoom view
Fig. 25: Muscle attachment of hyoid bone
Q.15. Write a short note on facial palsy.
(Apr 2008, 3 Marks)
Ans. Refer to Ans 9 of the same chapter.
Q.16. Describe facial nerve under following headings:
(Dec 2010, 3+3+2 Marks)
a. Nuclei and course of nerve
b. Branches
c. Bell's palsy
Ans. Nuclei of Facial Nerve
Fibers of the nerve arise from four nuclei situated in the lower pons.
  1. Motor nucleus (branchiomotor).
  2. Superior salivatory nucleus (parasympathetic).
  3. Lacrimatory nucleus (parasympathetic).
  4. Nucleus of the tractus solitarius (gustatory).
Motor nucleus lies deep in the reticular formation of the lower pons. The part of the nucleus that supplies muscles of the upper part of the face receives corticonuclear fibers from the motor cortex of both right and left sides.
In contrast the part of the nucleus supplies muscles of the lower part of the face receive corticonuclear fibers only from the opposite cerebral hemisphere.
 
Course of Facial Nerve
Intracranial Course
Facial nerve is attached to brainstem by two roots, i.e. motor and sensory. Sensory root is known as nervus intermedius. Two roots of facial nerve are attached to lateral part of lower border of pons medial to vestibulocochlear nerve. Two roots run laterally and forward along with vestibulocochlear nerve to reach internal acoustic meatus.
zoom view
Fig. 26: Facial nerve and its distribution
18In internal acoustic meatus motor root lies in groove on vestibulocochlear nerve with sensory root intervening. Here facial nerve and vestibulocochlear nerve are accompanied by labyrinthine vessels. At fundus of meatus the two roots sensory and motor fuse to form a single trunk which lies in petrous temporal bone. Within the canal the course of nerve is divided by three parts by two of its bands.
The first part is directed laterally above the vestibule and second part run backward in relation to medial wall of middle ear above promontory and third part is directed vertically downward behind promontory. First bend at junction of first and second part is sharp and is known as genu.
Second bend lies between promontory and aditus to the mastoid antrum. Facial nerve leaves the skull by passing through stylomatoid foramen.
Extracranial Course
Refer to Ans 7 of the same chapter.
For branches of facial nerve refer to Ans 7 of the same chapter.
For Bell's palsy refer to Ans 9 of the same chapter.
Q.17. Enumerate extracranial branches of facial nerve.
(Jan 2012, 2 Marks)
Ans. The extracranial branches of facial nerve are:
  1. Temporal
  2. Zygomatic
  3. Buccal
  4. Marginal mandibular
  5. Cervical.
Q.18. Write briefly on bell's palsy.
(Aug 2012, 5 Marks) (Apr 2007, 5 Marks)
Or
Write short note on bell's palsy.
(Jan 2018, 5 Marks)
(Feb 2013, 5 Marks) (Feb 2016, 3 Marks)
Ans. Refer to Ans 9 of the same chapter.
Q.19. Describe lacrimal apparatus and its nerve supply.
(Feb 2014, 4 Marks)
Or
Describe briefly lacrimal gland and its nerve supply.
(Nov 2008, 5 Marks)
Ans. Structures which are related to the secretion and drainage of lacrimal gland forms the lacrimal apparatus.
Lacrimal apparatus constitutes following parts, i.e.
  1. Lacrimal gland and its ducts
  2. Conjunctival sac
  3. Lacrimal puncta and lacrimal canaliculi
  4. Lacrimal sac
  5. Nasolacrimal duct.
 
Lacrimal Gland
  • Lacrimal gland is a serous gland which is situated chiefly in lacrimal fossa on anterolateral part of roof of bony orbit and partly on the upper eyelid.
  • Small accessory lacrimal glands are found in conjunctival fornices.
  • It is of J shaped and is indented by the tendon of levator palpabrae superioris.
  • It consists of two parts, i.e.
    1. An orbital part: It is large and deeper
    2. A palpebral part: It is superficial and smaller lying within the eyelid.
  • Lacrimal gland consists of a dozen of ducts which pierce conjunctiva of upper eyelid and open in conjunctival sac near superior fornix.
  • Most of the ducts of orbital part pass through palpebral part.
  • It is supplied by lacrimal branch of ophthalmic artery.
  • It secretes lacrimal fluid which flows in conjunctival sac where it lubricate the front of eye and deep surface of eyelids.
zoom view
Fig. 27: Lacrimal apparatus
 
Conjunctival Sac
  • Conjunctiva lining the deep surface of eyelids is known as palpebral conjunctiva and which lines the front of eyeball is bulbar eyeball.
  • Potential space between palpebral and bulbar part is conjunctival sac.
  • Lines at which the palpaberal conjunctiva of upper and lower eyelids is reflected on eyeball are known as superior and inferior conjunctival fornices.
  • Palpebral conjunctiva is opaque, thick and is vascular.
  • Bulbar conjunctiva covers the sclera and is thin, transparent and is loosely attached to eyeball.
 
Lacrimal Puncta and Canaliculi
  • Each single lacrimal canaliculus starts at the lacrimal punctum.
  • It is 10 mm long.
  • A dilated ampulla is present at the bend.
 
19Lacrimal Sac
  • It is a membranous sac and is situated in lacrimal groove behind the medial palpebral ligament.
  • Upper end of lacrimal sac is blind and lower end is continuous with nasolacrimal duct.
 
Nasolacrimal Duct
  • Nasolacrimal duct is a membranous passage and is 18 mm long.
  • It starts from lower end of lacrimal sac and run downward, backward and laterally and opens in inferior meatus of nose.
  • Valve of Hasner, i.e. a fold of mucous membrane form an imperfect valve at lower end of duct.
 
Nerve Supply of Lacrimal Apparatus
  1. Sensory: Sensory supply is by lacrimal branch of ophthalmic division of trigeminal nerve.
  2. Sympathetic:
    1. Preganglionic fibers arise from T1 spinal segment of spinal cord to superior cervical sympathetic ganglion.
    2. Postganglionic fibers are the sympathetic plexus around internal carotid artery to deep petrosal nerve, pterygopalatine ganglion zygomatic nerve, zygomaticotemporal nerve to lacrimal nerve to lacrimal gland.
  3. Parasympathetic nerve: It carries secretomotor fibers.
    1. Preganglionic fibers arise from lacrimatory nucleus and via facial nerve goes to greater petrosal nerve and join deep petrosal nerve to form nerve to pterygoid canal and reaches to pterygopalatine ganglion for relay.
    2. Postganglionic fibers arise from cell of pterygopalatine ganglion and passes successively via maxillary nerve, zygomatic nerve, zygomaticotemporal branch of maxillary nerve to lacrimal nerve and from lacrimal nerve to lacrimal gland.
zoom view
Fig. 28: Nerve supply of lacrimal apparatus
Q.20. Write a short note on chorda tympani nerve.
(May 2014, 5 Marks)
(Apr 2017, 4 Marks) (May 2017, 3 Marks)
Or
Write in brief on chorda tympani nerve.
(Sep 2015, 5 Marks)
Or
Answer in brief on chorda tympani nerve.
(Oct 2016, 2 Marks)
Ans. Chorda tympani is the sensory nerve. Chorda tympani nerve is so called because it has intimate relationship with middle ear.
 
Functional Components
The nerve consists of:
  • General visceral efferent fibers: They are preganglionic parasympathetic or secretomotor fibers to submandibular and sublingual salivary gland.
  • Special visceral afferent fibers: They carry taste sensations from anterior 2/3rd of tongue.
 
Origin, Course and Relations
Chorda tympani nerve arises from facial nerve in the facial canal at about 6 mm above the stylomastoid foramen within the posterior wall of the tympanic (middle ear) cavity. It enters the middle ear through the posterior canaliculus of chorda tvmpani in the posterior wall, runs across the lateral 20wall (tympanic membrane). Here it crosses medial aspect of handle of malleus and lateral aspect of long process of incus. At the anterior margin of tympanic membrane it enters anterior canaliculus in the anterior wall of the middle ear and passes via canaliculus and emerges at the base of skull through medial end of petrotympanic fissure. It then goes medially, forwards and downwards, grooves the medial side of the spine of the sphenoid, running anteroinferiorly deep to lateral pterygoid to join the posterior aspect of the lingual nerve about 2 cm below the base of the skull.
 
Distribution
  • Chorda tympani nerve supplies secretomotor fibers to submandibular and sublingual gland via submandibular ganglion.
  • It carries taste sensations from anterior 2/3rd of tongue.
zoom view
Fig. 29: Origin, course and relations of chorda tympani nerve
Q.21. Describe facial nerve under following heads:
(Oct 2014, 3+3+2 Marks)
a. Nucleus
b. Course and branches
c. Applied anatomy
Ans. For nucleus of facial nerve refer to Ans 16 of the same chapter.
For course of facial nerve refer to Ans 16 of the same chapter. For branches of facial nerve refer to Ans 7 of the same chapter.
For applied anatomy of facial nerve refer to Ans 9 of the same chapter.
Q.22. Write a short note on blood and nerve supply of face.
(Dec 2010, 5 Marks)
Ans. For blood supply of face refer to Ans 3 of the same chapter.
For nerve supply refer to Ans 1 of the same chapter.
Q.23. Describe facial nerve under following heads:
(Apr 2015, 3+3+2 Marks)
a. Intracranial course
b. Extracranial course and branches
c. Applied anatomy
Ans. Intracranial Course of Facial Nerve
Facial nerve is attached to the brainstem by two roots, i.e. motor and sensory. Two roots of facial nerve are attached to lateral part of lower border of pons which is just medial to eighth cranial nerve. Two roots run laterally and forward with eighth nerve to reach internal acoustic meatus.
zoom view
Fig. 30: Horizontal disposition of deep cervical fascia
In the meatus motor root lies in a groove on eighth nerve with sensory root intervening. At fundus of meatus two roots, i.e. sensory and motor fuse to form a single trunk which lie in the petrous temporal bone. In the canal course of nerve is divided into three parts by two bends. First part get directed laterally above vestibule, second part go backwards in relation to medial wall of middle ear above promontory. Third part move vertically downwards behind promontory. First bend is at the junction of first and second part is sharp. This bend lies above the anterosuperior part of promontory and is known as genu. Second bend is gradual and lie between promontory and aditus to mastoid antrum. Facial nerve leaves the skull by passing stylomastoid foramen.
For extracranial course of nerve and branches refer to Ans 7 of the same chapter.
For applied anatomy of facial nerve refer to Ans 9 of the same chapter.
Q.24. Write a short note on retromandibular vein.
(Sep 2017, 2 Marks)
Ans. Superficial temporal vein descends in front of tragus and enters the parotid gland. Here it joins the maxillary vein and form retromandibular vein.
Retromandibular vein on leaving parotid gland is divided into two divisions, i.e. anterior and posterior.
  1. Anterior division joins facial vein to form common facial vein which drains to internal jugular vein.
  2. Posterior division joins posterior auricular vein to form external jugular vein which drains to subclavian vein.21
zoom view
Fig. 31: Retromandibular vein
Q.25. Describe muscle of facial expression.
(Aug 2018, 10 Marks)
Ans. Following are the muscles of facial expression:
Name
Origin
Insertion
Actions
Muscles of eyelid
Corrugator supercilii
From medial end of superciliary arch
Into the skin of mid eyebrow
It produces vertical lines on forehead
Orbicularis oculi
  • Orbital part, on and around the orbital margin
  • Palpebral part, in the lids
  • Lacrimal part, lateral and deep to lacrimal sac
  • From medial part of medial palpebral ligament, frontal process of maxilla and nasal part of frontal bone
  • From lateral part of medial palpebral ligament
  • From lacrimal fascia and posterior lacrimal crest, forms sheath for lacrimal sac
  • Into the concentric rings return to the point of origin
  • Into lateral palpebral raphe
  • It pass laterally in front of tarsal plates of eyelids to the lateral palpebral raphe
  • It protects eye from bright light, wind and rain by forcefully closure of eyelids.
  • It closes eyelids gently as in blinking and sleeping.
  • It dilates lacrimal sac for sucking of lacrimal fluid into the sac, directs lacrimal puncta into lacus lacrimalis. It also supports the lower lid
Muscles around nasal opening
Procerus
From nasal bone and upper part of lateral nasal cartilage
Into skin of forehead between eyebrows and over the bridge of the nose bridge of the nose
It leads to transverse wrinkles
Compressor naris
From maxilla just lateral to nose
Into aponeurosis across the dorsum of nose
It leads to compression of nasal aperture
Dilator naris
From maxilla over the lateral incisor tooth
Into the alar cartilage of nose
It leads to dilation of nasal aperture
Depressor septi
From axilla over the medial incisor
Into the lower mobile part of nasal septum
It pull the nose inferiorly
Muscles around the lips
Orbicularis oris
  • Intrinsic part, deep stratum, very thin sheet
  • Extrinsic part, two strata, formed by converging muscles
  • Superior incisivus is derived from maxilla and inferior incisivus, is derived from mandible
  • Thickest middle stratum is derived from buccinator; thick superficial stratum is derived from elevators and depressors of lips and their angles
  • Into the angle of mouth
  • Into the lips and angle of mouth
It closes lips as well as protrudes lips, numerous extrinsic muscles make it most versatile for various types of grimaces22
Buccinator
It is the muscle of the cheek
  • Upper fibers are derived from maxilla opposite molar teeth
  • Lower fibers are derived from mandible, opposite molar teeth
  • Middle fibers are derived from pterygomandibular raphe
  • Upper fibers straight into the upper lip
  • Lower fibers straight into the lower lip
  • Middle fibers decussate
It flattens the cheek against gums and teeth. It also prevents accumulation of food into the vestibule
Levator labii superioris alaeque nasi
From frontal process of maxilla
Into the upper lip and alar cartilage of nose
It lifts upper lip and dilates the nostril
Zygomaticus major
From posterior aspect of lateral surface of zygomatic bone
Into the skin at the angle of mouth
It pulls the angle upwards and laterally as in smiling
Levator labii superioris
From infraorbital margin of maxilla
Into the skin of upper lateral half of upper lip
It elevates the upper lip, forms nasolabial groove
Levator anguli oris
From maxilla just below infraorbital foramen
Into the skin of angle of mouth
It elevates angle of mouth and forms nasolabial groove
Zygomaticus minor
From anterior aspect of lateral surface of the zygomatic bone
Into the upper lip medial to its angle
It leads to elevation of the upper lip
Depressor anguli oris
From oblique line of mandible below first molar, premolar and canine teeth
Into the skin at angle of mouth and fuses with orbicularis oris
It draws angle of mouth both downwards and laterally
Depressor labii inferioris
From anterior part of anterior line of mandible
Into the lower lip at midline, fuses with muscles from the opposite side
It draws lower lip downwards
Mentalis
From mandible inferior to incisor teeth
Into the skin of chin
It both elevates and protrudes lower lip as it wrinkles skin on the chin
Risorius
From fascia on to the massater muscle
Into the skin at angle of mouth
It retracts the angle of mouth
Muscles of the neck
Platysma
  • From upper part of pectoral and deltoid fasciae.
  • Its fibers run upward and mesially
  • Anterior fibers into the base of mandible
  • Posterior fibers into the skin of lower face and lip and can be continuous with risorius
  • It releases pressure of skin on subjacent veins
  • It depresses mandible
  • It pulls the angle of mouth downwards during frightening
zoom view
Fig. 32: Muscles of facial expression
 
234. SIDE OF THE NECK
Q.1. Write short answer on investing layer of neck.
(Apr 2018, 3 Marks)
Ans. The investing layer of deep cervical fascia lies deep to platysma, and surround neck like a collar. It forms the roof of posterior triangle of neck.
 
Attachments
  1. Superiorly
    1. External occipital protuberance
    2. Superior nucal line
    3. Mastoid process
    4. Base of mandible
    5. Between the angle of mandible and mastoid process, the fascia splits to enclose parotid gland. The superficial lamina is thick and dense and is attached to zygomatic arch. The deep lamina is thin and is attached to styloid process, mandible and tympanic plate. Between styloid process and angle of mandible deep lamina is thick and forms stylomandibular ligament which seperates parotid gland from submandibular gland and is pierced by the external carotid artery. At base of mandible it encloses submandibular gland superficial lamina is attached to the lower border of body of mandible and deep lamina to mylohyoid line.
  2. Inferiorly
    1. Spine of scapula
    2. Clavicle
    3. Acromion process
    4. Manubrium
    Fascia splits to enclose suprasternal and supraclavicular spaces.
    zoom view
    Fig. 33: Horizontal disposition of deep cervical fascia
  3. Posteriorly
    1. Ligamentum nuchae
    2. Spine of seventh cervical vertebrae
  4. Anteriorly
    1. Symphysis menti
    2. Hyoid bone
    Both above and below hyoid bone, it is continuous with fascia of opposite side.
 
Other Features
  1. The investing layer of deep cervical fascia splits to enclose trapezius, sternomastoid, parotid, submandibular gland and suprasternal and supraclavicular space.
  2. It also forms pulleys to bind tendons of digastric and omohyoid muscles.
    zoom view
    Fig. 34: Vertical disposition of deep cervical fascia
  3. 24It forms roof of anterior and posterior triangles.
  4. It forms stylomandibular ligament and parotidomasseteric fasciae.
Q.2. Describe the carotid sheath.
(Sep 2001, 6 Marks)
Or
Answer in brief contents of carotid sheath.
(Feb 2016, 2 Marks)
Or
Write a short note on carotid sheath.
(Sep 2017, 3 Marks) (Oct 2016, 3 Marks)
Or
Name the contents of carotid sheath.
(Aug 2018, 1 Mark)
Ans. It is the condensation of the fibroareolar tissue around main vessels of neck and vagus nerve.
zoom view
Fig. 35: Carotid sheath
 
Extent
It extends from base of skull above to the arch of aorta below.
 
Contents
  1. Internal jugular vein
  2. Common carotid artery
  3. Internal carotid artery
  4. Vagus nerve.
 
Relations
  1. The ansa cervicalis lie embeded in anterior wall of carotid sheath.
  2. The cervical sympathetic chain lie behind the sheath, plastered to prevertebral fascia.
  3. The sheath is overlapped by anterior border of sternomastoid, and is fused to all three layers of deep cervical fascia.
Q.3. Mention boundaries and contents of posterior triangle of neck.
(Feb 2002, 10 Marks) (Sep 2001, 12 Marks)
Or
Write a short note on contents of posterior triangle of neck.
(Apr 2010, 5 Marks)
Or
Describe boundaries and contents of posterior triangle of neck
(Aug 2012, 10 Marks)
Or
Write short note on boundaries of posterior triangle of neck
(Sep 2013, 5 Marks)
Or
Write short note on boundaries and content of posterior triangle of neck
(Oct 2016, 3 Marks)
Or
Draw a well labeled diagram showing boundaries and contents of posterior triangle of neck. [No description is required]
(Dec 2012, 4 Marks)
Ans. Boundaries of Posterior Triangle
  • Anterior: Formed by posterior border of sterno-mastoid.
  • Posterior: Formed by anterior border of trapezius.
  • Inferior or base: Formed by middle 1/3 of clavicle.
  • Apex: Lies on superior nucal line where the trapezius and sternocleidomastoid meet.
  • Roof: Roof is formed by the investing layer of deep cervical fascia.
  • Floor: Floor of posterior triangle is formed by prevertebral layer of deep cervical fascia covering the following muscles:
    1. Splenius capitis
    2. Levator scapulae
    3. Scalenus medius
    4. Semispinalis capitis may also form part of floor.
 
Contents of Posterior Triangle
Contents
Occipital triangle
Subclavian triangle
A. Nerves
  1. Spinal accessory nerve
  2. Four cutaneous branches of cervical plexus
    1. Lesser occipital
    2. Greater auricular
    3. Anterior cutaneous nerve of neck
    4. Supraclavicular nerve
  3. Muscular branches
    1. Two small branches to levator scapulae
    2. Two small branches to trapezius
    3. Nerve to rhomboids
  4. C5, C6 roots of brachial plexus
  1. Three trunks of brachial plexus
  2. Nerve to serratus anterior
  3. Nerve to subclavius
  4. Suprascapular nerve
25
B. Vessels
  1. Transverse cervical artery and vein
  2. Occipital artery
  1. Third part of subclavian artery and vein
  2. Suprascapular artery and vein
  3. Commencement of transverse cervical artery and termination of corresponding vein
  4. Lower part of external jugular vein
C. Lymph nodes
Supraclavicular and occipital lymph nodes
Few members of supraclavicular chain
zoom view
Fig. 36: Boundaries of posterior triangle
zoom view
Fig. 37: Contents of posterior triangle
zoom view
Fig. 38: Muscles forming floor of posterior triangle
Q.4. Write a short note on sternocleidomastoid muscle.
(Sep 2004, 10 Marks) (Feb 1999, 4 Marks)(Apr 2007, 5 Marks) (Aug 2011, 5 Marks)
(Aug 2016, 3 Marks)
Or
Write short note on sternomastoid muscle.
(May/June 2009, 5 Marks)
Ans. Introduction: It is a largest muscle of side of neck and divides it into two triangles, i.e. anterior triangle and posterior triangle.
Origin: It takes origin from two heads.
  1. Sternal head: It takes origin from superolateral part in front of manubrium sterni.
  2. Clavicular head: It takes origin from medial 1/3 of superior aspect of clavicle. It passes vertically upward deep to sternal head with which it unites to form a fusion belly.
Insertion: Muscle is inserted:
  1. By a thick tendon into the lateral surface of mastoid process from its tip to superior border.
  2. By thin aponeurosis into the lateral half of superior nuchal line of occipital bone.
Nerve supply
  • Spinal accessory nerve provides motor supply.
  • Branches from ventral rami of C2 are proprioceptive.
 
Relations
The sternocleidomastoid muscle is enclosed in the investing layer of deep cervical fascia, and is pierced by the accessory nerve and by the four sternocleidomastoid arteries. It has the following relations.
Superficial Relations
  • Skin
  • Superficial fascia
    • Superficial lamina of the deep cervical fascia
  • Platysma.
  • 26External jugular vein and superficial cervical lymph nodes lying along the vein.
  • Great auricular
    • Transverse or anterior cutaneous.
    • Medial supraclavicular nerves
    • Lesser occipital nerve
  • The parotid gland overlaps the muscle.
Deep Relations
  • Bones and joints:
    • Mastoid process above
    • Sternoclavicular joint below.
  • Carotid sheath
  • Muscles:
    • Sternohyoid
    • Sternothyroid
    • Omohyoid
    • Three scaleni
    • Levator scapulae
    • Splenius capitis
    • Longissimus capitis
    • Posterior belly of digastric.
  • Arteries:
    • Common carotid
    • Internal carotid
    • External carotid
    • Sternocleidomastoid arteries, two from the occipital artery, one from the superior thyroid, one from the suprascapular
    • Occipital
    • Subclavian
    • Suprascapular
    • Transverse cervical
  • Veins:
    • Internal jugular
    • Anterior jugular
    • Facial
    • Lingual
  • Nerves:
    • Vagus
    • Parts of IX, XI, XII
    • Cervical plexus
    • Upper part of brachial plexus
    • Phrenic
    • Ansa cervicalis
  • Lymph nodes, deep cervical.
 
Blood Supply
Arterial supply is from one branch, i.e. each from superior thyroid artery and suprascapular artery and two branches from the occipital artery supply the big muscle. Veins follow the arteries.
Actions
  • When one muscle contracts:
    • It turns the chin to the opposite side.
    • It can also tilt the head towards the shoulder of same side.
  • When both muscles contract together:
    • They draw the head forwards, as in eating and in lifting the head from a pillow.
    • With the longus colli, they flex the neck against resistance.
    • It also helps in forced inspiration.
 
Applied Anatomy
  • Torticollis or wry neck: It is a clinical condition in which head is bent to one side and chin points to opposite side. This occur because of spasm of sternocleidomastoid and trapezius muscles.
  • Sternomastoid tumor: It is the swelling in middle third of sternomastoid muscle due to edema and ischemic necrosis caused by the birth trauma.
zoom view
Fig. 39: Sternocleidomastoid muscle
Q.5. Write a short note on external jugular vein.
(Oct 2016, 3 Marks) (Apr 2008, 5 Marks)
(Oct 2007, 5 Marks) (Mar 2009, 5 Marks)
Ans. It is a large vein present in superficial fascia under cover of platysma muscle.
zoom view
Fig. 40: The external jugular vein
 
27Course
  • External jugular vein is formed by the union of posterior division of retromandibular vein and posterior auricular vein behind mandible just below parotid gland.
  • The origin lies within the lower part of parotid gland or just below it. The level corresponds to angle of mandible. From here vein run downwards and somewhat backwards and ends by joining subcutaneous vein.
  • The termination lies behind middle of the clavicle, near lateral margin of scalene anterior muscle.
  • The greater part of vein is superficial being covered by skin, superficial fascia and platysma. It pierces the deep fascia near its termination to reach subcutaneous vein.
  • The vein crosses the sternocleidomastoid obliquely running downwards and backwards at the level of anteroinferior angle of posterior triangle. It pierces the deep fascia and opens in subclavian vein.
 
Tributaries
  1. Transverse cervical vein
  2. Suprascapular vein
  3. Anterior jugular vein
  4. Posterior external jugular vein.
Oblique jugular vein connects external jugular vein with internal jugular vein across middle one-third of anterior border of sternocleidomastoid.
 
Applied Anatomy
  • Right external jugular vein is examined to assess the venous pressure; right atrial pressure is reflected in it as there are no valves in it through its entire course. It is straight.
  • As external jugular vein pierces the fascia, margins of vein adhere to fascia. So if vein get cut, it should not be closed and air is sucked due to negative intrathoracic pressure. This leads to air embolism for preventing this deep fascia has to be cut.
Q.6. Discuss anatomy of posterior triangles of neck. Add a note on its applied anatomy.
(June 2010, 10 Marks)
Ans. Posterior triangle is subdivided by inferior belly of omohyoid into:
  1. A large upper part which is known as occipital triangle.
  2. A smaller lower part which is known as supraclavicular or subclavian triangle.
 
Occipital Triangle
From above to downward it consists of:
  • Occipital artery at apex
  • Spinal accessory nerve
  • Four cutaneous branches of cervical plexus, i.e.
    1. Lesser occipital
    2. Greater auricular
    3. Anterior cutaneous nerve of neck
    4. Supraclavicular nerves.
  • Transverse cervical artery and vein
  • Muscular branches:
    1. Two small branches to levator scapulae
    2. Two small branches to trapezius
    3. Nerve to rhomboids.
  • C5 and C6 roots of brachial plexus.
Occipital artery: It crosses the apex of posterior triangle superficial to splenius capitis
Spinal accessory nerve: It emerges little above the middle of posterior border of sternocleidomastoid. It runs via tunnel in the fascia and form roof of triangle and pass downward and laterally and disappear under anterior border of trapezius.
Four cutaneous branches of cervical plexus: All the branches pierce fascia covering floor of triangle and pass through the triangle and pierce the deep fascia to become cutaneous.
  1. Anterior cutaneous nerve: Arises from ventral rami of C2 and C3 and run across sternomastoid to supply skin and neck to sternum.
  2. Supraclavicular nerve: Formed by ventral rami of C3 and C4 nerves. The nerve emerges at posterior border of sternocleidomatoid muscle.
  3. Greater auricular nerve: It is the largest ascending branch of cervical plexus. It arises from ventral rami of C2 and C3 nerves. It ascends on sternomastoid muscle to reach parotid gland where it subdivides into anterior and posterior branches.
  4. Lesser occipital: It arises from ventral ramus of C2 of spinal cord. It is visible at posterior border of sternocleidomastoid muscle.
  • Transverse cervical artery: It is a branch of thyrocervical trunk. It crosses scalenus anterior, phrenic nerve, upper trunk of brachial plexus, nerve to subclavius, supra-scapular nerve and scalenus medius.
  • Muscular branches: These branches appear about middle of sternocleidomastoid. Those to levator scapulae ends into it and branches to trapezius runs below and parallel to accessory nerve across the middle of the triangle.
 
Subclavian Triangle
It consists of:
  • Three trunks of brachial plexus.
  • Nerve to serratus anterior.
  • Nerve to subclavius.
  • Suprascapular nerve.
  • Subclavian artery.
  • Suprascapular artery.
  • Subclavian vein.
Three trunks of brachial plexus: They emerge between scalenus anterior and scalenus medius. It carries axillary sheath around them. Sheath consists of brachial plexus and subclavian artery. All the structures lie deep to the floor of triangle.
Nerve to serratus anterior: It arises by three roots. Roots from C5 and C6 pierce the scalenus medius and join the root from C7 over the first digitations of serratus anterior.
28Nerve to subclavius: It descends in front of brachial plexus and subclavian vessels but behind omohyoid, transverse cervical and suprascapular vessels and the clavicle to reach deep surface of subclavius muscle.
Suprascapular nerve: It arises from the upper trunk of brachial plexus and crosses the lower part of posterior triangle just above and lateral to brachial plexus, deep to transverse cervical vessels and omohyoid muscle.
Subclavian artery: It passes behind the tendon of scalenus anterior over the first rib.
Suprascapular artery: It is the branch of thyrocervical trunk and passes laterally and backward behind clavicle.
Subclavian vein: It passes in front of tendon of scalenus anterior muscle.
For diagrams of this answer refer to Ans 3 of the same chapter.
 
Applied Anatomy
  • Most common swelling in the posterior triangle occurs because of enlargement of the supraclavicular lymph nodes. At the time of biopsy of lymph node, surgeon must be careful in preserving the accessory nerve which may get entangled amongst enlarged lymph nodes.
  • Supraclavicular lymph nodes are commonly enlarged in tuberculosis, Hodgkin's disease, and in malignant growths of the breast, arm or chest.
  • Block dissection of the neck for malignant diseases is the removal of cervical lymph nodes along with other structures involved in the growth. This procedure does not endanger those nerves of the posterior triangle which lie deep to the prevertebral fascia, i.e. the brachial and cervical plexuses and their muscular branches.
  • A cervical rib may compress the second part of subclavian artery. In these cases, blood supply to upper limb reaches via anastomoses around the scapula.
  • Dysphagia caused by compression of the esophagus by an abnormal subclavian artery is called dysphagia lusoria.
Q.7. Briefly describe posterior triangle of neck.
(Apr 2007, 15 Marks)
Ans. For boundaries and contents of posterior triangle of neck refer to Ans 3 of the same chapter.
For various posterior triangles of neck with their applied anatomy refer to Ans 6 of the same chapter.
Q.8. Answer in brief muscles forming the floor of posterior triangle of neck.
(Oct 2016, 2 Marks)
Ans. Muscles forming the floor of posterior triangle of neck are:
  • Splenius capitis
  • Levator scapulae
  • Scalenus medius
  • Semispinalis capitis
Muscular floor of posterior triangle is covered by the prevertebral layer of deep cervical fascia which forms first carpet of floor of posterior triangle of neck.
zoom view
Fig. 41: Floor of posterior triangle of neck
Q.9. Write in short on deep fascia of neck.
(Aug 2012, 5 Marks)
Ans. Deep fascia of neck is condensed to form following layers, i.e.
  • Investing layer
  • Pretracheal layer
  • Prevertebral layer
  • Carotid sheath
  • Buccopharyngeal fascia
  • Pharyngobasilar fascia
 
Investing Layer
This layer lies deep to platysma and surrounds neck like a collar. It forms roof of posterior triangle of neck.
For more details refer to Ans 1 of the same chapter.
 
Pretracheal Layer
Importance of this fascia is that it encloses and suspends the thyroid gland and forms its false capsule.
 
Prevertebral Fascia
It lies in front of prevertebral muscles and forms the floor of posterior triangle of neck.
 
Carotid Sheath
It is a condensation of fibroareolar tissue around the main vessels of neck. It is formed on anterior aspect by the pretracheal fascia and on posterior aspect by prevertebral fascia. Contents are common or internal carotid arteries, internal jugular vein 29and vagus nerve. Carotid sheath is thin over the vein. In upper part of sheath there are IX, XI, XII nerves also. These nerves pierce along with external carotid artery.
 
Buccopharyngeal Fascia
It covers the superior constrictor muscle externally and extends on superficial aspect of buccinator muscle.
 
Pharyngobasilar Fascia
This layer is specially thickened between upper border of superior constrictor muscle and base of skull. This layer lies deep to pharyngeal muscles.
Q.10. Define torticollis.
(Aug 2018, 1 Mark)
Ans. It is a clinical condition in which head is bent to one side and chin points to opposite side.
 
5. ANTERIOR TRIANGLE OF NECK
Q.1. Write a short note on boundaries and contents of carotid triangle.
(Sep 2004, 5 Marks)
Or
Write short answer on contents of carotid triangle.
(Aug 2018, 3 Marks)
Ans. Boundaries of Carotid Triangle
  • Anterosuperiorly: Posterior belly of digastric muscle and stylohyoid
  • Anteroinferiorly: Superior belly of omohyoid.
  • Posteriorly: Anterior border of sternocleidomastoid muscle.
Roof:
  1. Skin.
  2. Superfacial fascia containing:
    1. Platysma.
    2. Cervical branch of facial nerve.
    3. Transverse cutaneous nerve of neck.
  3. Investing layer of deep cervical fascia
Floor: It is formed by part of:
  1. Middle constrictor of pharynx
  2. Inferior constrictor of pharynx
  3. Thyrohyoid membrane.
 
Contents of Carotid Triangle
  1. Arteries:
    • Common carotid artery with carotid sinus and carotid body at its termination
    • Internal carotid artery
    • External carotid artery with its superior thyroid, lingual, facial, ascending pharyngeal and occipital branches.
  2. Veins:
    • Internal jugular vein
    • Common facial vein draining into internal jugular vein.
    • Pharyngeal vein which end in internal jugular vein.
    • Lingual vein which terminates in internal jugular vein.
    zoom view
    Fig. 42: Boundaries and contents of carotid triangle
  3. Nerves:
    • Vagus running vertically downwards
    • Superior laryngeal branch of vagus, dividing in external and internal laryngeal nerves.
    • Spinal accessory nerve running backward over internal jugular vein
    • Hypoglossal nerve running forward over external and internal carotid artieries
    • Sympathetic chain run vertically downward posterior to carotid sheath. Carotid sheath with its contents.
  4. Lymph nodes: Deep cervical lymph nodes are situated along internal jugular vein, and include jugulodiagastric node below the posterior belly of digastric and jugulo-omohyoid node above the inferior belly of omohyoid.
Q.2. Write a short note on ansa cervicalis (Ansa Hypoglossi).
(Sep 2004, 5 Marks) (Dec 2010, 3 Marks)(Feb 2014, 3 Marks)
Or
Write short note on ansa cervicalis.
(Sep 2018, 5 Marks)
(Aug 2016, 3 Marks) (Nov 2008, 5 Marks)
Or
Write short answer on ansa cervicalis.
(Aug 2018, 3 Marks)
Ans. It is a thin nerve loop that lies embedded in the anterior wall of carotid sheath on lower part of larynx. It supplies infrahyoid muscles.
30Formation: It is formed by superior and inferior root.
  • Superior root is continuation of descending branch of hypoglossal nerve. Its fibers are derived from first cervical nerve. This root descends over internal carotid artery and common carotid artery.
  • Inferior root is derived from second and third cervical spinal nerves. As this root descends, it winds round the internal jugular vein and then continues anterioinferiorly to join superior root in front of common carotid artery.
 
Distribution
  • Superior root: To the superior belly of omohyoid.
  • Ansa Cervicalis: To sternohyoid, sternothyroid and inferior belly of omohyoid.
 
Diagram of Ansa Cervicalis
zoom view
Fig. 43: Ansa cervicalis
Q.3. Enumerate the branches of external carotid artery.
(Mar 2000, 4 Marks) (Apr 2007, 3 Marks)(Sep 2007, 3 Marks) (Feb 2013, 2 Marks)
Or
Name the branches of external carotid artery.
(Aug 2018, 1 Mark)
Ans. It gives off 8 branches which are:
  1. Anteriorly
    1. Superior thyroid artery.
    2. Lingual artery.
    3. Facial artery.
  2. Posteriorly
    1. Occipital artery.
    2. Posterior auricular artery.
  3. Medially
    1. Ascending pharyngeal artery.
  4. Terminally
    1. Maxillary artery.
    2. Superficial temporal artery.
zoom view
Fig. 44: Branches of external carotid artery
Q.4. Write a short note on lingual artery.
(Aug/Sep 1998, 4 Marks)
Ans. The lingual artery arises from the external carotid artery opposite the tip of the greater cornua of the hyoid bone. This artery is tortuous in its course. Its course is divided into three parts by the hyoglossus muscle:
  1. First part lies in the carotid triangle. It forms a characteristic upward loop which is crossed by the hypoglossal nerve. The lingual loop permits free movements of the hyoid bone.
  2. Second part lies deep to the hyoglossus along the upper border of hyoid bone. It is superficial to the middle constrictor of the pharynx.
  3. Third part is called the arteria profunda linguae, or the deep lingual artery. It runs upwards along the anterior border of the hyoglossus, and then horizontally forwards on the undersurface of the tongue as the fourth part.
In its vertical course, it lies between the genioglossus medially and the inferior longitudinal muscle of the tongue laterally. The horizontal part of the artery is accompanied by the lingual nerve.
During surgical removal of tongue the first part of artery is ligated before it gives any branch to tongue or to the tonsil.
zoom view
Fig. 45: Lingual artery
31Q.5. Write short note on digastric triangle.
(Feb 2013, 5 Marks) (May/June 2009, 5 Marks)
(Aug 2016, 3 Marks)
Ans. Digastric triangle is so named because it is located between the two bellies of digastric muscle and below the base of mandible.
The boundaries of the digastric triangle are as follows:
  • Anteroinferiorly: Anterior belly of digastric.
  • Posteroinferiorly: Posterior belly of digastric and stylohyoid.
  • Superiorly (base): Base of the mandible and a line joining the angle of the mandible to the mastoid process.
  • Roof: The roof of the triangle is formed by:
    1. Skin.
    2. Superficial fascia containing:
      1. Platysma
      2. Cervical branch of the facial nerve
      3. The ascending branch of the transverse (anterior) cutaneous nerve of the neck.
    3. Deep fascia, which splits to enclose the submandibular salivary gland.
  • Floor: The floor is formed by the mylohoid muscle anteriorly, and by the hyoglossus posteriorly. A small part of the middle constrictor muscle of the pharynx appears in the floor.
zoom view
Fig. 46: Boundaries of digastric triangle
 
Contents
  1. Anterior part of the triangle
    1. Structures superficial to mylohyoid are:
      1. Superficial part of the submandibular salivary gland.
      2. The facial vein and submandibular lymph nodes are superficial to it and the facial artery is deep to it.
      3. Submental artery.
      4. Mylohyoid nerve and vessels.
    2. Structures superficial to the hyoglossus are:
      1. Submandibular salivary gland
      2. Intermediate tendon of the digastric and the stylohyoid
      3. Hypoglossal nerve.
  2. Posterior part of the triangle
    1. Superficial structures are:
      1. Lower part of the parotid gland
      2. External carotid artery before it enters the parotid gland.
    2. Deep structures passing between the external and internal carotid arteries are:
      1. Styloglossus
      2. Stylopharyngeus
      3. Glossopharyngeal nerve
      4. Pharyngeal branch of the vagus nerve
      5. Styloid process
      6. Part of the parotid gland.
    3. Deepest structures include:
      1. Internal carotid artery
      2. Internal jugular vein
      3. Vagus nerve.
Q.6. Write short note on branches of external carotid artery.
(Jun 2010, 5 Marks)
Or
Write about branches of external carotid artery.
(Sep 2013, 5 Marks)
Ans. External carotid artery is the terminal branch of common carotid artery.
External carotid artery gives off 8 branches:
 
Anterior Branches
  • Superior thyroid artery: It passes deep to three long infrahyoid muscles to reach the upper pole of lateral lobe of thyroid gland. Apart from its terminal branches to thyroid gland, it gives one important branch, i.e. superior laryngeal artery which pierces thyrohyoid membrane in company with internal laryngeal nerve.
  • Lingual artery: The lingual artery arises from the external carotid artery opposite the tip of the greater cornua of the hyoid bone. This artery is tortuous in its course. Its course is divided into three parts by the hyoglossus muscle:
    • First part lies in the carotid triangle. It forms a characteristic upward loop which is crossed by the hypoglossal nerve. The lingual loop permits free movements of the hyoid bone.
    • Second part lies deep to the hyoglossus along the upper border of hyoid bone. It is superficial to the middle constrictor of the pharynx.
    • Third part is called the arteria profunda linguae, or the deep lingual artery. It runs upwards along the anterior border of the hyoglossus, and then horizontally forwards on the undersurface of the tongue as the fourth part.
    • In its vertical course, it lies between the genioglossus medially and the inferior longitudinal muscle of the tongue laterally. The horizontal part of the artery is accompanied by the lingual nerve.
  • Facial artery: It arises from the external carotid just above the tip of the greater cornua of the hyoid bone. It runs 32upwards first in the neck as cervical part and then on the face as facial part. The course of the artery in both places is tortuous.
    • Cervical part of the facial artery runs upwards on the superior constrictor of pharynx deep to the posterior belly of the digastric with the stylohyoid and to the ramus of the mandible. It grooves the posterior border of the submandibular salivary gland. Next the artery makes an S-bend (two loops) first winding down over the submandibular gland, and then up over the base of the mandible.
    • Facial part of the facial artery enters the face at anteroinferior angle of masseter muscle, runs upwards close to angle of mouth, side of nose till medial angle of eye.
    • The cervical part of the facial artery gives off the ascending palatine, tonsillar, submental, and glandular branches for the submandibular salivary gland and lymph nodes.
    • Ascending palatine artery arises near the origin of the facial artery. It passes upwards between the styloglossus and stylopharyngeus crosses over the upper border of the superior constrictor and supplies the tonsil and the root of the tongue.
    • Submental branch is a large artery which accompanies the mylohyoid nerve, and supplies the submental triangle and the sublingual salivary gland.
 
Posterior Branches
  • Occipital artery: It arises from the posterior aspect of the external carotid artery, opposite the origin of the facial artery. Hypoglossal nerve cross this artery at its origin. In the carotid triangle the artery gives off two sternocleidomastoid branches. Upper branch accompanies accessory nerve and lower branches arises near origin of occipital artery.
  • Posterior auricular artery: It arises from posterior aspect of external carotid just above the posterior belly of diagastric. It run upward and backward deep to parotid gland and superficial to styloid process. It crosses base of mastoid process and ascend behind auricle. It supplies back of auricle skin over mastoid process and over back of scalp.
 
Medial Branches
Ascending pharyngeal: It is a small branch which arises from medial side of external carotid artery. It runs vertically upwards between the side wall of pharynx, tonsil, medial wall of middle ear and auditory tube. It send meningeal branches in cranial cavity via foramen lacerum, jugular foramen and hypoglossal canal.
 
Terminal Branches
  1. Maxillary artery: It is the larger branch and begins behind the neck of mandible. It run forward deep to the neck of mandible below auriculotemporal nerve and enter infratemporal fossa.
  2. Superficial temporal artery: Refer to Ans 7 of the same chapter.
Q.7. Write short note on superficial temporal artery.
(Sep 2013, 5 Marks)
Ans. It is the smaller branch and begins behind the neck of mandible under the cover of parotid gland.
  • It runs vertically upwards crossing the root of zygoma or preauricular point where its pulsations can be felt. It divides into anterior and posterior branches which supply to temple and scalp.
  • Anterior branch anastomose with supraorbital and supratrochlear branches of ophthalmic artery.
  • In addition to the various branches which supply temple, parotid gland, scalp, auricle and facial muscles, it gives off transverse facial artery and a middle temporal artery which run on temporal fossa deep to temporalis muscle.
Q.8. Write briefly on external carotid artery and its branches.
(Aug 2012, 5 Marks)
Or
Write in brief on external carotid artery.
(Sep 2015, 5 Marks)
Ans. External carotid artery is one of the terminal branches of the common carotid artery. It lies anterior to the internal carotid artery, and is the main artery of supply to structures in the front of neck and in the face.
 
Course and Relations
  • It begins inside the carotid triangle at the level of upper border of the thyroid cartilage opposite the disc between third and fourth cervical vertebrae. The artery runs upwards and slightly backwards and laterally, and terminates behind the neck of mandible by dividing into maxillary and superficial temporal arteries.
  • External carotid artery consists of slightly curved course, so that it is anteromedial to internal carotid artery in its lower part and anterolateral to internal carotid artery in its upper part.
  • In carotid triangle, external carotid artery is comparatively superficial, and lies under cover of anterior border of the sternocleidomastoid. It is crossed superficially by the cervical branch of facial nerve, hypoglossal nerve, and facial, lingual and superior thyroid veins. Deep to external carotid artery lies:
    • The wall of the pharynx.
    • Superior laryngeal nerve which divides into external and internal laryngeal nerves.
    • Ascending pharyngeal artery
  • Above the carotid triangle, external carotid artery lies deep in the substance of parotid gland. Within the gland, it is related superficially to the retromandibular vein and the facial nerve. Deep to external carotid artery, there are:
    • Internal carotid artery.
    • Structures passing between the external and internal carotid arteries, i.e. styloglossus, stylopharyngeus, glossopharyngeal nerve, pharyngeal branch of vagus, and styloid process.
    • Two structures deep to internal carotid artery, namely the superior laryngeal nerve and superior cervical sympathetic ganglion.33
zoom view
Fig. 47: External carotid artery with its branches
 
Branches of External Carotid Artery
It gives off 8 branches which are:
Anteriorly
  • Superior thyroid artery.
  • Lingual artery.
  • Facial artery.
Posteriorly
  • Occipital artery.
  • Posterior auricular artery.
Medially
  • Ascending pharyngeal artery.
Terminally
  • Maxillary artery.
  • Superficial temporal artery.
Q.9. Describe carotid triangle with labeled diagram.
(Apr 2018, 10 Marks)
Or
Name any four contents of carotid triangle.
(Aug 2016, 2 Marks)
Ans. Carotid triangle is so called because it consists of all three carotid arteries, i.e. common carotid, internal carotid and external carotid.
 
Boundaries of Carotid Triangle
  • Anterosuperiorly: Posterior belly of digastrics muscle; and stylohyoid
  • Anteroinferiorly: Superior belly of omohyoid.
  • Posteriorly: Anterior border of sternocleidomastoid muscle.
  • Roof:
    • Skin.
    • Superfacial fascia containing:
      • Platysma.
      • Cervical branch of facial nerve.
      • Transverse cutaneous nerve of neck.
    • Investing layer of deep cervical fascia
  • Floor: It is formed by parts of:
    • Middle constrictor of pharynx
    • Inferior constrictor of pharynx
    • Thyrohyoid membrane.
zoom view
Fig. 48: Boundaries and contents of carotid triangle
 
34Contents of Carotid Triangle
  • Arteries
    • Common carotid artery with carotid sinus and carotid body at its termination
    • Internal carotid artery
    • External carotid artery with its superior thyroid, lingual, facial, ascending pharyngeal and occipital branches.
  • Veins
    • Internal jugular vein
    • Common facial vein draining into internal jugular vein
    • Pharyngeal vein which usually ends in the internal jugular vein
    • Lingual vein which usually terminates in the internal jugular vein.
  • Nerves
    • Vagus nerve running vertically downwards
    • Superior laryngeal branch of vagus, dividing into external and internal laryngeal nerves
    • Spinal accessory nerve running backward over internal jugular vein
    • Hypoglossal nerve running forward over external and internal carotid arteries
    • Sympathetic chain running vertically downwards posterior to carotid sheath. Carotid sheath with its contents.
  • Lymph nodes: Deep cervical lymph nodes which are situated along the internal jugular vein, and include the jugulodigastric node below the posterior belly of digastrics and jugulo–omohyoid node above the inferior belly of omohyoid.
 
Relevant Features of Contents of Carotid Triangle
Common Carotid Artery
Right common carotid artery is the branch of brachiocephalic artery. It begins inside the neck behind the right sternoclavicular joint.
Left common carotid artery is the branch of arch of aorta. It begins inside the thorax in front of trachea opposite to point little to left of center of manubirum. It ascends to back of left sternoclavicular joint and enters neck.
Inside the neck both arteries have same course.
Each artery run upward inside the carotid sheath under cover of anterior border of sternocleidomastoid. At the level of upper border of thyroid cartilage, artery ends by dividing into external and internal carotid arteries.
Carotid Sinus
Termination of common carotid artery or beginning of internal carotid artery shows slight dilatation known as carotid sinus. In carotid sinus, tunica media is thin, while the tunica adventitia is thick and receives rich innervations from glossopharyngeal and sympathetic nerves. Carotid sinus act as baroreceptor and regulates blood pressure.
Carotid Body
It is a small, oval, red brown structure situated behind bifurcation of common carotid artery. It receives rich nerve supply mainly from glossopharyngeal nerve but also from vagus nerve and sympathetic nerve. Carotid body act as chemoreceptor and respond to changes occur in oxygen, carbon dioxide and pH content of blood.
External Carotid Artery and Its Branches
For details refer to Ans 8 and Ans 6 of the same chapter.
Ansa Cervicalis and Ansa Hypoglossi
For details refer to Ans 2 of same chapter.
Q.10. Name the infrahyoid muscles.
(Oct 2016, 2 Marks)
Or
Enumerate infrahyoid muscles in neck.
(Apr 2018, 2 Marks)
Ans. Infrahyoid muscles are ribbon like and comprises of following four paired muscles:
  1. Sternothyroid
  2. Sternohyoid
  3. Thyrohyoid
  4. Omohyoid
Q.11. Enumerate midline structures of neck.
(Apr 2018, 2 Marks)
Ans. Following are the midline structures of neck from above to downwards:
  • Symphysis menti
  • Fibrous raphae
  • Hyoid bone
  • Medial thyrohyoid ligament
  • Upper border of thyroid cartilage
  • Angle of thyroid cartilage
  • Median cricothyroid ligament
  • Cricoid cartilage
  • First tracheal ring
  • Isthmus of thyroid gland
  • Inferior thyroid veins
  • Thyroidea ima artery
  • Jugular venous arch
  • Suprasternal notch
 
6. THE PAROTID REGION
Q.1. Briefly describe anatomy of parotid gland and add a note on its applied anatomy.
(Sep 2009, 20 Marks)
Or
Describe gross anatomy, nerve supply and applied aspect of parotid gland.
(Jan 2012, 15 Marks)
Or
Describe briefly relations and nerve supply of parotid gland.
(Apr 2008, 5 Marks)
35Or
Describe parotid gland and its applied aspect.
(Aug 2012, 15 Marks) (Aug 2011, 15 Marks)
Or
Describe parotid gland under following headings:
a. External features
(Aug 2018, 10 Marks)
b. Relations
c. Nerve supply
d. Applied anatomy
Ans. Parotid is the largest of all salivary glands. It weights about 15 g.
Situation: It is situated below external auditory meatus, between ramus of mandible and sternomastoid. Anteriorly, the gland overlaps masseter muscle. A part of this forward extension is often detached and is known as accessory parotid, it lies between zygomatic arch and parotid duct.
 
Parotid Capsule
  • Investing layer of the deep cervical fascia forms a capsule for the gland.
  • Fascia splits to enclose the gland.
  • Superficial lamina is thick and adherent to the gland is attached above to the zygomatic arch. The deep lamina is thin and is attached to the styloid process, mandible and tympanic plate.
  • A portion of the deep lamina extending between the styloid process and mandible is thickened to form the stylomandibular ligament which separates the parotid gland from the submandibular salivary gland. External carotid artery pierces the stylomandibular ligament.
 
External Features
The gland resembles a three-sided pyramid with apex directed downwards. It presents the following features:
An apex which is directed downwards.
Four Surfaces
  1. Superior surface or base
  2. Superficial surface
  3. Anteromedial surface
  4. Posteromedial surface.
Three Borders
They seperate the surfaces:
  1. Anterior
  2. Posterior
  3. Medial.
 
Relations
  1. The apex
    It overlaps posterior belly of digastric and adjoining part of carotid triangle.
    • Cervical branch of facial nerve.
    • Two divisions of retromandibular vein.
  2. The superior surface
    It forms upper end of gland which is small and concave. It is related to:
    • Cartilaginous part of external auditory meatus.
    • Posterior surface of temporomandibular joint.
    • Superficial temporal vessels.
    • Auriculotemporal nerve.
    zoom view
    Fig. 49: Relations of parotid gland
  3. 36The superficial surface: It is the largest of all four surfaces and is covered with:
    • Skin
    • Superfacial facia containing anterior branches of great auricular nerve, preauricular lymph node and posterior fibers of platysma and risorius.
    • Parotid fascia is thick and adherent to gland
    • Few deep parotid lymph nodes embedded in gland.
  4. Anteromedial surface: It is grooved by posterior border of ramus of mandible. It is related to:
    • Masseter
    • Lateral surface of temporomandibular joint
    • Medial pterygoid
    • Posterior border of ramus of mandible
    • Emerging branches of facial nerve.
    zoom view
    Fig. 50: Shape, surfaces and borders of right parotid gland
  5. Posteromedial surface
    It is moulded to mastoid and styloid process and structures attached to them. So it is related to:
    • Mastoid process with sternocleidomastoid muscle and posterior belly of digastric
    • Styloid process with structures attached to it
    • External carotid artery enters the gland through this surface and internal carotid artery lies deep to styloid process.
  6. Anterior border
    It separates superficial surface from anteromedial surface. It is related to:
    • Parotid duct
    • Terminal branches of facial nerve
    • Transverse facial vessels.
    In addition the accessory parotid gland lies on parotid duct close to this border.
  7. Posterior border: It separates superficial surface from posteromedial surface. It overlaps sternomastoid muscle.
  8. Medial border: It separates anteromedial surface from posteromedial surface it is related to lateral wall of phaynx.
 
Structures within Parotid Gland
  1. Arteries: External carotid artery enters gland through posteromedial surface. Maxillary artery leaves gland through anteromedial surface. Superficial temporal artery give transverse facial artery and emerges at anterior part of superior surface.
    zoom view
    Fig. 51: Arterial supply
  2. Veins: Retromandibular vein is formed inside the gland by the union of superficial temporal and maxillary veins. In the lower part of gland, veins divide in anterior and posterior division which emerge at close to apex of gland.
    zoom view
    Fig. 52: Venous drainage
  3. Nerve: Facial nerve exit from cranial cavity via stylomastoid foramen and enter the gland through upper part of its posteromedial surface and divides into terminal branches inside the gland. Branches leave the gland via anteromedial surface and appear on surface of anterior border. Facial nerve lies in relation to isthumus of gland which separates large superficial part from small deep part of gland. Facial nerve divides into two branches, i.e. temporofacial and cervicofacial. Temporofacial divides into temporal and zygomatic branches, while cervicofacial divides into buccal, marginal mandibular and cervical branches.
  4. Parotid lymph nodes
    • Parotid duct: It is thick walled and is about 5 cm long. It emerges from middle of anterior border of the gland. It runs forward and slightly downward on masseter. Because of oblique course of duct through buccinator inflation of duct is prevented during blowing. The duct run forwards for a short distance between the buccinator and oral mucosa. Finally the duct turn medially and opens in vestibule of mouth opposite the crown of upper second molar tooth.37
      zoom view
      Fig. 53: Nerve supply to parotid gland
    • Blood supply:
      • Parotid gland is supplied by the external carotid artery and its branches which arise inside the gland.
      • Veins drain into external jugular vein and internal jugular vein.
 
Lymphatic Drainage
Lymph drains first to the parotid lymph nodes and from there to upper deep cervical nodes.
 
Nerve Supply
Motor Supply
  1. Parasympathetic nerves are secretomotor. They reach the gland through the auriculotemporal nerve. The preganglionic fibers begin in the inferior salivary nucleus pass through the 9th nerve, its tympanic branch, tympanic plexus and lesser petrosal nerve, and relay in otic ganglion. The postganglionic fibers pass through auriculotemporal nerve and reach the gland.
  2. Sympathetic nerves are vasomotor and they are derived from plexus at middle meningeal artery.
Sensory Supply
Sensory nerves to gland come from the auriculotemporal nerve.
Parotid fascia is innervated by the sensory fibers of greater auricular nerve.
 
Applied Anatomy
  • Parotid swellings are very painful due to unyeilding nature of parotid fascia.
  • Mumps is an infectious disease of salivary glands caused by the specific virus. Viral parotitis or mumps characteristically does not suppurate. It leads to complications such as orchitis and pancreatitis.
  • Parotid abscess is caused by spread of infection through oral cavity. An abscess may also form due to suppuration of parotid lymph nodes draining an infected area. Parotid abscess is best drained by horizontal incison called as Hilton's method.
  • During surgical removal of parotid gland, the facial nerve is preserved by removing gland into two parts, i.e. superficial and deep parts separately, plane of cleavage is defined by tracing nerve from behind forwards.
  • Mixed parotid tumor is slowly growing, lobulated, painless tumor without involvement of facial nerve. Malignant changes of such tumor are indicated by pain, rapid growth, fixity with hardness, involvement of facial nerve, enlargement of cervical lymph nodes.
Q.2. Describe the parotid gland. Write a note on its secretomotor fibers.
(Feb 2002, 10 Marks)
Ans. The parotid gland is described in Ans 1 of the same chapter.
Secretomotor fibers of parotid gland: Parasympathetic nerves are secretomotor. They reach the gland through the auriculotemporal nerve. The preganglionic fibers begin in 38the inferior salivary nucleus pass through the 9th nerve, its tympanic branch, tympanic plexus and lesser petrosal nerve, and relay in otic ganglion. The postganglionic fibers pass through the auriculotemporal nerve and reach the gland.
Q.3. Write a short note on parotid duct.
(Mar 2000, 5 Marks) (Oct 2007, 5 Marks)(Dec 2012, 3 Marks)
Ans. Introduction: It is thick walled and is about 5 cm long. It emerges from middle of anterior border of the gland. It runs forward and slightly downward on masseter.
 
Relations
  • Superiorly: Accessory parotid gland, upper buccal branch of facial nerve and transverse facial vessels.
  • Inferiorly: Lower buccal branch of facial nerve.
    At the anterior border of masseter it turns medially and pierces:
    1. Buccal pad of fat.
    2. Buccopharyngeal fascia.
    3. Buccinator.
      Because of oblique course of duct through buccinator inflation of duct is prevented during blowing. The duct run forwards for a short distance between the buccinator and oral mucosa. Finally the duct turn medially and opens in vestibule of mouth opposite the crown of upper second molar tooth.
Q.4. Describe parotid under the following headings. (a) Gross anatomy with nerve supply (b) Histology and Development (in brief).
(Apr 2008, 8 Marks)
Ans. For gross anatomy with nerve supply refer to Ans 1 of the same chapter. For histology refer to Ans 17 and 18 of HISTOLOGY SECTION.
Development: The parotid gland is an elongated furrow running dorsally from angle of mouth between mandibular and maxillary prominences.
The groove which is converted into a tube looses its connection with the epithelium of mouth, except at its ventral end, and grows dorsally into substance of cheek. The tube persist as parotid duct and its blind end proliferates in the local mesenchyme to form gland. Subsequently size of oral fissure is reduced by partial fusion between maxillary and mandibular prominences and duct opens thereafter on inside of cheek at some distance from angle of mouth.
Q.5. Write in short on parotid gland.
(Jan 2012, 5 Marks)
Ans. Refer to Ans 1 of the same chapter.
Q.6. Describe parotid gland under following heading:
(Feb 2013, 10 Marks)
a. Introduction
b. Capsule
c. Relations
d. Development
e. Histology
Ans. Introduction
  • Parotid is the largest of the salivary glands.
  • It weighs about 15 g.
  • It is situated below the external acoustic meatus, between the ramus of the mandible and sternomastoid.
  • The gland overlaps these structures. Anteriorly, the gland overlaps the masseter muscle. A part of this forward extension is often detached, and is known as the accessory parotid and it lies between the zygomatic arch and the parotid duct.
For capsule refer to Ans 1 of same chapter.
For relations refer to Ans 1 of same chapter.
For development refer to Ans 5 of same chapter.
For histology refer to Ans 17 and 18 of HISTOLOGY SECTION.
Q.7. Describe parotid gland under following heads: Nerve supply, histology, structures within the gland.
(June 2010, 15 Marks)
Ans. For nerve supply refer to Ans 1 of same chapter.
For histology refer to Ans 17 and 18 of HISTOLOGY SECTION.
 
Structures within the Gland
Structures within the parotid gland from medial to lateral side are:
  1. Arteries: Refer to Ans 1 of same chapter
  2. Veins: Refer to Ans 1 of same chapter
  3. Facial Nerve: Refer to Ans 1 of same chapter.
Q.8. Write very short answer on parotid duct opening.
(Aug 2018, 2 Marks)
Ans. Parotid duct pierces the buccinator muscle and then opens into the oral cavity on the inner surface of cheek, usually opposite the maxillary second molar tooth.
Parotid papilla is a small elevation of tissue that marks opening of the parotid duct on the inner surface of cheek.
 
7. TEMPORAL AND INFRATEMPORAL REGION
Q.1. Describe muscles of mastication under following headings, i.e. origin, insertion, relation, nerve supply, action with short note on its development.
(Apr 2010, 20 Marks)
Or
Describe muscles of mastication in detail.
(May/June 2009, 15 Marks)
Or
Describe muscles of mastication.
(Sep 2017, 10 Marks)
Or
39Name the muscles of mastication. Tabulate them under following headings: a. origin, b. course, c. insertion, d. blood supply, e. nerve supply, f. action.
(Aug 2016, 10 Marks) (Jan 2018, 10 Marks)
Or
Enumerate muscles of mastication. Give origin, insertion, nerve supply.
(Mar 2000, 6 Marks)
Or
Enumerate the muscles of mastication. Describe origin, insertion, nerve supply and action of anyone of them.
(Aug 2011, 10 Marks)
Or
Enumerate muscles of mastication. Give origin, insertion, nerve supply and action of massater muscle
(Feb 2016, 10 Marks)
Or
Write a short note on muscles of mastication.
(Aug 2018, 5 Marks)
(Jan 2012, 5 Marks)
Or
Write a note on muscles of mastication.
(Mar 2007, 4 Marks)
Or
Write about muscles of mastication.
(Dec 2014, 5 Marks)
Or
Write short answer on muscles of mastication.
(Apr 2018, 3 Marks)
Or
Describe action and nerve supply of muscles of mastication.
(Feb 2004, 10 Marks)
Or
Enumerate the muscles of mastication. Describe lateral pterygoid muscle.
(Aug 2012, 10 Marks)
Or
Write short note on temporalis muscle.
(Feb 2013, 5 Marks)
Or
Write in short on medial pterygoid muscle.
(Dec 2009, 5 Marks)
Or
Write short note on medial pterygoid muscle.
(Feb 2016, 3 Marks)
Or
Write short note on lateral pterygoid muscle.
(June 2010, 5 Marks) (Oct 2014, 3 Marks) (Dec 2010, 5 Marks)
Or
Write short answer on relations of lateral pterygoid.
(Aug 2018, 3 Marks)
Ans. Enumeration of muscles of mastication
  • Massater
  • Temporalis
  • Lateral pterygoid
  • Medial pterygoid
Muscles of mastication
Muscle
Origin
Course
Insertion
Blood supply
Relations
Nerve supply
Action
Masseter
It is quadrilateral in shape and covers lateral surface of ramus of mandible.
It has three layers
  1. Superficial layer: From anterior 2/3 of lower border of zygomatic arch and adjoining zygomatic process of maxilla
  2. Middle layer: From lower border of posterior 1/3 of zygomatic arch
  3. Deep layer: From deep surface of zygomatic arch
  • Superficial fibers pass downward and backward at 45°
  • Middle fibers pass vertically downwards
  • Deep fibers pass vertically downwards
  1. Superficial layer: Into lower part of lateral surface of ramus of mandible
  2. Middle layer: Into central part of ramus of mandible
  3. Deep layer: Into rest of ramus of mandible
It is supplied by masseteric artery
  • Superficially: Are skin, platysma, risorius, zygomaticus major, and parotid gland duct, facial nerve and transverse facial vessels cross the muscle
  • Medially: Temporalis and Mandibular ramus. Fat separates it anteriorly from buccinator. The massetric nerve and artery
  • Posteriorly: Margin is overlapped by the parotid gland, anterior margin projects over buccinator and is crossed below by facial vein.
Masseteric nerve, branch of anterior division of mandilbular nerve
  1. Elevates mandible to close the mouth to bite
  2. Superficial fibers cause protrusion
40
Temporalis
It is fan shaped and fills temporal fossa
  1. Temporal fossa
  2. Temporal fascia
Anterior fibers run vertically, middle fibers obliquely and posterior fibers horizontally. All of them converge and pass through a gap deep to zygomatic arch
  1. Margins and deep surface of coronoid process
  2. Anterior border of ramus of mandible
It is supplied by the anterior and posterior deep temporal arteries which are branches of the internal maxillary artery
  • Superficial: Skin, auricularis anterior and superior, temporal fascia, superficial temporal vessels, auricular temporal nerve, temporal branches of facial nerve, zygomaticotemporal nerve, apocranial aponeuresis, zygomatic arch and masseter
  • Medial: Temporal fossa, lateral pterygoid, superficial head of medial pterygoid, a small part of buccinator, the maxillary artery and its deep temporal branches, deep temporal nerves and buccal nerve and vessels
  • Posterior: The tendon, massetric vessels and nerve that traverse the mandibular incisure. Fat separates its anterior border from the zygomatic bone
Two deep temporal branches from anterior division of mandibular nerve
  1. Elevates mandible
  2. Posterior fibers retract protruded mandible
  3. Helps in side to side grinding movement
Lateral pterygoid
It is short and conical, it consists of upper and lower heads
  1. Upper head: From intratemporal surface and crest of greater wing of sphenoid bone
  2. Lower head: From lateral surface of lateral pterygoid plate. Origin is medial to insertion
Fibers run backward and laterally and converge for insertion
  1. Pterygoid fovea on the anterior surface of neck of mandible
  2. Anterior margin of articular disc and capsule of temporo-mandibular joint
  3. Insertion is posterolateral and is at higher level than origin
It is supplied by pterygoid branches of maxillary artery
Superficial
  • Masseter
  • Ramus of mandible
  • Tendon of temporalis
  • Maxillary artery
Deep
  • Mandibular nerve
  • Middle meningeal artery
  • Sphenomandibular ligament
  • Deep head of the medial pterygoid
Structures Emerging at the Upper Border
  • Deep temporal nerves
  • Masseteric nerve
Structures Emerging at the Lower Border
  • Lingual nerve
  • Inferior alveolar nerve
  • The middle meningeal artery passes upwards deep to it
A branch from anterior division of mandibular nerve
  1. Depresses mandible to open mouth with suprahyoid muscle
  2. Lateral and medial pterygoid protrude mandible
  3. Left lateral pterygoid and right medial pterygoid turn the chin to left side as a part of grinding movement
41
Structures passing through the Gap between two heads
  • Maxillary artery enters the gap
  • Buccal branch of the mandibular nerve comes out via gap
Pterygoid plexus of veins surrounds the lateral pterygoid
Medial pterygoid
It is quadrilateral and has a small superficial and a large deep head
  1. Superficial head: From tuberosity of maxilla and adjoining bone
  2. Deep head: From medial surface of lateral pterygoid plate and adjoining process of palatine bone
Fibers run downwards, backwards and laterally
Roughned area of medial surface of angle and adjoining ramus of mandible below and behind mandibular foramen and mylohyoid groove
It is supplied by pterygoid branches of maxillary artery
Superficial and deep heads of medial pterygoid enclose the lower head of lateral pterygoid muscle.
Superficial relations
The upper part of the muscle is separated from the lateral pterygoid muscle by:
  • Lateral pterygoid plate
  • Lingual nerve
  • Inferior alveolar nerve.
Lower down the muscle is separated from the ramus of mandible by the lingual and inferior alveolar nerves, maxillary artery, and sphenomandibular ligament.
Deep relations
The relations are:
  • Tensor veli palatine
  • Superior constrictor of pharynx
  • Styloglossus
  • Stylopharyngeus attached to the styloid process.
Nerve to medial pterygoid, branch of the main trunk of mandibular nerve
  1. Elevates mandible
  2. Helps in protruding mandible
  3. Right medial pterygoid with left lateral pterygoid turn the chin to left side
zoom view
Fig. 54: Masseter muscle (superficial layer)
zoom view
Fig. 55: Masseter muscle (deeper layer)
42
zoom view
Fig. 55: Temporalis muscle
zoom view
Fig. 56: Lateral pterygoid muscle
zoom view
Fig. 57: Medial pterygoid muscle
 
Development of Muscles of Mastication
Embryologically, the muscles of mastication develop from the first pharyngeal arch or mandibular arch. Consequently they are innervated by the mandibular nerve.
Q.2. Write a short note on branch of maxillary artery.
(Aug 2011, 6 Marks)
Or
Enumerate the branches of maxillary artery.
(Jan 2012, 3 Marks)
Ans. Introduction: This is the larger terminal branch of external carotid artery given off behind the neck of mandible. It has wide territory of distribution and supplies external and middle ears and auditory tube, dura mater, upper and lower jaws, muscles of temporal and infratemporal regions, nose and paranasal air sinuses, palate, roof of pharynx. Maxillary artery is divided into three parts, i.e. mandibular part, pterygoid part and pterygopalatine part.
 
Branches of Maxillary Artery
  1. First part, i.e. mandibular part
    1. Deep auricular artery: Supplies to external auditory meatus, tympanic membrane and temporomandibular joint.
    2. Anterior tympanic branch: Supplies to middle ear.
    3. Middle meningeal artery
    4. Accessory meningeal artery: Supplies to infratemporal fossa.
    5. Inferior alveolar artery: Supplies to mandible
  2. Second part, i.e. pterygoid part
    It consists of:
    1. Masseteric: Supplies to massater muscle
    2. Deep temporal: Supplies to both branches of temporalis
    3. Pterygoid: Supplies to lateral and medial pterygoid
    4. Buccal: Supplies to skin of cheek.
  3. Third part, i.e. pterygopalatine part
    1. Posterior superior alveolar artery: It gives branches which supply to molars, premolars and maxillary air sinus.
    2. Infraorbital artery: It supplies to orbit, incisors and canine. It also gives branches to lacrimal sac, nose and upper lip.
    3. Greater palatine artery: The branches of artery supply to the gums.
    4. The pharyngeal branch: Its supplies to part of nasopharynx auditory tube and sphenoidal air sinus.
    5. The artery of pterygoid canal: It supplies to pharynx, auditory tube and tympanic cavity.
    6. The sphenopalatine artery: The branches of artery supplies to the paranasal air sinuses and posterior septal branches to the nasal septum.43
zoom view
Fig. 59: Branches of maxillary artery
Q.3. Describe temporomandibular joint.
(Sep 2002, 10 Marks) (Apr 2003, 10 Marks)
(Aug 2011, 10 Marks) (Dec 2014, 10 Marks)
(Aug 2018, 10 Marks) (Apr 2008, 15 Marks)
Or
Describe the temperomandibular joint. Add a note on applied part.
(Aug 2012, 10 Marks) (Oct 2014, 8 Marks)
Or
Describe TM joint and its applied aspects.
(Dec 2010, 15 Marks)
Or
Describe the temporomandibular joint and give its clinical anatomy.
(Apr 2015, 8 Marks)
Or
Describe temporomandibular joint under following heads:
(May 2017, 10 Marks)
a. Type, b. Articular surfaces, c. Ligaments, d. Movements and muscle producing movements, e. Nerve and blood supply
Or
Write in short on temperomandibular joint.
(July 2016, 5 Marks)
Or
Write a short note on TM joint.
(June 2010, 5 Marks)
Or
Describe movements of temporomandibular joint.
(Sep 2001, 6 Marks)
(Mar 2008, 3 Marks) (May/June 2009, 5 Marks)
Or
Write short note on movements of temporomandibular joint.
(Apr 2007, 4 Marks) (Nov 2008, 5 Marks)
Or
Describe temporomandibular joint and add a note on its applied anatomy.
(Sep 2000, 10 Marks)
Or
Describe temporomandibular joint. Give its applied aspect.
(Jan 2018, 10 Marks)
(Jan 2012, 10 Marks)
Or
Enumerate relations of temporomandibular joint.
(Sep 2006, 5 Marks)
Or
Write a short note on ligaments of temporomandibular joint.
(Sep 2017, 2 Marks)
Or
Write short note on movements of TM joint.
(Aug 2018, 5 Marks)
Ans. Type B
This is a synovial type of condylor variety joint.
It consists of following parts of temporal bone forms upper articular surface, i.e.
  • 44The articular tubercle
  • Anterior part of mandibular fossa
  • Posterior non-articular part is formed by tympanic plate.
Inferior articular surface is formed by the head of mandible.
Fibrocartilage covers the articular surfaces.
Intra-articular disc divides joint cavity into upper and lower parts.
 
Ligaments of Temporomandibular Joint
Following are the ligaments of temporomandibular joint:
  • Fibrous capsule: It is attached above the articular tubercle, in front by circumference of mandibular fossa behind by squamotympanic fissure and below to neck of mandible. Above intra–articular disc the capsule is loose and below it is tight. Synovial membrane lines the fibrous capsule and neck of mandible.
  • Lateral temporomandibular ligament: It reinforces and provides strength to lateral part capsular ligament. Fibers of ligament are directed downwards and backwards. Ligament is attached above to articular tubercle and below to posterolateral aspect of ramus of mandible.
  • Sphenomandibular ligament: This is an accessory ligament which lies on deep plane away from fibrous capsule. The ligament is attached superiorly to spine of sphenoid and inferiorly to lingula of mandibular foramen. This is the remnant of dorsal part of Meckle's cartilage.
    • This ligament is related laterally to lateral pterygoid muscle, auriculotemporal nerve and maxillary artery while it is related medially to chorda tympani nerve and wall of pharynx. Near its lower end, it is pierced by mylohyoid nerve and vessels.
  • Stylomandibular ligament: This is another accessory ligament of joint. This ligament represents the thick part of deep cervical fascia which causes the separation of parotid and submandibular salivary glands. This ligament is attached above to lateral surface of styloid process and below to angle as well as adjacent part of posterior border of ramus of mandible.
 
Articular Disc
  • It is an oval fibrous plate which divides joint upper and lower compartments.
  • Upper compartment leads to gliding movements and the lower compartment leads to both, i.e. rotatory as well as gliding movements.
  • Disc consists of concave–convex superior surface and concave inferior surface.
  • Periphery of articular disc gets attached to fibrous capsule.
  • It also consists of an anterior extension, anterior thick band, intermediate zone, posterior thick band and bilaminar region which consists of venous plexus
  • It prevents the friction between articulating surfaces.
  • It act as a cushion and absorbs the shock. It also stabilizes the condyle by filling the space between articular surfaces.
  • Proprioceptive fibers present inside the disc regulate movements of joint.
  • Disc also distributes the weight across temporomandibular joint by enhancing area of contact.
 
Relations of Temporomandibular Joint
  • Lateral: Skin and fasciae, parotid gland and temporal branches of facial nerve.
  • Medial: Tympanic plate separates the joint from internal carotid artery, spine of sphenoid with upper end of sphenomandibular ligament attached to it, auriculotemporal and chorda tympani nerves, middle meningeal artery.
  • Anterior: Lateral pterygoid, masseteric nerve and artery.
  • Posterior: Parotid gland separates joint from external auditory meatus, superficial temporal vessels and auriculotemporal nerve.
  • Superior: Middle cranial fossa and middle meningeal vessels.
  • Inferior: Maxillary artery and vein.
 
Blood Supply
It is supplied by the branches from superficial temporal and maxillary arteries, veins usually follow arteries.
 
Nerve Supply
Temporomandibular joint is supplied by the auriculotemporal nerve and masseteric nerve.
 
Lymphatic Drainage
Lymph from temporomandibular joint drains into:
  • Superficial parotid nodes
  • Deep parotid nodes
  • Upper deep cervical nodes.
 
Movements of Temporomandibular Joint
When temporomandibular joint of both the sides are in position of rest, there exist a small free space between maxillary and mandibular teeth but lips are in contact. Various movements of mandible occur in this position.
Lower jaw can be depressed, elevated, protruded, retracted and move from side to side due to movements of temporomandibular joint.
 
Mechanism
There are two basic movements which occur at temporomandibular joint but with the help of muscles. Two basic movements are gliding movement and rotational movement.
  • Upper meniscotemporal compartment of temporomandibular joint leads to gliding movements at the time of protraction, retraction and chewing.
  • Lower meniscotemporal compartment permit rotation around two axis, i.e. transverse axis at the time of depression and elevation and vertical axis at the time of side to side (chewing) movements.
  • Movements occurring at temporomandibular joints are:
    • Depression (lowering of jaw to open the mouth): During depression, head of mandible along with 45articular disc glide forward in upper meniscotemporal compartment on both the sides by contraction of lateral pterygoid muscle. During same time head rotates forward underneath the articular disc due to contraction of suprahyoid muscles, i.e. digastrics geniohyoid and mylohyoid. Gravity also provides help in opening the mouth.
    • Elevation (elevating of jaw to close the mouth): At the time of elevation, movements take place in a reverse order to that take place in depression, i.e., first head of mandible along with an articular disc glide backward in the upper meniscotemporal compartment by temporalis, masseter, and medial pterygoid, and then head rotates backward on the lower surface of the disc by posterior fibers of temporalis.
    • Protrusion/protraction: In protrusion, mandibular teeth move forward in front of maxillary teeth. In this act, head of the mandible along with the articular disc glide forwards in the upper meniscotemporal compartment on both sides by simultaneous action of medial and lateral pterygoids of both sides.
    • Retraction: In retraction, head of mandible along with articular disc glide backwards in the upper meniscotemporal compartment by the contraction of posterior fibers of temporalis muscle and bring the joint in the resting position. The retraction is assisted by deep fibers of masseter, digastric, and geniohyoid muscles. During end of this movement head of the mandible comes to lie underneath the articular tubercle.
    • Side-to-side (Chewing) movements: These movements take place alternately in the right and left temporomandibular joints. During chewing movements, head of the mandible on one side glides forwards along with the disc (as in protraction), but the head of the mandible on the opposite side merely rotates on the vertical axis. Due to which the chin moves forwards and to one side, i.e. towards the side on which no gliding has taken place. In this movement, the medial and lateral pterygoids of one side contract alternatively with those of opposite sides.
      Alternate movements of this kind on the two sides result in side-to-side movements of the lower jaw.
 
Muscles Producing Movements of Temporomandibular Joint
  • Depression (opening of mouth): This is caused mainly by lateral pterygoid. Digastric, geniohyoid and mylohyoid muscles help when mouth is opened wide or against resistance.
  • Elevation: It is caused by medial pterygoid muscle of both sides, masseter, and anterior, vertical and middle oblique fibers of temporalis muscle. These are antigravity muscles.
  • Protrusion: It is done by lateral and medial pterygoids as well as superficial oblique fibers of massater muscle.
  • Retraction: It is carried out by posterior horizontal fibers of temporalis and deep vertical fibers of massater.
  • Lateral or side to side or chewing movements: It is carried out by alternate contraction of medial and lateral pterygoids of each side. For e.g. chewing from left side is produced by right lateral pterygoid, right medial pterygoid which pushes the chin over left side. Now left temporalis, left massater chew food. Chewing over the right side involve left lateral pterygoid, left medial pterygoid, right temporalis and right massater.
 
Applied Anatomy or Clinical Anatomy
  • Dislocation of mandible: During excessive opening of mouth or during a convulsion, the head of the mandible of one or both sides may slip anteriorly into infratemporal fossa due to which there is inability to close the mouth. Reduction is done by depressing the jaw with thumb placed on last molar teeth and at same time elevating the chin.
  • Derangement of articular disc may result from any injury, like overclosure or malocclusion which causes clicking and pain during movements of jaw.
  • In operations on temporomandibular joint facial nerve as well as auriculotemporal nerve, branch of mandibular division of trigeminal nerve should be preserved with care.
zoom view
Fig. 60: Temporomandibular joint
Q.4. Mention distribution of mandibular nerve and its applied anatomy in reference to neuralgia.
(Feb 2002, 10 Marks)
Or
Give an account of course, relation and branches of mandibular nerve. Add a note on “trigeminal neuralgia”.
(Sep 2000, 18 Marks)
Or
Describe mandibular nerve in detail.
(Mar 2006, 15 Marks) (Nov 2008, 15 Marks)
Or
Describe mandibular nerve with its applied anatomy.
(Nov 2008, 5 Marks)
Or
Describe the course and branches of the mandibular nerve.
(Apr 2008, 8 Marks)
Or
Enumerate the branches of mandibular nerve.
(Apr 2007, 3 Marks)
46Or
Describe the course and distribution of mandibular nerve.
(Sep 2007, 8 Marks)
Or
Describe anatomy of mandibular division of trigeminal nerve.
(June 2010, 10 Marks)
Or
Write short note on mandibular nerve.
(July 2016, 5 Marks) (Aug 2012, 5 Marks)
Or
Describe briefly ligaments of temporomandibular joint.
(Jan 2012, 5 Marks)
Or
Describe mandibular nerve under following heads:
(Mar 2013, 2+2+2+2 Marks)
a. Formation
b. Course and relation
c. Branches
d. Applied anatomy
Or
Describe course, relation, branches and applied anatomy of mandibular nerve.
(Feb 2014, 2+2+2+2 Marks)
Or
Describe mandibular nerve with its applied anatomy.
(May 2014, 10 Marks)
Or
Write branches and distribution of mandibular nerve with a note on applied anatomy.
(Sep 2015, 10 Marks)
Or
Write short answer on branches of mandibular nerve.
(Aug 2018, 3 Marks)
Ans. Mandibular nerve is the largest mixed branch of trigeminal nerve.
 
Formation of Mandibular Nerve
Mandibular nerve arises from the trigeminal nerve. It is a mixed nerve with two roots—a large sensory root and a smaller motor root. Sensory root of the mandible division originates at the inferior angle of trigeminal ganglion, whereas motor root arises in motor cells located in pons and medulla oblongata. Two roots emerge from cranium separately through foramen ovale, the motor root lying medial to sensory. They unite just outside the skull and form main trunk of third division. The trunk remains undivided for only 2 to 3 mm before it splits into small anterior and larger posterior division.
 
Course or Distribution and Relations
Mandibular nerve starts from middle cranial fossa by large sensory root and small motor root. Sensory root emerges from the lateral part of trigeminal ganglion and leaves cranial cavity via foramen ovale. Motor root lies deep to trigeminal ganglion and to sensory root. It passes via foramen ovale and join sensory root below the foramen forming main trunk. Main trunk lies in infratemporal fossa over tensor veli palatine, deep to lateral pterygoid muscle. After a short distance main trunk divides into small anterior trunk and large posterior trunk.
 
Branches of Mandibular Nerve
  • From the main trunk
    • Meningeal branch.
    • Nerve to medial pterygoid.
  • From anterior trunk
    • Sensory branch: Buccal nerve.
    • Motor branch: Masseteric, deep temporal and nerve to lateral pterygoid.
  • From posterior trunk
    • Auriculotemporal nerve
    • Lingual nerve
    • Inferior alveolar nerve.
From the Main Trunk
Meningeal Branch or Nervous Spinosus
It enters skull via foramen spinosum along with middle meningeal artery and supplies dura mater of middle cranial fossa.
Nerve to Medial Pterygoid
It arises close to otic ganglion and supply medial pterygoid from its deep surface. It gives motor root to otic ganglion which does not relay and supply tensor palati muscle and tensor tympani muscle.
From Anterior Trunk
All the branches are motor except buccal which is sensory.
Buccal Nerve
This nerve is the only sensory branch of anterior division of mandibular nerve. This nerve passes between two heads of lateral pterygoid, run downward and forward and supply to skin of cheek and mucus membrane which is related to buccinator. Labial aspect of gingiva of molar and premolar teeth is supplied by buccal nerve.
Masseteric Nerve
It emerges at upper border of lateral pterygoid muscle mainly in front of temporomandibular joint. It passes laterally via mandibular notch in company with masseteric vessels and enters deep surface of massater. Temporomandibular joint is also supplied by this nerve.
Deep Temporal Nerve
They are two in number, i.e. anterior and posterior. These nerves pass between the skull and lateral pterygoid. It enters at deep surface of temporalis.
47Nerve to Lateral Pterygoid
It runs with the buccal nerve and enters deep surface of both heads of lateral pterygoid muscle which it supplies.
From Posterior Trunk
Auriculotemporal Nerve
It arises by two roots which run backwards and encircle the middle meningeal artery and unite to form a single trunk. It continues backward between neck of mandible and sphenomandibular ligament above the maxillary artery. Behind the neck of mandible it turn upward and ascend on temple behind superficial temporal vessels.
  • Auricular part of nerve supplies skin of tragus, upper parts of pinna, external acoustic meatus and tympanic membrane.
  • Temporal part supplies skin of temple
  • In addition auriculotemporal nerve also suppliesparotid gland and temporomandibular joint.
Lingual Nerve
  • It is one of the two terminal branches of the posterior division of the mandibular nerve.
  • It is sensory to the anterior two-third of the tongue and to the floor of the mouth.
  • However, the fibers of the chorda tympani (branch of facial nerve) which is secretomotor to the submandibular and sublingual salivary glands and gustatory to the anterior two-third of the tongue are also distributed through the lingual nerve.
Course and Relations
It begins just l cm below the skull. It runs first between the tensor palati and lateral pterygoid, and then between the lateral and medial pterygoids. About 2 cm below the skull it is joined by the chorda tympani nerve. Emerging at the lower border of the lateral pterygoid, the nerve runs downwards and forwards between the ramus of the mandible and the medial pterygoid. Next it lies in direct contact with the mandible, medial to the third molar tooth. It soon leaves the gum and runs over the hyoglossus deep to the mylohyoid. Finally it lies on the surface of the genioglossus deep to the myelohyoid. Here it winds round the submandibular duct and divides into its terminal branches.
Inferior Alveolar Nerve
It is the larger terminal branch of posterior division of mandibular nerve. It run vertically downwards lateral to medial pterygoid and to the sphenomandibular ligament. The nerve enters the mandibular foramen and runs inside the mandibular canal. It is accompanied by inferior alveolar artery.
Branches
  • Mylohyoid branch consists of all the motor fibers of posterior division. The nerve arises just before the inferior alveolar nerve and enters the mandibular foramen. It also pierces sphenomandibular ligament along with mylohyoid artery, runs in the mylohyoid groove, and supplies mylohyoid muscle and anterior belly of the digastric.
  • During running inside the mandibular canal, the inferior alveolar nerve gives off the branches that supply the lower teeth and gums.
  • Mental nerve emerges at the mental foramen and supplies to skin of chin and the skin as well as mucous membrane of the lower lip. Its incisive branch supplies to labial aspect of gums of canine and incisor teeth.
 
Applied Anatomy
  • A lesion at foramen ovale involves mandibular nerve and causes paresthesia along the mandible, in mandibular teeth and side of the face. There is also paralysis of muscles of mastication and loss of jawjerk reflex as the nerve supplies both afferent and efferent limbs for jaw jerk reflex.
  • Motor part of mandibular nerve is tested clinically by asking the patient to clench his teeth and then feeling for contracting massater and temporalis muscle on two sides. If massater of one side is paralyzed, jaw deviates to the paralyzed side, on opening the mouth by action of normal lateral pterygoid of opposite side. Activity of pterygoid muscles is tested by asking the patient to move chin from side to side.
  • In patients with the cancer of tongue pain radiates to ear and temporal fossa over the distribution of auriculotemporal nerve as both lingual and auriculotemporal nerves are branches of mandibular nerve. At times lingual nerve is divided to relieve interactable pain. This can be done where the nerve lies in contact with mandible below and behind last molar tooth and is covered by mucous membrane.
zoom view
Fig. 61: Mandibular nerve with its branches
  • Pain along the distribution of mandibular division of trigeminal nerve is known as mandibular neuralgia. The neuralgia is often difficult to treat and is treated by division of sensory root of trigeminal nerve. This is now the operation of choice when pain is confined to distribution of 48maxillary and mandibular nerves. During the division the ophthalmic fibers which lie in superomedial part of root are preserved to spare corneal reflex this avoids damage to cornea.
  • Lingual nerve lies in contact with medial to third molar tooth. In extraction of malplaced wisdom tooth, care should be taken not to injure the lingual nerve. Its injury causes loss of sensation from anterior two–third of tongue.
  • During extraction of mandibular teeth, inferior alveolar nerve should be anesthetized. Drug is given inside the nerve before it enters mandibular canal.
  • Inferior alveolar nerve travels the mandibular canal and can be damaged by the fracture of mandible. This injury is assessed by testing sensation over the chin.
  • At the time of extraction of third molar, buccal nerve may get involved by local anesthesia leading to temporary numbness of cheek.
Q.5. Write short note on otic ganglion.
(Oct 2016, 3 Marks)
(Feb 2016, 3 Marks) (Dec 2010, 5 Marks) (Mar 2000, 5 Marks) (Mar 2009, 5 Marks)
Or
Write short answer on otic ganglion.
(Apr 2018, 3 Marks)
Ans. It is a peripheral parasympathetic ganglion which relay secretomotor fibers to parotid gland. Topographically it is related to mandibular nerve but functionally it is the part of glossopharyngeal nerve.
 
Size and Location
It is usually 2 to 3 mm in size and is located inside the infra– temporal fossa below foramen ovale.
 
Relations
  • Lateral: Mandibular nerve
  • Medial: Tensor palate muscle
  • Posterior: Middle meningeal artery
  • Anterior: Medial pterygoid muscle.
 
Roots or Connections
  • The motor or parasympathetic root is formed by lesser petrosal nerve. Preganglionic fibers arise from inferior salivary nucleus. They pass through glossopharyngeal nerve, its tympanic branch, tympanic plexus and lesser petrosal nerve to reach otic ganglion. The postganglionic fibers join auriculotemporal nerve to parotid gland.
  • Sympathetic root is derived from the plexus on middle meningeal artery. It contains postganglionic fibers arising in superior cervical ganglion. Fibers pass via otic ganglion without relay and reach parotid gland via auriculotemporal nerve. They are vasomotor in function and are responsible for thick salivary secretion.
  • Sensory root comes from the auriculotemporal nerve and is sensory to parotid gland.
  • Various other fibers which pass through ganglion are:
    • Nerve to medial pterygoid provides motor root to ganglion which passes through it without relay and supply medially placed tensor veli palatine and laterally placed tensor tympani muscle.
    • Chorda tympani nerve connected to otic ganglion and also to nerve of pterygoid canal. These connections leads to an alternative pathway of taste from anterior two-third of tongue.
zoom view
Fig. 62: Otic ganglion and its connections
49Q.6. Write extracranial course of mandibular nerve. Write about its branches and distribution.
(Sep 2005, 15 Marks)
Ans. Extracranial Course
Both the roots pass through the foramen ovale and join to form the main trunk which lies in infratemporal fossa. After a short course the main trunk divides into the small anterior and a large posterior division.
For branches and distribution refer to Ans 4 of the same chapter.
Q.7. Describe in brief the mandibular nerve. Add a note on trigeminal ganglion.
(Sep 2006, 15 Marks)
Ans. For mandibular nerve in brief refer to Ans 4 of the same chapter.
 
Trigeminal Ganglion
  • Trigeminal ganglion is the sensory ganglion of the fifth cranial nerve.
  • This ganglion is homologus with dorsal nerve root ganglia of spinal nerves.
  • It is made up of pseudounipolar nerve cells with a ‘T’ shaped arrangement of their processes.
  • The ganglion is crescentric or semilunar in shape with its convexity directed anterolaterally.
    • The three divisions of trigeminal nerve emerges from this convexity.
    • The posterior concavity of the ganglion receives the sensory root of the nerve.
 
Situation and Meningeal Relation
Trigeminal ganglion lies on the trigeminal impression over anterior surface of petrous temporal bone near its apex. Here it occupies a special space of dura matter known as trigeminal cave or Meckel's cave. Two layers of dura are present below ganglion. Cave is lined by pia–arachnoid, so, the ganglion along with motor root of the trigeminal nerve is surrounded by cerebrospinal fluid. Ganglion lies at depth of 5 cm from the preauricular point.
zoom view
Fig. 63: Relation of trigeminal ganglion
 
Relations
  • Medially: Internal carotid artery and posterior part of cavernous sinus
  • Laterally: Middle meningeal artery
  • Superiorly: Parahippocampal gyrus
  • Inferiorly: Motor root of the trigeminal nerve, greater petrosal nerve, apex of petrous temporal bone and foramen lacerum.
 
Associated Root and Branches
  • Central process of ganglion cells forms the large sensory root of trigeminal nerve which is attached to pons at its junction with middle cerebellar peduncle.
  • Peripheral processes of the ganglion cells form three divisions of the trigeminal nerve, i.e. ophthalmic, maxillary and mandibular.
  • Small motor root of trigeminal nerve attach to pons superomedial to sensory root. It passes under the ganglion from medial to lateral side and joins the mandibular nerve at the foramen ovale.
 
Blood Supply
  • Internal carotid artery
  • Middle meningeal artery
  • Accessory meningeal artery
  • Meningeal branch of ascending pharyngeal artery.
 
Applied Anatomy
Intractable facial pain due to trigeminal neuralgia or carcinomatosis may be abolished by injecting alcohol into the ganglion.
Q.8. Write short note on parts of temporomandibular joint.
(Mar 2006, 5 Marks)
Ans. Temporomandibular (TMJ) joint has two types of parts:
  1. Bone or hard tissue parts
  2. Soft tissue parts.
 
Bone or Hard Tissue Parts
The hard tissue parts of TMJ are:
  • Condyles of mandible: They are ovoid, convex processes which are broader laterally and narrower medially. Condyles are connected with the body of mandible by narrow stalk on both the sides.
  • Glenoid fossa of temporal bone: Articular surface of temporal bone is situated on the inferior surface of squamous part of the temporal bone. It articulates with mandibular condyle and is known as glenoid fossa.
  • Articular eminence: It binds mandibular fossa anteriorly and form anterior root of zygomatic process.
 
Soft Tissue Parts
  • Articular capsule: It is a thin part of dense cartilaginous tissue which encloses joint cavity.
  • Articular disc: It is a rough, oval, firm, thick plate of dense fibrous cartilage which is located between condyle and articulating surface of temporal bone. It divides joint into superior and inferior compartments.
  • Articular ligaments: TMJ has one major and three minor ligaments. Temporomandibular is major ligament, while 50sphenomandibular, stylomandibular and pterygomandibular raphae are minor ligaments.
  • Muscles: Muscle which is closest to the TMJ is lateral pterygoid muscle. It helps in the protrusion of mandible.
Q.9. Describe anatomy of mandibular division of trigeminal nerve. Discuss applied anatomy of its branches.
(Oct 2007, 15 Marks)
Ans. For mandibular division of trigeminal nerve in details refer to Ans 4 of same chapter.
 
Applied Anatomy of Branches of Mandibular Division of Trigeminal Nerve
  • In patients with the cancer of tongue pain radiates to ear and temporal fossa over the distribution of auriculotemporal nerve as both lingual and auriculotemporal nerves are branches of mandibular nerve. At times lingual nerve is divided to relieve interactable pain. This can be done where the nerve lies in contact with mandible below and behind last molar tooth and is covered by the mucous membrane.
  • Lingual nerve lies in contact with medial to third molar tooth. In extraction of malplaced wisdom tooth, care should be taken not to injure the lingual nerve. Its injury causes loss of sensation from anterior two-third of the tongue.
  • During extraction of mandibular teeth, inferior alveolar nerve should be anesthetized. Drug is given inside the nerve before it enters mandibular canal.
  • Inferior alveolar nerve travels the mandibular canal and can be damaged by fracture of mandible. This injury is assessed by testing sensation over the chin.
  • At the time of extraction of third molar, buccal nerve may get involved by local anesthesia leading to temporary numbness of cheek.
Q.10. Draw diagram of distribution of maxillary nerve.
(Apr 2007, 5 Marks) (Sep 2009, 5 Marks)
Ans. Maxillary division of the trigeminal nerve is entirely sensory in function.
zoom view
Fig. 64: Distribution of maxillary nerve
The maxillary nerve originates at the middle of the semilunar ganglion.
Q.11. Write short note on lingual nerve.
(Aug 2016, 3 Marks)
(Feb 2013, 5 Marks) (Dec 2009, 5 Marks)
Or
Describe briefly lingual nerve.
(Dec 2010, 5 Marks)
Ans. It is one of the two terminal branches of the posterior division of the mandibular nerve.
  • It is sensory to the anterior two-third of the tongue and to the floor of the mouth.
  • However, the fibers of the chorda tympani (branch of facial nerve) which is secretomotor to the submandibular and sublingual salivary glands and gustatory to the anterior two-third of the tongue are also distributed through the lingual nerve.
 
Course
Lingual nerve starts 1 cm below the skull. At about 2 cm below the skull, it is joined by chorda tympani nerve at an acute angle. Then it lie in contact with mandible medial to third molar. Finally it lies over the surface of hyoglossus and genioglossus to reach the tongue.
 
Relations
It begins just l cm below the skull. It runs first between the tensor palati and lateral pterygoid, and then between the lateral and medial pterygoids. About 2 cm below the skull it is joined by the chorda tympani nerve. Emerging at the lower border of the lateral pterygoid, the nerve runs downwards and forwards between the ramus of the mandible and medial pterygoid. Next it lies in direct contact with the mandible, medial to the third molar tooth. It soon leaves the gum and runs over the hyoglossus deep to the mylohyoid. Finally it lies on the surface of the genioglossus deep to the myelohyoid. Here it winds round the submandibular duct and divides into its terminal branches.
Q.12. Write short note on nerve supply of maxillary teeth.
(Apr 2007, 5 Marks)
Ans. Maxilla is mainly supplied by maxillary nerve and its branches.
  • Anterior superior alveolar nerve supplies the pulp, investing structure and labial mucoperiosteum of central incisor, lateral incisor and canine.
  • Middle superior alveolar nerve supplies the pulp, investing structure and buccal mucoperiosteum of first and second premolars and mesiobuccal root of first molar.
  • Posterior superior alveolar nerve supplies the pulp, investing structure and buccal mucoperiosteum of maxillary first, second and third molars except mesiobuccal root of first molar.
  • Greater palatine nerve supplies palatal mucoperio-steum of maxillary first, second and third molars and first and second premolars.
  • Nasopalatine nerve supplies palatal mucoperiosteum of central incisor, lateral incisor and canine, incisive papilla and gingiva behind incisor teeth.51
zoom view
Fig. 65: Nerve supply of maxillary teeth
Q.13. Answer in brief on trigeminal neuralgia.
(Feb 2016, 2 Marks)
Ans. Trigeminal neuralgia is also known as Tic douloureux or Fothergill's Disease.
  • It is a clinical condition which is characterized by sudden paroxysmal attack of lancinating pain which lasts from few hours to several days which is confined to the distribution of one or more divisions of trigeminal nerve.
  • It commonly starts in maxillary territory.
  • It occurs more frequently on right side.
  • During attacks there is flushing of face, i.e. redness of the face.
Q.14. Write short note on sphenomandibular ligament.
(Aug 2016, 3 Marks)
Ans. This is an accessory ligament which lies on deep plane away from fibrous capsule.
  • The ligament is attached superiorly to spine of sphenoid and inferiorly to lingula of mandibular foramen.
  • This is the remnant of dorsal part of Meckle's cartilage.
  • This ligament is related laterally to:
    • Lateral pterygoid muscle
    • Auriculotemporal nerve
    • Maxillary artery
  • It is related medially to:
    • Chorda tympani nerve
    • Wall of pharynx. Near its lower end, it is pierced by mylohyoid nerve and vessels.
  • Sphenomandibular ligament is an important landmark for administration of local anesthetic during inferior alveolar nerve block.
Q.15. Name the branches of maxillary nerve.
(Aug 2016, 2 Marks)
Ans. Following are the branches of maxillary nerve:
Region
Branches
In middle cranial fossa
Meningeal branch
In pterygopalatine fossa
  • Ganglionic branches
  • Zygomatic branches, i.e. zygomaticotemporal and zygomaticofacial (sensory branches)
  • Posterior superior alveolar
In infraorbital canal
  • Middle superior alveolar
  • Anterior superior alveolar
On face
Infraorbital branches, i.e. palpebral, labial and nasal branches (sensory branches)
Q.16. Write short note on maxillary nerve.
(Apr 2017, 4 Marks)
Ans. Maxillary nerve is the second division of trigeminal is purely sensory.
 
Course and Relations
This nerve arises from convex anterior border of trigeminal ganglion and run forward in lateral wall of cavernous sinus below ophthalmic nerve. It leaves middle cranial fossa by passing via foramen rotundum. Maxillary nerve crosses upper part of pterygopalatine fossa beyond which it continues as infraorbital nerve. In middle cranial fossa it gives off meningeal branch. In pterygopalatine fossa the nerve is related to pterygopalatine ganglion and gives off ganglionic, posterior superior alveolar and zygomatic nerves.52
zoom view
Fig. 66: Origin, Course and branches of maxillary nerve
 
Branches and Distribution
In Middle Cranial Fossa
In middle cranial fossa it gives off meningeal branch which supplies dura mater of middle cranial fossa.
In Pterygopalatine Fossa
  • Ganglionic branches: Pterygopalatine ganglion is suspended by ganglionic branches and they are two in number.
  • Zygomatic nerve: It enters the orbit via inferior orbital fissure and runs along lateral wall outside periosteum to enter zygomatic bone. Before or after entering the bone it divides into two of the terminal branches, i.e. zygomaticotemporal and zygomaticofacial nerves which supply anterior part of temple and skin of face.
  • Posterior superior alveolar nerve: It enters posterior surface of body of maxilla and supply to three maxillary molar teeth and adjoining part of gum.
In the Orbit
  • Middle superior alveolar nerve: It arises in infraorbital groove, run in lateral wall of maxillary sinus and supply to maxillary premolar teeth.
  • Anterior superior alveolar nerve: It arises in infraorbital canal and run inside sinuous canal consisting of complicated course in anterior wall of maxillary sinus. The nerve supplies to maxillary incisor, canine teeth, maxillary sinus and anteroinferior part of nasal cavity.
On the Face
  • Palpebral branches turn upward and supply to skin of lower eyelid
  • Nasal branches supply to skin of side of nose and the mobile part of nasal septum
  • Superior labial branches supply to skin and mucus membrane of upper lip.
 
8. SUBMANDIBULAR REGION
Q.1. Write a short note on digastric muscle.
(Mar 2000, 4 Marks) (June 2010, 5 Marks)(Oct 2014, 4 Marks) (Jan 2012, 5 Marks)(Nov 2008, 5 Marks)
Ans. The muscle is so called because it consists of two belly which are united by an intermediate tendon.
 
Origin
  • Anterior belly from digastric fossa of mandible.
  • Posterior belly from mastoid notch of temporal bone.
 
Fibers
  • Anterior belly run downward and backward.
  • Posterior belly run downward and forward.
zoom view
Fig. 67: Digastric muscle
 
53Insertion
Both the heads meet at intermediate tendon which perforates stylohyoid and is held by fibrous pulley to hyoid bone.
 
Nerve Supply
  1. Anterior belly by nerve to mylohyoid branch of trigeminal nerve
  2. Posterior belly by facial nerve.
 
Action
  • It depresses mandible when mouth is wide opened or against the resistance; it is secondary to lateral pterygoid muscle.
  • It leads to elevation of hyoid bone.
 
Relations of Posterior Belly
  1. Superficial relation:
    • Mastoid process with sternomastoid, splenius capitis and longissimus capitis
    • Stylohyoid
    • Parotid gland with retromandibular vein
    • Submandibular salivary gland and lymph nodes
    • Angle of mandible with medial pterygoid.
  2. Deep relation:
    • Transverse process of atlas with superior oblique and rectus capitis lateralis
    • Internal carotid, external carotid, lingual, facial and occipital arteries
    • Internal jugular vein
    • 10th, 11th and 12th cranial nerves
    • Hyoglossus muscle.
  3. Its upper border is related to:
    1. Posterior auricular artery
    2. Stylohyoid muscle.
  4. Lower border is related to occipital artery.
zoom view
Fig. 68: Relations of posterior belly of digastric muscle
Q.2. Write a short note on mylohyoid muscle.
(Sep 2000, 4 Marks) (Feb 2016, 3 Marks)
Ans. This is a flat triangular muscle lying deep to the anterior belly of digastric. The right and left mylohyoid muscles together form the floor of mouth, deep to anterior belly of digastric.
 
Origin
From mylohyoid line of mandible.
 
Fibers
Fibers run medially and slightly downwards.
 
Insertion
  • Posterior fibers are inserted into the body of hyoid bone
  • Anterior and middle fibers are inserted into median raphae between mandible and hyoid bone.
 
Nerve Supply
It is supplied by mylohyoid nerve.
 
Actions
  • Elevates the floor of mouth during first stage of deglutition.
  • Helps in depression of mandible and elevation of hyoid bone.
 
54Relations
Superficial
  • Anterior belly of digastric
  • Superficial part of submandibular salivary gland
  • Mylohyoid nerve and vessels
  • Submental branch of facial artery.
Deep
  • Hyoglossus with its superficial relations, i.e. styloglossus, lingual nerve, submandibular ganglion, deep part of submandibular salivary gland, submandibular duct, hypoglossal nerve and venae comitantes hypoglossi.
  • Genioglossus with its superficial relations sublingual salivary gland, lingual nerve, submandibular duct, lingual artery and hypoglossal nerve.
Q.3. Write a short note on superficial relations of hyoglossus muscle.
(Sep 2017, 3 Marks)
(Sep 2004, 5 Marks)
Ans. Superficial relations of hyoglossus muscles are:
Styloglossus, lingual nerve, submandibular ganglion, deep part of submandibular gland, submandibular duct, hypoglossal nerve and veins accompanying it.
  • Styloglossus muscle interdigitates with hyoglossus.
  • Lingual nerve crosses the upper part of muscle from behind forwards
  • Submandibular ganglion lies between lingual nerve and deep part of submandibular gland.
  • Deep part of submandibular gland and submandibular duct. Gland lies in middle of hyoglossus muscle and duct lies between the gland and muscle.
  • Hypoglossal nerve crosses lower part of muscle from behind forwards.
For diagram of superficial relations of hyoglossus refer to Ans 5 of the same chapter.
Q.4. Write a short note on hyoglossus muscle.
(Sep 2001, 4 Marks) (Apr 2017, 4 Marks)
(Dec 2012, 3 Marks) (Aug 2012, 5 Marks)
(Dec 2014, 5 Marks) (Apr 2008, 5 Marks)
Ans. Hyoglossus is a thin quadrilateral muscle and is a muscle of tongue.
Origin: It originates from whole length of greater cornua and in front of lateral part of body of hyoid bone.
Fibers and insertion: The fibers run upwards and forwards and are inserted into side of tongue between styloglossus and inferior longitudinal muscle of tongue.
Action: It depresses the tongue, make dorsum convex and helps in retracting protruded tongue.
 
Relation
  1. Superficial: The relations are mentioned in Ans 3 of the same chapter.
  2. Deep:
    • Inferior longitudinal muscle of tongue
    • Genioglossus
    • Middle constrictor of pharynx
    • Glossopharyngeal nerve
    • Stylohyoid ligament
    • Lingual artery
    The diagram of superficial relation is mentioned in Ans 5 of the same chapter.
    Structures passing deep to posterior border of hyoglossus from above downwards.
    • Glossopharyngeal nerve
    • Stylohyoid ligament
    • Lingual artery
zoom view
Fig. 69: Hyoglossus muscle
Q.5. Draw a well labeled diagram showing superficial relations of hyoglossus muscle.
(Oct 2014, 4 Marks)
Ans.
zoom view
Fig. 70: Superficial relation of hyoglossus
Q.6. Describe submandibular gland. Write a note on its secretomotor fibers.
(Sep 2002, 10 Marks)
Or
Write a short note on secretomotor pathway for submandibular salivary gland.
(Sep 2000, 4 Marks)
55Or
Describe submandibular salivary gland under headings:
(Apr 2003, 10 Marks)
a. Deep relation
b. Innervations
Ans. The submandibular gland is a large salivary gland situated in anterior part of digastric triangle. It is of J-shaped. It is divided into larger part superficial to muscles, and smaller part deep to muscles. It lies in mandible bone under submandibular fossa.
 
Superficial Part
The part fills digastric triangle. It extends upward deep to mandible upto mylohyoid line. It has inferior, lateral and medial surfaces. The gland is partially enclosed between two layers of deep cervical fascia.
Superficial layer of fascia cover the inferior surface of gland and is attached to, base of mandible while the deeper layer covers medial surface of gland and is attached to mylohyoid line of mandible.
Relations of Superficial Part
  • The inferior surface: It is covered by:
    • Skin
    • Platysma
    • Cervical branch of facial nerve
    • Deep fascia
    • Facial vein
    • Submandibular lymph nodes.
  • The lateral surface: It is related to:
    • Submandibular fossa on mandible
    • Insertion of medial pterygoid
    • Facial artery.
zoom view
Fig. 71: Relations of superficial surface as well as relations of anterior part of medial surface
  • The medial surface: It is extensively divided to three parts:
    1. Anterior part is related to mylohyoid muscle, submental branch of facial artery mylohyoid nerves and vessels.
    2. Middle part (intermediate part) is related to hyoglossus muscle, styloglossus muscle, lingual nerve, submandibular ganglion and hypoglossal nerve.
    3. Posterior part is related to styloglossus muscle, stylohyoid ligament, the glossopharyngeal nerve and the wall of pharynx.
zoom view
Fig. 72: Relations of medial surface of submandibular salivary gland
 
56Deep Part
It lies deep to mylohyoid, and superficial to hyoglossus and styloglossus. Posteriorly, it is continuous with superficial part round the posterior border of mylohyoid. Anteriorly it extend to posterior end of sublingual gland.
Relations of Deep Part
They are present between mylohyoid and hyoglossus:
  • Medially it is related to hyoglossus muscle
  • Laterally it is related to the mylohyoid muscle
  • Superiorly it is related to lingual nerve and submandibular ganglion
  • Inferiorly it is related to hypoglossal nerve.
zoom view
Fig. 73: Relations of deep part of submandibular salivary gland
Blood supply: It is supplied by facial artery. Veins drain into common facial vein and lingual vein.
Lymphatic drainage: Lymph passes to submandibular lymph nodes.
Nerve supply or innervations: It is supplied by branch from submandibular ganglion.
The branches convey:
  1. Secretomotor fibers.
  2. Sensory fibers from lingual nerve.
  3. Sympathetic fibers from plexus on facial artery.
 
Secretomotor Pathway
  • Secretomotor fibers pass from the lingual nerve to the ganglion through the posterior root. These are preganglionic fiber that arise in superior salivary nucleus and pass through the facial nerve, chorda tympani and lingual nerve to reach the ganglion. The fibers relay in ganglion. Postganglionic fibers for the submandibular gland reach the gland through five or six branches from the ganglion. Postganglionic fibers for sublingual and anterior lingual glands re-enter the lingual nerve through the anterior root and travel to gland through distal part of lingual nerve.
  • Sympathetic fibers are derived from plexus around facial artery. It contains postganglionic fibers arising in superior cervical ganglion. They pass through submandibular ganglion without relay and supply vasomotor fibers to submandibular and sublingual glands.
  • Sensory fibers reach the ganglion through the lingual nerve.
zoom view
Fig. 74: Secretomotor pathway to submandibular gland
Q.7. Write a short note on submandibular salivary gland.
(July 2016, 5 Marks) (Mar 2009, 5 Marks)
(Apr 2007, 5 Marks)
Ans. Refer to Ans 7 of the same chapter.
Q.8. Write relations and histology of submandibular gland.
(Sep 2005, 10 Marks) (Apr 2010, 7 Marks)
Ans. For relations of submandibular gland refer to Ans 6 of the same chapter.
Q.9. Describe submandibular gland with its relation and microscopic anatomy.
(Mar 2006, 10 Marks)
Ans. For description and relation refer to Ans 6 of the same chapter and for microscopic anatomy refer to Ans 16 of HISTOLOGY SECTION.
Q.10. Describe submandibular salivary gland under following heads: Position, parts, relations, secretomotor nerve and histological structure.
(Dec 2009, 15 Marks)
Ans. Position
Submandibular gland is situated in anterior part of digastric triangle and extend upto stylomandibular ligament. It is indented by the posterior border of myelohyoid which divides the gland into larger part which is superficial to the muscle and smaller part which is deep to the muscle.
 
Parts
Submandibular gland is divided into larger part which is superficial to the muscle and smaller part which is deep to the muscle, i.e. superficial part and deep part.
Superficial Part
This part fills digastric triangle. It extends upward deep to mandible upto mylohyoid line. It has inferior, lateral and medial surfaces. The gland is partially enclosed between two layers of deep cervical fascia. Superficial layer of fascia cover inferior surface of gland and is attached to the base of mandible, while the deeper layer covers medial surface of gland and is attached to mylohyoid line of mandible.
57Deep Part
It lies deep to mylohyoid, and superficial to hyoglossus and styloglossus. Posteriorly, it is continuous with superficial part round the posterior border of mylohyoid. Anteriorly it extends to posterior end of sublingual gland.
For relations refer to Ans 6 of the same chapter.
For secretomotor nerve refer to Ans 6 of the same chapter,
For histological structure refer to Ans 16 of HISTOLOGY SECTION.
Q.11. Describe submandibular gland under following headings:
(Mar 2013, 4+2+2 Marks)
a. Relations of superficial part
b. Microscopic anatomy (Diagram only)
c. Course, structure and opening of submandibular duct
Ans. For relations of superficial part refer to Ans 6 of same chapter.
For microscopic anatomy (diagram only) refer to Ans 16 of HISTOLOGY SECTION.
Course, Structure and Opening of Submandibular Duct
By its structure submandibular duct is thin walled and is 5 cm long.
In its course the submandibular duct emerges from anterior end of deep part of submandibular gland and run forward on hyoglossus in between the lingual and hypoglossal nerves. At anterior border of hyoglossus the submandibular duct is crossed by lingual nerve.
The opening of submandibular duct is on the floor of mouth on summit of sublingual papilla at the side of frenulum of tongue.
zoom view
Fig. 75: Opening of submandibular duct at floor of mouth
Q.12. Write short note on deep part of submandibular gland.
(Feb 2014, 3 Marks)
Ans. For deep part of submandibular gland refer to Ans 6 of same chapter.
Q.13. Write in tabular form, the origin, insertion, nerve supply and actions of following muscles:
(May 2017, 10 Marks)
a. Genioglossus
b. Mylohyoid
c. Buccinator
d. Sternomastoid
Ans. See following table.
Name of muscle
Origin
Insertion
Nerve supply
Action
Genioglossus
Upper genial tubercle of mandible
  • Upper fibers in tip of tongue
  • Middle fibers into dorsum
  • Lower fibers in thyoid bone
It is supplied by hypoglossal nerve
It pulls up the root of tongue, approximate palatoglossal arches and closes the oropharyngeal isthumus.
Mylohyoid
Mylohyoid line of mandible
  • Posterior fibers: Body of hyoid bone
  • Middle and anterior fibers; median raphae, between mandible and hyoid bone
Nerve to mylohyoid
  • Pulls hyoid bone upwards and backward
  • With other hyoid muscles, it fixes hyoid bone
Buccinator
  • Upper fibers: From maxilla opposite to molar teeth
  • Lower fibers: From mandible opposite to molar teeth
  • Middle fibers: From pterygomandibular raphe
  • Upper fibers: Straight to upper lip
  • Lower fibers: Straight to lower lip
  • Middle fibers: Middle fibers decussate
Lower buccal branches of facial nerve
  • Puffing of the mouth and blowing
  • Flattens cheek against gums and teeth
  • Prevents accumulation of food inside the vestibule
58
Sternomastoid
It takes origin from two heads:
  1. Sternal head: It takes origin from upper and lateral part of manubrium sterni.
  2. Clavicular head: It takes origin from medial 1/3 of superior aspect of clavicle. It passes vertically upward deep to the sternal head with which it unites to form a fusion belly
The muscle is inserted on:
  • By a thick tendon into lateral surface of mastoid process, from its tip to superior border
  • By thin aponeurosis into lateral half of superior nuchal line of occipital bone
  • Motor supply is by the spinal accessory nerve
  • Branches from ventral rami of C2 are proprioceptive
When one muscle contracts:
  • It turn the chin to opposite side
  • It can also tilt the head towards the shoulder of same side.
When both the muscles contract:
  • They draw head forward, as in eating and lifting the head from pillow
  • With longus colli they flex the neck against resistance
  • It also gives help in forced respiration.
Q.14. Name the nerves supplying digastrics muscles.
(Aug 2018, 1 Mark)
Ans. Anterior belly of the digastric muscle is innervated by the mylohyoid branch of the trigeminal nerve.
The posterior belly of the digastric muscle is innervated by the facial nerve.
 
9. STRUCTURES IN THE NECK
Q.1. Describe anatomy of thyroid gland.
(Sep 2009, 15 Marks)
Or
Describe thyroid gland with applied aspect.
(Nov 2009, 10 Mraks)
Or
Describe the thyroid gland and give its development.
(Sep 2013, 10 Marks)
Or
Describe thyroid gland under following headings:
(Feb 2016, 10 Marks)
a. Location and extent
b. External features
c. Relations
d. Blood supply
e. Applied anatomy.
Or
Describe thyroid gland with its applied anatomy.
(Feb 2013, 15 Marks)
Or
Describe the thyroid gland under following heads:
(Apr 2015, 4+2+2 Marks)
a. Size, shape and relations
b. Arterial supply and venous drainage
c. Clinical anatomy
Or
Describe the thyroid gland under the following headings:
(March 2007, 8 Marks)
a. Relations and blood supply
(3 Marks)
b. Histology
(2 Marks)
c. Development
(1½ Marks)
d. Applied anatomy
(1½ Marks)
Or
Write short note on blood supply of thyroid gland.
(May 2017, 3 Marks) (March 2007, 3 Marks)
Or
Write short note on thyroid gland and importance of blood supply.
(Apr 2007, 5 Marks)
Or
Describe thyroid gland under following headings:
(Dec 2010, 4 + 2 + 2 Marks)
a. Relations
b. Histology
c. Development
Ans. Thyroid is an endocrine gland situated in the lower part of the front and sides of neck.
 
Size of Thyroid Gland
Each lobe of thyroid measures about 5 cm × 2.5 cm × 2.5 cm and the isthmus is 1.2 cm × 1.2 cm
 
Shape of Thyroid Gland
Thyroid is a butterfly shape gland.
 
Situation or Location and Extent
  • The gland lies against vertebrae C5, C6, C7 and T1 embracing upper part of trachea.
  • Each lobe extends from middle of thyroid cartilage to fourth or fifth tracheal ring.
  • Isthmus extends from second to fourth tracheal ring.
 
59External Features
  • The gland consists of right and left lobes that are joined to each other by isthmus. Sometimes a third small pyramidal lobe may project upwards from isthmus usually to left of midline.
  • Not frequently it is connected to body of hyoid bone by fibrous or fibromuscular band known as levator glandulae thyroideae.
  • Each lateral lobe of the gland extend upward to oblique line of thyroid cartilage and below upto 5th or 6th tracheal ring.
  • Isthumus extend across midline in front of 2nd, 3rd and 4th tracheal rings.
 
Capsules of Thyroid
  1. True capsule is the peripheral condensation of the connective tissue of the gland. A dense capillary plexus is present deep to the true capsule.
  2. False capsule is derived from the pretracheal layer of deep cervical fascia. It is thin along the posterior border of lobes, but thick on inner surface of gland where it forms a suspensory ligament (of Berry) which connects the lobe to cricoid cartilage.
 
Relations
The Lobes
They are conical in shape and consists of:
An Apex
The apex is directed upwards and slightly laterally.
A Base
The base is on level with 9th or 5th tracheal ring.
Surfaces
  1. The lateral or superficial surface: It is convex and covered by sternothyroid, sternohyoid, the superior belly of omohyoid and anterior border of sternomastoid.
  2. The medial surface: It is related to:
    1. Two tubes: Trachea and esophagus
    2. Two muscles: Inferior constrictor and cricothyroid.
    3. Two nerves: External laryngeal and recurrent laryngeal
  3. The posterolateral surface: It is related to carotid sheath and overlaps common carotid artery.
Border
  1. The anterior border: It is thin and is related to anterior branch of superior thyroid artery and seperate medial and posterior surfaces.
  2. The posterior border: It is thick and rounded and separate medial and posterior surfaces. It is related to inferior thyroid artery, anastomosis between posterior branch of superior and ascending branch of inferior thyroid arteries, the parathyroid glands and thoracic duct only on left side.
The Isthmus
It connects the lower parts of two lobes. It consists of the following parts:
Surfaces
  1. The anterior surface: It is covered by right and left sternohyoid and sternothyroid, anterior jugular veins, fascia and skin.
  2. The posterior surface: It is related to 2nd to 4th tracheal ring.
Borders
  1. The upper border: This is related to anastomosis between the right and left superior thyroid arteries.
  2. The lower border: Inferior thyroid veins leave the gland at this border.
zoom view
Fig. 76: Thyroid gland with its relations
 
Blood Supply
Arterial Supply
  • Superior thyroid artery is the first anterior branch of external carotid artery. It runs downward and forward in an intimate relation with external laryngeal nerve. At pretracheal lobe it is divided into anterior and posterior branches. After providing branches to adjacent structures, it pierces pretracheal fascia to reach upper pole of lobe where nerve deviates medially. At upper pole artery divides into anterior and posterior branches.
  • Anterior branch descends into anterior border of the lobe and is continues with the upper border of isthmus to anastomose with its fellow of opposite side while the posterior branch descends on posterior border of lobe and anastomose with ascending branch of inferior thyroid artery.
  • Inferior thyroid artery is the branch of thyrocervical trunk. It runs upwards then medially and finally downwards to lower pole of gland. Its terminal part is intimately related to recurrent laryngeal nerve, while proximal part is away from the nerve The artery divides into four or five glandular branches which pierce fascia separately to reach lower part of gland. One ascending branch anastomose with posterior branch of superior thyroid artery and supply parathyroid gland.
  • 60Sometime thyroid is supplied by lowest thyroid artery which arises from bracheocephalic trunk or directly from arch of aorta.
  • Accessory thyroid arteries arising from tracheal and esophageal arteries also supplies thyroid gland.
zoom view
Fig. 77: Arterial supply of thyroid
Venous Drainage
Thyroid is drained by:
  1. Superior thyroid vein: It emerges at upper pole and accompanies superior thyroid artery. It ends in internal jugular vein.
  2. Middle thyroid vein: It emerges at middle of lobe and enters internal jugular vein.
  3. Inferior thyroid vein: It emerge at lower border of isthmus. They form plexus in front of trachea and drain into left brachiocephalic vein.
zoom view
Fig. 78: Venous drainage of thyroid
 
Lymphatic Drainage
  • Lymph from the upper part of the gland reaches the upper deep cervical lymph nodes either directly or via prelaryngeal lymph nodes.
  • Lymph from the lower part of the gland drains to lower deep cervical lymph nodes directly and also through pretracheal and paratracheal nodes.
 
Nerve Supply
Nerves are derived mainly from middle cervical ganglion and partly from superior and inferior cervical ganglion. These are vasoconstrictor.
 
Applied Anatomy or Clinical Anatomy
  • Any enlargement of thyroid gland is known as goiter.
  • Removal of thyroid is necessary in hyperthyroidism or thyrotoxicosis.
  • Hypothyroidism causes cretinism in infants and myxoedema in adults.
  • During subtotal thyroidectomy posterior part of both the lobes are left behind. This prevents the risk of removal of parathyroid gland and postoperative myxedema.
  • During thyroidectomy, superior thyroid artery is ligated near to gland for saving external laryngeal nerve. Inferior thyroid gland is ligated away from gland to save recurrent laryngeal nerve.
  • Benign tumors of gland may displace or compress neighboring structures like carotid sheath, trachea, etc.
  • Malignant tumors invade and erode neighboring structures. Nerve involvement and pressure symptoms are common in carcinoma of glands which leads to dysphagia, dyspnea and dysphonia.
 
Development
Thyroid develops from median endodermal thyroid diverticulum which grows down in front of neck from floor of primitive pharynx, just caudal to tuberculum impar during third week of intrauterine life.
Lower end of diverticulum get enlarged to form the gland. Rest of the diverticulum remains narrow and is called as thyroglossal duct. The duct grows downward across the tongue, then descend in front of the neck. In neck it passes in front of hyoid bone, binds around its lower border to become retrohyoid and finally descends below hyoid with slight inclination to one side mainly to left to reach its definitive position where its tip bifurcates and proliferation to form bilateral terminal swellings, which expand to form thyroid gland. A portion of duct near its tip sometimes forms pyramidal lobe and the remaining duct disappears.
Site of origin of thyroglossal duct is marked by foramen cecum of tongue in adults. Thyroid is earliest glandular tissue to develop and get functional during third month of development.
 
Histology
Thyroid gland has two types of secretory cells, i.e. follicular and parafollicular cells.
  1. Follicular cells: These cells line the follicle of gland and secrete tri-iodothyronin and tetraiodothyronin. During active phase, lining of follicles is columnar, while in resting phase it is cuboidal. Follicles have colloid in their lumina.61
zoom view
Fig. 79: Histology of thyroid gland (H&E stain)
Q.2. Write a short note on tributaries of internal jugular vein.
(Sep 2004, 5 Marks)
Or
Write a short note on Internal jugular vein.
(Aug 2016, 3 Marks) (Mar 2009, 5 Marks)
Ans. It is a direct continuation of sigmoid sinus. It begins at the jugular foramen and ends behind the sternal end of clavicle by joining the subclavian vein to form the bracheocephalic vein.
The origin is marked by a dilation, the superior bulb which lies in jugular fossa of temporal bone. The termination of the vein is marked by inferior bulb which lies beneath supraclavicular fossae.
 
Relations
  1. Superficially: Sternomastoid, posterior belly of digastric, superior belly of omohyoid, parotid gland, styloid process, internal carotid artery and glossopharyngeal, vagus, accessory and hypoglossal cranial nerves.
  2. Posteriorly:
    1. Transverse process of Atlas
    2. Scalenus anterior
    3. Cervical plexus
    4. First part of subclavian artery.
  3. Medially: Internal carotid artery, common carotid artery, and vagus nerve.
 
Tributaries
The tributaries of internal jugular vein are:
  1. Inferior petrosal sinus
  2. Common facial vein
  3. Lingual vein
  4. Pharyngeal vein
  5. Superior thyroid vein
  6. Middle thyroid vein
  7. Occipital vein.
zoom view
Fig. 80: Tributaries of internal jugular vein
  • The thoracic duct opens into the angle of union between left internal jugular vein and left subclavian vein.
  • In the middle of the neck the internal jugular vein may communicate with the external jugular vein via oblique jugular vein which run across anterior border of sternocleidomastoid.
 
Applied Anatomy
  • Deep to lesser supraclavicular fossa, internal jugular vein is very easily accessible for recording venous pulse tracings. Vein can be cannulated by direct puncture in interval between sternal and clavicular head of sternocleidomastoid muscle.
  • During congestive cardiac failure or any other disease where the venous pressure is raised, internal jugular vein is markedly dilated and engorged.
62Q.3. Briefly describe cervical part of sympathetic chain.
(Mar 1998, 6 Marks)
Ans. Cervical part of sympathetic chain, one on either side of cervical part of vertebral column lies in front of transverse processes of cervical of cervical vertebrae and neck of first rib behind carotid sheath and in front of prevertebral fascia.
Each trunk is continuous upwards into the cranial cavity as the internal carotid nerve accompanying the internal carotid artery. Inferiorly, it becomes continuous with the thoracic part of the sympathetic chain at the neck of the lst rib.
The cervical part of sympathetic trunk does not receive the preganglionic fibers through white rami communicates from the cervical segments of the spinal cord, but it does give gray rami communicantes to all the cervical spinal nerves. Each trunk receives preganglionic fibers from lateral horn cells of T1 to T4 spinal segments.
Theoretically, there should be eight sympathetic ganglia corresponding to 8 cervical nerves, but due to fusion there are three ganglia; superior, middle and inferior.
 
Superior Cervical Ganglion
This is largest of the three ganglia. It is spindle shaped and about 1 inch long. It lies just below the skull, opposite to the second and third cervical vertebrae. It is formed by fusion of upper four cervical ganglion.
Communications: With the 9th, 10th and 12th cranial nerves and with external and recurrent laryngeal nerves.
 
Middle Cervical Ganglion
  • The ganglion is very small. It may be divided into two or three smaller parts.
  • It lies in the lower part of neck, in front of C6 just above the inferior thyroid artery behind carotid sheath.
  • It is formed by fusion of 5th and 6th cervical ganglia. It is connected with inferior cervical ganglion directly and also through a loop that winds round the subclavian artery. This loop is known as ansa subclavia.
 
Inferior Cervical Ganglion
It is formed by fusion of 7th and 8th cervical ganglia.
  • This is often with the first thoracic ganglion and then is known as cervicothoracic ganglion or stellate ganglion.
  • It is situated between the transverse process of C7 vertebrae and the neck of first rib. It lies behind the vertbral artery and in front of ramus of spinal nerve C8. A cervicothoracic ganglion extend in front of neck of first rib.
 
Branches of Superior Cervical Ganglion
  1. Gray rami communication pass to ventral rami of upper 4 cervical nerves.
  2. The internal carotid nerve arises from the upper end of ganglion.
  3. The external carotid branches forms a plexus around external carotid artery.
  4. Pharyngeal branches take part in the formation of pharyngeal plexus.
  5. Left superior cervical cardiac branch goes to the superficial cardiac plexus with right branch goes to deep cardiac plexus.
 
Branches of Middle Cervical Ganglion
  1. Gray rami communication are given to ventral rami of 5th and 6th cervical nerves.
  2. Thyroid branches accompany inferior thyroid artery to thyroid gland. They also supply parathyroid gland.
  3. Tracheal and esopharyngeal branches.
  4. Middle cervical cardiac branches is the largest of sympathetic cardiac branches. It goes deep to cardiac plexus.
zoom view
Fig. 81: Cervical-sympathetic trunk
 
Branches of Inferior Cervical Ganglion
  1. Gray rami communicates are given to ventral rami of C7 and C8 nerves.
  2. Vertebral branches form a plexus around vertebral artery.
  3. Subclavian branches form a plexus around subclavian artery. This plexus is joined by branches from ansa subclavia.
  4. An inferior cervical cardiac branches goes to deep cardiac plexus.
Q.4. Write a short note on Horner's syndrome.
(Apr 2003, 5 Marks) (Feb 2005, 5 Marks)
(Jan 2018, 5 Marks) (Apr 2010, 5 Marks)
Or
Briefly describe Horner's syndrome.
(Apr 2007, 5 Marks)
Ans. Injury to cervical sympathetic trunk produces Horner's syndrome. It is characterized by:
  1. Ptosis, i.e. drooping of upper eyelid
  2. Miosis, i.e. constriction of pupil
  3. 63Anhydrosis, i.e. loss of sweating on that side of face.
  4. Anophthalmos, i.e. retraction of eyeball
  5. Loss of ciliospinal reflex, i.e. pinching the skin on nape of neck does not produce dilatation of pupil.
Horner's syndrome can also be caused by a lesion within the CNS anywhere at or above the first thoracic segment of spinal cord involving sympathetic fibers.
Q.5. Write in brief on cervical lymph node.
(Apr 2010, 5 Marks)
Ans.
 
Peripheral Lymph Nodes
Peripheral lymph nodes are arranged in inner and outer circles
  • Outer circle: This is formed by lymph node groups which form pericervical or cervical collar at junction of head and neck and extends from chin in front to occiput behind. They include submental, submandibular, superficial parotid, massater and occipital nodes. Outlying extensions of lymph node groups of pericervical collar:
    • Facial nodes: These are extensions of submandibular nodes and include:
      • A small buccal node lying on the lateral surface of the buccinator along the facial vein.
      • A small mandibular node which is frequently present where facial vessels cross the lower border of the mandible.
      • A small infraorbital node lying just below the orbit.
    • Superficial cervical nodes: They are situated superficial to sternomastoid (upper part) along the external jugular vein. These are the extensions of parotid nodes.
    • Anterior cervical nodes: They are situated along the anterior jugular vein. One member of this group frequently lies in the suprasternal space (suprasternal node). They are extensions of submental lymph nodes.
  • Inner circle: The inner circle is formed by following lymph node groups which lie deep to the investing layer of deep cervical fascia:
    • Infrahyoid nodes: These lie in front of thyrohyoid membrane.
    • Prelaryngeal nodes: These are situated in front of the conus elasticus or cricothyroid membrane.
    • Pretracheal lymph nodes: These lie in front of trachea below the isthmus of thyroid gland.
 
Deep Cervical Lymph Nodes
These lymph nodes lie along and around internal jugular vein, some of them inside the carotid sheath and some on the surface of sheath under cover of sternocleidomastoid.
These deep cervical lymph nodes are divided into upper and lower groups.
  • Superior or upper group of deep cervical lymph nodes: They lie above omohyoid muscle. One lymph node of this group is situated below the posterior belly of digastric between angle of the mandible and anterior border of the sternocleidomastoid in the triangle formed by posterior belly of digastric, facial vein, and internal jugular vein. It is known as jugulodigastric node. It drains the lymph primarily from the palatine tonsil.
  • Lower group of deep cervical lymph nodes: One of the lymph nodes of this group lies above the intermediate tendon of omohyoid posterior to the internal jugular vein. It is known as jugulo-omohyoid lymph node. Since this lymph node drains lymph primarily from the tongue, it is termed lymph node of the tongue. This node lies deep to sternocleidomastoid, and therefore, can be palpated only if enlarged considerably.
    Some nodes of this group extend into the supraclavicular fossa and are related to brachial plexus and subclavian vessels. These are termed supraclavicular lymph nodes (Virchow's lymph nodes). The left supraclavicular lymph nodes are clinically important because they are common site of metastasis from malignant disease (cancer) of the stomach.
zoom view
Fig. 82: Lymph nodes
Q.6. Write short note on styloid process.
(May 2017, 3 Marks)
Ans. Styloid process with the structures attached to it is known as styloid apparatus.
  • Structures attached to the process are stylohyoid, styloglossus and stylopharyngeous muscles and stylohyoid and submandibular ligaments. The five attachments resemble the reins of a chariot
  • Styloid process is a long, slender and pointed long process projecting downwards, forwards and slightly medially from temporal lobe. It descends between the external and internal carotid arteries to reach the side of pharynx. It is interposed between the parotid gland laterally and internal jugular vein medially.
  • From anterior surface of styloid process the styloglossus muscle arises and is inserted inside of tongue.64
zoom view
Fig. 83: Superior view of styloid process
  • From medial surface of base of styloid process stylopharyngeus muscle arises and is inserted on posterior border of lamina of thyroid cartilage.
  • Stylohyoid muscle extends between posterior surface of styloid process and hyoid bone.
  • Stylomandibular ligament attached laterally to styloid process above and angle of mandible below.
  • Stylohyoid ligament extend from tip of styloid process to lesser cornua of hyoid bone.
 
Features
  • External carotid artery crosses tip of styloid process superficially.
  • Facial nerve crosses at base of styloid process laterally after it emerges from stylomastoid foramen.
Q.7. Write a short note on innervation of muscles attached to styloid process.
(Mar 2006, 5 Marks)
Ans. The muscles attach to styloid process are:
  1. Styloglossus
  2. Stylohyoid
  3. Stylopharyngeus.
Innervation of:
  1. Styloglossus—it is supplied by hypoglossal nerve.
  2. Stylohyoid—it is supplied by facial nerve
  3. Stylopharyngeus—it is supplied by glossopharyngeal nerve by pharyngeal plexus.
Q.8. Enumerate the lesions lie in the midline of neck. (Do not describe).
(Feb 2013, 2 Marks)
Ans. Following are the lesions which lie in the midline of neck:
  • Ludwig's angina
  • Enlarged submental lymph node
  • Sublingual dermoid cyst
  • Thyroglossal cyst
  • Subhyoid bursitis
  • Goiter of thyroid, isthmus and pyramidal lobe
  • Enlarged lymph node and lipoma in substernal space of burns
  • Retrosternal goiter
  • Thymic swelling
  • Bony swelling arising from the manubrium sterni.
Q.9. Describe glossopharyngeal nerve under following heads: Surface attachment on brainstem, course, relations, branches and distribution, nuclei.
(Dec 2009, 15 Marks)
Or
Write in short on glossopharyngeal nerve.
(Aug 2011, 5 Marks)
Or
Write briefly on glossopharyngeal nerve.
(Apr 2008, 5 Marks)
Ans. Surface Attachment on Brainstem
  • Special visceral efferent fibers arise in nucleus ambiguous and supply stylopharyngeous muscle.
  • General visceral efferent fibers arise in inferior salivatory nucleus and travel to otic ganglion. Postganglionic fibers arise in ganglion to supply parotid gland.
  • General visceral afferent fibers are peripheral processes of cells in inferior ganglion of nerve. They carry general sensation from pharynx, palate, posterior one-third of the tongue, tonsil, carotid body and carotid sinus to ganglion. The central processes carry the sensations of these fibers to lower part of nucleus of solitary tract.
  • Special visceral afferent fibers are peripheral processes of cells in inferior ganglion. They carry sensation of taste from posterior one-third of the tongue including circumvallate papillae to inferior ganglion. The central processes carry the sensations of these fibers to nucleus of solitary tract.
  • General somatic afferent fibers are the peripheral processes of the cells in inferior ganglion of the nerve. These carry general sensations from the middle ear, proprioceptive fibers from stylopharyngeous. The central processes carry the sensations of these fibers to spinal tract of trigeminal nerve.
zoom view
Fig. 84: Superior attachment on brainstem and nuclei of glossopharyngeal nerve
65
zoom view
Fig. 85: Course and distribution of glossopharyngeal nerve
 
Course and Relations
  • In its intraneural course fibers of glossopharyngeal nerve pass forward and laterally in between the olivary nucleus and inferior cerebellar peduncle via reticular formation of medulla.
  • At base of brain nerve is attached by three to four filaments at upper part of posterolateral sulcus of medulla just above roots of vagus nerve.
  • In its intracranial course filaments get united and constitute a trunk which passes forward and lateral to jugular foramen by crossing and grooving jugular tubercle of occipital bone.
  • Glossopharyngeal nerve leaves the skull via middle part of juglar foramen anterior to vagus and accessory nerves.
  • In jugular foramen nerve lies in a deep groove and leads to cochlear canaliculus and separated from both vagus and accessory spinal nerve by inferior peterosal sinus.
Extracranial Course
  • In its extracranial course the nerve descend in between internal jugular vein and internal carotid artery deep to styloid process and muscles attached to it. It turn forward and wind at lateral aspect of stylopharyngeous and pass between external and internal carotid arteries and reaches to side of pharynx. Here it gives off pharyngeal branches and enters sub-mandibular region by passing deep to hyoglossus where it split into tonsilar and lingual branches.
  • At base of skull glossopharyngeal nerve presents superior as well as inferior ganglion. Superior ganglion does not give off any of the branches while inferior ganglion occupies notch on lower border of petrous temporal and gives communicating and tympanic branches.
 
Branches and Distribution
  • Tympanic nerve: It is the branch of inferior ganglion of glossopharyngeal nerve. The nerve enters middle ear via tympanic canaliculus which forms tympanic plexus and distribute its fibers to middle ear, auditory tube, mastoid antrum and air cells. One branch of plexus is called as lesser petrosal nerve and it consists of preganglionic secretomotor fibers for parotid gland and relay in otic ganglion. Postganglionic fibers join auriculotemporal nerve to reach the gland.
  • Carotid branch: It descends over internal carotid artery and supplies to carotid sinus and carotid body.
  • Pharyngeal branches: They take part in the formation of pharyngeal plexus with vagal and sympathetic fibers. Glossopharyngeal fibers are distributed to mucous membrane of pharynx.
  • Muscular branch: It supplies to stylopharyngeus.
  • Tonsillar branch: It supplies to tonsil and join lesser palatine nerves to form a plexus from which fibers are distributed to soft palate and palatoglossal arches.
  • Lingual branches: They carry taste and general sensations from posterior one third of tongue including circumvallate papillae.
 
Nuclei
There are three nuclei in upper part of medulla which are:
  1. Nucleus ambiguous: It is branchiomotor
  2. Inferior salivatory nucleus: It is parasympathetic
  3. Nucleus of tractus solitarius: It is gustatory.
Q.10. Write short note on lymphatic drainage of oral cavity.
(Aug 2011, 5 Marks)
Ans. Lymphatic drainage of the oral cavity is divided firstly into regional nodes and then into deep cervical nodes.
  • Parotid nodes lie upon the parotid gland and drain it
  • Buccal nodes lie on the cheek over the buccinator muscle and siphon off the lymph that is collecting in the submandibular nodes
  • Submandibular nodes lie on the lateral wall of the submandibular gland and drain the cheek, the upper lip, lower lip, maxillary sinus, upper and lower teeth, anterior two-third of the tongue, floor of the mouth, vestibule and gums
  • Submental nodes are found in the submental triangle below the chin and drain the tip of the tongue, the floor of the anterior part of the mouth, the incisors, the central part of the lower lip and the skin of the chin
  • Superficial cervical nodes lie on the external jugular vein and drain the skin over the angle of the jaw and 66the skin covering the lower portion of the parotid gland.
Deep cervical nodes are as follows:
  • Jugulodigastric node sits posteroinferiorly to the jaw and drains the tonsils and the tongue.
  • Jugulo-omohyoid node is found close to the omohyoid muscle and drains the tongue.
Q.11. Describe hypoglossal nerve under following heads:
(Feb 2014, 3+3+2 Marks)
a. Course
b. Branches
c. Applied anatomy
Ans. Course
Intraneural course: Fibers pass forwards lateral to the medial longitudinal bundle, medial lemniscus and pyramidal tract, and medial to the reticular formation and olivary nucleus. Hypoglossal nerve is attached to the anterolateral sulcus of medulla in between the pyramid and the olive, by 10 to 15 rootlets. These rootlets run laterally behind the vertebral artery, and they join to form two bundles which pierce the duramater separately near hypoglossal canal. The nerve leaves the skull via hypoglossal canal.
Extracranial Course: Hypoglossal nerve first lies deep to the internal jugular vein and inclines between the internal jugular vein and internal carotid artery. It crosses the vagus and reaches in front of it.
The nerve descends between the internal jugular vein and internal carotid artery in front of vagus deep to the parotid gland, styloid process, posterior belly of the digastric. At the lower border of the posterior belly of the digastric, it curves forwards, crosses the internal and external carotid arteries and the loop of the lingual artery. The nerve then passes deep to posterior belly of the digastric to enter the submandibular region.
The nerve then continues forwards on the hyoglossus and genioglossus, deep to the submandibular gland and the mylohyoid muscle and enters the substance of the tongue to supply all its intrinsic muscles and most of its extrinsic muscles.
zoom view
Fig. 86: Course of hypoglossal nerve
 
Branches
Branches containing fibers of the hypoglossal nerve proper:
These branches supply extrinsic and intrinsic muscles of the tongue. Only extrinsic muscle, the palatoglossus is supplied by fibers of the cranial accessory nerve through the vagus and pharyngeal plexus.
Branches of the hypoglossal nerve containing fibers of nerve C1:
These fibers join the nerve at the base of the skull.
  1. Meningeal branch contains sensory and sympathetic fibers.
  2. Descending branch continues as upper root of the ansa cervicalis or descendens hypoglossi.
  3. Branches to thyrohyoid and geniohyoid muscles.
 
Applied Anatomy
  • Hypoglossal nerve is tested clinically by asking the patient to protrude his/her tongue. In normal people the tongue is protruded straight forward but if the nerve is paralysed, tongue deviates to paralyzed side.
  • 67An infranuclear lesion of the hypoglossal nerve leads to paralysis of tongue on that side. Gradual atrophy of the paralysed half of the tongue occurs and tongue looks shrunken.
  • Supranuclear lesions of the hypoglossal nerve lead to paralysis without wasting. On protrusion, the tongue deviates to opposite side.
Q.12. Answer in brief on effect of unilateral damage to hypoglossal nerve.
(May 2017, 3 Marks)
Ans. Due to unilateral damage there is lower motor neuron type of paralysis of muscles on the tongue over that side. On asking the patient to protrude his/her tongue, tip of the tongue deviates to paralysed side because of unopposed action of the muscles of healthy side.
On clinical testing of hypoglossal nerve, if there is unilateral damage to hypoglossal nerve, the tongue deviates to the side of the lesion or paralysis.
Q.13. Name the blood vessels supplying thyroid gland.
(Aug 2016, 2 Marks)
Ans. Following are the blood vessels supplying thyroid gland:
  • Superior thyroid artery
  • Inferior thyroid artery
  • Lowest thyroid artery or thyroidea ima artery
  • Accessory thyroid artery.
Q.14. Name the structures attached to styloid process.
(Aug 2018, 1 Mark)
Ans. Structures attached to the process are:
  • Stylohyoid
  • Styloglossus
  • Stylopharyngeous muscles
  • Stylohyoid and submandibular ligaments.
The five attachments resemble the reins of a chariot.
Q.15. Write very short answer on thyrocervical trunk.
(Aug 2018, 2 Marks)
Ans. It is the short, wide branch of the subclavian artery.
 
Origin, Course, and Termination
The thyrocervical trunk arises from the upper aspect of the first part of the subclavian artery at the medial margin of the scalenus anterior and lateral to the origin of vertebral artery. It immediately terminates into three branches.
Branches
These are:
  • Inferior thyroid artery.
  • Superficial cervical artery.
  • Suprascapular artery.
 
10. THE PREVERTEBRAL AND PARAVERTEBRAL REGION
Q.1. Write a short note on atlantoaxial joint.
(Sep 2002, 3 Marks)
(Mar 2009, 5 Marks)
Ans. It is a well separated joint which is formed between atlas and axis.
 
Types and Articular Surfaces
  • There are two lateral atlantoaxial joints between inferior facets of atlas and superior facets of axis. They are the plane joints.
  • One median atlantoaxial joint between the dens, i.e. odontoid process and the anterior arch and between dens and transverse ligament of the atlas. This is a pivot joint. It consists of two separate synovial cavities, anterior and posterior.
 
Ligaments
  • Lateral atlantoaxial joint is supported by:
    • Capsular ligament all around.
    • Lateral part of the anterior longitudinal ligament.
    • Ligamentum flavum.
  • Median atlantoaxial joint is strengthened by following, i.e.
    • Anterior smaller part of the joint between anterior arch of atlas and dens is surrounded by a loose capsular ligament.
    • Posterior larger part of the joint between dens and transverse ligament is often continuous with one of the atlanto-occipital joints. Here main support is transverse ligament which forms a part of the cruciform ligament of atlas.
 
Transverse Ligament
It is attached over each side to medial surface of lateral mass of atlas. In median plane, its fibers are prolonged upwards to basiocciput and downwards to body of axis, thus forming cruciform ligament of atlas vertebra. Transverse ligament embraces the narrow neck of the dens, and prevents its dislocation.
 
Ligaments Connecting Axis with Occipital Bone
Ligaments which connect axis with occipital bone are the membrana tectoria, cruciate ligament, apical ligament of the dens and the alar ligaments.
  • Membrana tectoria: It is an upward continuation of posterior longitudinal ligament. It lies posterior to transverse ligament. Membrana tectoria is attached inferiorly to posterior surface of the body of axis and superiorly to the basiocciput.
  • Cruciate ligament: Transverse ligament is attached over each side to medial surface of lateral mass of atlas. In median plane, its fibers are prolonged upwards to basiocciput and downwards to body of axis, thus forming cruciform ligament of atlas vertebra.
  • Apical ligament of dens: It extends from apex of dens close to anterior margin of foramen magnum behind the attachment of cruciate ligament. Mainly it is the continuation of the notochord.
  • Alar ligament, one on each side, extends from upper part of lateral surface of dens to medial surface of occipital condyles. They are strong ligaments which limit both the rotation as well as flexion of head. They get relaxed during extension.
 
68Movements of Atlantoaxial Joints
  • All the three joints produce movements which are rotatory and take place at around a vertical axis.
  • Dens forms a pivot around which atlas rotates. This movement is limited by the alar ligaments.
  • Rotatory movements are brought about by obliquus capitis inferior, rectus capitis posterior major and the splenius capitis of one side, acting along with sternocleidomastoid of opposite side.
Q.2. Write a short note on vertebral artery.
(Apr 2010, 5 Marks)
Ans. Introduction
Vertebral artery is one of the two principal arteries which supply the brain. In addition it also supplies to spinal cord, meninges, and surrounding muscles and bones.
 
Origin and Course
It arises from the posterosuperior aspect of first part of subclavian artery near its commencement. It runs a long course and end in cranial cavity by supplying brain.
zoom view
Fig. 87: Course and parts of vertebral artery
 
Parts of Vertebral Artery
Artery is divided into four parts as follows:
  1. First part of vertebral artery: It extends from origin of artery to the transverse process of 6th cervical vertebrae. This part of artery run upward and backward in triangular space between scalenus anterio and longus colli muscles known as scalenovertebral triangle.
    Scalenovertebral triangle
    It is present at the root of neck.
    Boundaries
    • Medial: Lower oblique part of longus colli
    • Lateral: Scalenus anterior
    • Apex: Transverse process of C6 vertebrae
    • Base: First part of subclavian artery
    • Posterior wall: Transverse process of C7, ventral ramus of C8 nerve, neck of first rib and cupola pleurae
    Contents
    • First part of vertebral artery
    • Cervical part of sympathetic chain.
    zoom view
    Fig. 88: Vertebral artery with branches
    Relations
    Anteriorly: Carotid sheath with common carotid artery, vertebral vein, inferior thyroid artery and thoracic duct on left side.
    Posterior: Transverse process of C7 vertebrae, stellate ganglion and ventral rami of C7 and C8 nerves.
  2. Second part of vertebral artery: It runs through foramina transversaria of upper six cervical vertebrae. Its course is vertically upto axis vertebrae. It then run upward and laterally to reach foramen transversarium of atlas vertebrae.
    Relations:
    1. Ventral rami of nerves C2-6 lie posterior to vertebral artery.
    2. The artery is accompanied by venous plexus and by large branch from stellate ganglion.
  3. Third part of vertebral artery: This part lies in suboccipital triangle emerging from foramina transversarium of atlas, the artery winds medially round the posterior aspect of lateral mass of atlas. It runs medially lying on the posterior arch of this bone and enter vertebral canal by passing deep to lower arch margin of posterior atlanto-occipital membrane.
    Relations
    Anteriorly
    :
    Lateral mass of atlas
    Posteriorly
    :
    Semispinalis capitis
    Laterally
    :
    Rectus capitis lateralis
    Medial
    :
    Ventral ramus of 1st cervical nerve
    Inferior
    :
    Dorsal ramus of C1 nerve
    Posterior arch of atlas.
  4. Fourth part:
    • It extends from posterior atlanto-occipital membrane to lower border of pons
    • 69In vertebral canal, it pierces dura and arachnoid, and ascends in front of root of hypoglossal nerve. As it ascends, it inclines medially to reach the front of medulla. At lower border of pons, it unites with its fellow of contralateral side to form basilar artery.
    Branches of vertebral artery: First part gives off no branches.
    Cervical branches
    • Spinal branches from second part enter vertebral canal via intervertebral foramina and supply spinal cord, meninges and vertebrae.
    • Muscular branches arise from third part and supply suboccipital muscles.
    Cranial branches
    These branches originate from fourth part:
    • Meningeal branches
    • Posterior spinal
    • Anterior spinal artery
    • Posterior inferior cerebellar artery
    • Medullary arteries.
    Development of vertebral artery
    • First part: From branch of dorsal division of 7th cervical intersegmental artery
    • Second part: From postcostal anastomosis
    • Third part: From spinal branch of first cervical intersegmental artery
    • Fourth part: From preneural branch of first cervical intersegmental artery.
Q.3. Write on origin, insertion, nerve supply and action of prevertebral muscle in tabular form.
(Apr 2007, 15 Marks)
Ans. Prevertebral muscles are:
  1. Longus colli
  2. Longus capitis
  3. Rectus capitis anterior
  4. Rectus capitis lateralis.
Muscle
Origin
Insertion
Nerve supply
Action
Longus colli
It extends from atlas to T3 vertebral
  1. Upper oblique part originates from anterior tubercle of transverse process of C3, C4, C5
  2. Lower oblique part from bodies of upper T2-T3 vertebrae
  3. Middle vertical part from bodies of upper three thoracic and lower three cervical vertebrae
  1. Upper oblique part in anterior tubercle of atlas
  2. Lower oblique part in anterior tubercle of transverse process of C5 and C6 vertebrae
  3. Middle vertical part in bodies of C2, C3 and C4 vertebrae
Ventral rami of nerve C3-C8
  1. Neck flexion
  2. Oblique part flex the neck laterally
  3. Lower oblique part rotates the neck to opposite side
Longus capitis
It overlap longus colli. It is thick above and narrow below
It originates from the anterior tubercle of transverse processes of C3, C4, C5 and C6 vertebrae
It is inserted in inferior surface of basilar part of occipital bone
Ventral rami of nerves C1-C3
Head flexion
Rectus capitis anterior
It is very short as well as flat muscle. It lies deep to longus capitis
It originates from anterior surface of lateral mass of atlas in front of occipital condyle
It is inserted in basilar part of occipital bone
Ventral ramus of nerve C1
Head flexion
Rectus capitis lateralis
It is a short flat muscle
It originates from upper surface of transverse process of atlas
It is inserted in inferior surface of jugular process of occipital bone
Ventral rami of nerves C1, C2
Head flexion laterally
zoom view
Fig. 89: Prevertebral muscles
Q.4. Write a short note on movement of atlanto-occipital bone.
(Apr 2007, 4 Marks)
Ans. Superior aspect of each lateral mass shows an elongated concave facet which articulates with corresponding condyle of occipital bone to form atlanto-occipital bone.
  • Main movement is flexion with a little lateral flexion and rotation. Flexion is caused by longus capitis and rectus capitis anterior.
  • Extension is caused by recti capitis posterior major and minor, obliques capitis superior, semispinalis capitis, splenius capitis and upper part of trapezius.
  • Lateral bending is caused by rectus capitis, semispinalis capitis, splenius capitis, sternoclei-domastoid and trapezius.70
zoom view
Fig. 93: Cervical plexus
Q.5. Write short note on cervical plexus.
(Apr 2007, 5 Marks)
Ans. Cervical plexus is formed by the ventral rami of upper first four cervical spinal nerves C1, C2, C3 and C4. Rami emerge between anterior and posterior tubercles of cervical transverse processes grooving costotransverse bars. Four roots connect to each other and form three loops.
 
Position and Relations of Cervical Plexus
Cervical plexus is related:
  1. Posteriorly to muscles which originates from posterior tubercles of transverse process i.e. levator scapulae and scalenus medius.
  2. Anteriorly to prevertebral fascia, internal jugular vein and sternocleidomastoid.
 
Branches of Cervical Plexus
  1. Cutaneous branches or superficial branches: These branches provide sensory innervations to the skin. They arise at the level of middle third of sternocleidomatoid at posterior border to innervate skin of neck and scalp between auricle and external occipital protuberance. Branches and the regions innervated by them are:
    1. Anterior cutaneous nerve of neck: Arises from ventral rami of C2 and C3 and run across sternomastoid to supply skin and neck to sternum.
    2. Supraclavicular nerve: Formed by ventral rami of C3 and C4 nerves. The nerve emerges at posterior border of sternocleidomatoid muscle.
    3. Greater auricular nerve: It is the largest ascending branch of cervical plexus. It arises from ventral rami of C2 and C3 nerves. It ascends on sternomastoid muscle to reach parotid gland where it subdivides into anterior and posterior branches.
    4. Lesser occipital: It arises from ventral ramus of C2 of spinal cord. It is visible at posterior border of sternocleidomastoid muscle.
  2. Deep Branches:
    1. Communicating branches:
      1. Gray rami pass from superior cervical ganglion to roots of C1 – C4 nerves.
      2. Branch from C1 join hypoglossal nerve and carry fiber for supply of thyrohyoid and geniohyoid muscles and superior belly of omohyoid via ansa cervicalis.
      3. Branch from C2 to sternocleidomastoid and branch from C3 and C4 to trapezius communicate to accessory nerve.
    2. Muscular branches:
      1. Muscles supplied only by cervical plexus
        1. Rectus capitis anterior from C1
        2. Rectus capitis lateralis from C1, C2
        3. Longus capitis from C1 – C3
        4. Lower root of ansa cervicalis from C2, C3.
      2. Muscles supplied by cervical plexus along with brachial plexus
        1. Sternocleidomastoid from C2 with accessory nerve
        2. Trapezius by C3, C4 with accessory nerve
        3. Levator scapulae by C3, C4 with C5
        4. Phrenic nerve by C3, C4 with C5
        5. Longus colli by C3 – C8
        6. Scalenus medius by C3 – C8
        7. Scalenus anterior by C4 – C6
        8. Scalenus posterior by C6 – C8.
Q.6. Write a short note on scalenus anterior muscle.
(Sep 1999, 4 Marks)
Or
Write short note on relations of scalenus anterior muscle.
(Apr 2007, 4 Marks)
71Ans.
 
Scalenus Anterior Muscle
  • Origin: Orignates from anterior tubercles of transverse process of cervical vertebrae 3, 4, 5 and 6.
  • Insertion: Scalene tubercle and adjoining ridge on superior surface of the first rib.
  • Nerve supply: Ventral rami of nerves C4, 5 and 6.
zoom view
Fig. 91: Relation of scalenus anterior
 
Actions
  1. Anterolateral flexion of cervical spine.
  2. Rotates cervical spine to opposite side.
  3. Elevates the first rib during inspiration.
  4. Stabilizes neck along with other muscle.
 
Relations
  1. Anteriorly: Phrenic nerve covered by prevertebral fascia, lateral part of carotid sheath containing internal jugular vein, descendens cervicalis, sternomastoid and clavicle.
  2. Posteriorly: Brachial plexus, subclavian artery, cervical pleura covered by suprapleural membrane, scalenus medius.
  3. The lateral border of muscle is related to trunks of brachial plexus and subclavian artery which emerges at this border and enter posterior triangle.
Medial Border of Muscle is Related to
In its lower part to an inverted V shaped interval which is formed by the diverging borders of scalenus anterior and longus colli. This interval consists of many important structures, i.e.
  • Vertebral vessels running vertically from base to the apex of this space
  • Inferior thyroid artery arching medially at level of 6th cervical transverse process
  • Sympathetic trunk
  • First part of subclavian artery traverses lower part of gap
  • Over left side, thoracic duct arches laterally at level of 7th cervical transverse process
  • Carotid sheath covers all the structures given above
  • Sternocleidomastoid covers carotid sheath
In its upper part, scalenus anterior get separated from longus capitis by ascending cervical artery.
Q.7. Write very short answer on phrenic nerve.
(Apr 2018, 2 Marks)
Ans. Phrenic nerve is basically a mixed nerve which carries motor fibers to diaphragm and sensory fibers from diaphragm, pleura, pericardium as well as part of peritoneum.
 
Origin
It arises from ventral rami of third, fourth and fifth cervical vertebrae but chiefly from fourth cervical vertebrae.
 
Course and Relations
  • It is formed at lateral border of scalenus anterior, opposite to middle of sternocleidomastoid, at the level of upper border of thyroid cartilage.
  • It runs vertically downwards on anterior surface of scalenus anterior muscle. Since the muscle is oblique, nerve appears to cross it obliquely from its lateral towards its medial border. In this part, nerve is related anteriorly to the prevertebral fascia, the inferior belly of the omohyoid, transverse cervical artery, suprascapular artery, internal jugular vein, sternocleidomastoid and thoracic duct on left side.
  • As the nerve leave anterior surface of scalenus anterior, phrenic nerve runs downwards on cervical pleura just behind the commencement of brachiocephalic vein. Here it crosses internal thoracic artery from lateral towards the medial side, and enters the thorax behind first costal cartilage. Over left side, nerve leaves (crosses) the medial margin of scalenus anterior muscle at a higher level and crosses in front of the first part of subclavian artery.
 
Distribution
  • Phrenic nerve alone provide motor supply to diaphragm
  • It gives sensory innervations to diaphragmatic pleura, pericardium and subdiaphragmatic pleura.
Q.8. Write very short answer on intervertebral joints.
(Apr 2018, 2 Marks)
Ans. The joints of the neck include intervertebral joints between the lower 6 cervical vertebrae and craniovertebral joints.
The joints between the lower 6 cervical vertebrae are typical cervical joints. These are similar to those in the other parts of the vertebral column. They permit flexion, extension, and lateral bending but little rotation.
The joints between lst and 2nd cervical vertebrae and those between lst cervical vertebrae and skull permit rotation and nodding of head, respectively.
The joints of neck are clinically important due to high incidence of spondylosis, disc prolapse, and fracture dislocation in the cervical region.
All intervertebral joints are innervated by adjoining spinal nerves particular by their posterior divisions.
 
7211. BACK OF THE NECK
Q.1. Describe boundaries and contents of suboccipital triangle.
(April 2003, 10 Marks)
Or
Write short note on contents and boundaries of suboccipital triangle.
(Aug 2018, 5 Marks)
Ans. Boundaries of Suboccipital Triangle
Superomedially: Rectus capitis posterior major muscle supplemented by the rectus capitis posterior minor.
Superolaterally: Superior oblique capitis muscle.
Inferiorly: Inferior oblique capitis muscle.
Roof:
  1. Medially: Dense fibrous tissue covered by semispinalis capitis.
  2. Laterally: Longissimus capitis and occasionally splenius capitis
Floor: It is formed by:
  1. Posterior arch of atlas.
  2. Posterior atlanto-occipital membrane.
 
Contents of Suboccipital Triangle
  1. Third part of vertebral artery.
  2. Dorsal ramus of nerve C1-suboccipital nerve.
  3. Suboccipital plexus of veins.
zoom view
Fig. 92: Boundaries and contents of suboccipital triangle
 
Third Part of Vertebral Artery
Out of the four parts of vertebral artery only third part appears in the suboccipital triangle. This part appears at foramen transversarium of atlas vertebra. After emerging from foramen, the artery winds backward and medially behind the lateral mass of atlas; lodges in the groove on upper surface of its posterior arch, and finally leaves the triangle by passing deep to the thick lateral edge of posterior atlanto–occipital membrane to enter vertebral canal where it continues as fourth part of vertebral artery.
Vertebral artery is separated from posterior arch of atlas by first cervical nerve and its dorsal and ventral rami.
 
Dorsal Ramus of Nerve C1–Suboccipital Nerve
Dorsal ramus emerges between the posterior arch of atlas and the vertebral artery and soon breaks up into five muscular branches to supply four suboccipital nerves and semispinalis capitis. The nerve to inferior oblique gives off a communicating branch to the greater occipital nerve.
 
Suboccipital Plexus of Veins
It lies in and around the suboccipital triangle and drains to:
  • Muscular veins
  • Occipital veins
  • Internal vertebral venous plexus
  • Condylar emissary vein
  • Deep cervical vein
  • Plexus of vein around vertebral artery.
 
12. THE CRANIAL CAVITY
Q.1. Write a short note on falx cerebri.
(Sep 2001, 5 Marks)
Or
Briefly describe on falx cerebri.
(Oct 2007, 5 Marks)
Ans. This is a large sickle shaped fold of dura mater occupying medial longitudinal fissure between two hemispheres. It has two ends:
  1. Anterior end is narrow and is attached to cristae galli.
  2. Posterior end is broad and is attached along median plane to upper surface of tentorium cerebelli.
Falx cerebri consists of two margins:
  1. Upper margin is convex and is attached to lips of sagittal sulcus.
  2. Lower margin is concave and free.
73It has right and left surfaces each of which is related to medial surface of corresponding cerebral hemisphere.
Three important venous sinuses are present in relation to this fold.
  1. Superior sagittal sinus lies along upper margin.
  2. Inferior sagittal sinus lies along lower margin.
  3. Straight sinus along the line of attachment of falx to tentorium cerebelli.
zoom view
Fig. 93: Falx cerebri
Q.2. Enumerate paired and unpaired dural venous sinuses.
(Sep 2004, 5 Marks)
Ans. There are 23 venous sinuses out of which 8 are paired and 7 are unpaired.
 
Paired Venous Sinus
  1. Cavernous sinus
  2. Superior petrosal sinus
  3. Inferior petrosal sinus
  4. Transverse sinus
  5. Sigmoid sinus
  6. Sphenoparietal sinus
  7. Petrosquamous sinus
  8. Middle meningeal sinus.
In above sinuses there is one sinus on each side.
 
Unpaired Venous Sinus
They are median in position:
  1. Superior sagittal sinus
  2. Inferior sagittal sinus
  3. Straight sinus
  4. Occipital sinus
  5. Anterior intercavernous sinus
  6. Posterior intercavernous sinus
  7. Basilar plexus of veins.
Q.3. Mention situation, boundaries, contents, communication and tributaries of cavernous sinus.
(Feb 2002, 10 Marks)
Or
Describe cavernous sinus along with diagram.
(Apr 2018, 10 Marks)
Or
Describe the cavernous sinus and give its applied aspects.
(Sep 2013, 20 Marks)
Or
Write a short note on cavernous sinus.
(May 2014, 5 Marks) (Feb 2005, 5 Marks)
(Feb 2014, 3 Marks) (Dec 2010, 5 Marks)
(Apr 2007, 5 Marks)
Or
Write short note on relations of cavernous sinus.
(Aug 2018, 5 Marks)
Ans. Situation
Each cavernous sinus is a large venous space situated in a middle cranial fossa on either side of body of sphenoid bone.
Boundaries
  • Floor and medial wall: Formed by endosteal dura mater.
  • Roof and lateral wall: Formed by meningeal dura mater.
  • Anteriorly: Sinus extends to medial end of superior orbital fissure.
  • Posteriorly: To apex of petrous temporal bone.
 
Contents or Relations
  1. Structure outside the sinus:
    1. Superiorly: Optic tract, optic chiasma, olfactory tract, internal carotid artery and anterior perforated substance.
    2. Inferiorly: Foramen lacerum, junction of body and greater wing of sphenoid.
    3. Medially: Hypophysis cerebri and sphenoidal air sinus.
    4. Below laterally: Mandibular nerve.
    5. Laterally: Temporal lobe with uncus.
    6. Anteriorly: Apex of the orbit and superior orbital fissure.
    7. Posteriorly: Apex of petrosal temporal and crus cerebri of the midbrain.
  2. Structures inside lateral wall of sinus: From above to downwards
    • Oculomotor nerve: In anterior part of cavernous sinus, nerve divide in superior and inferior divisions which leave sinus by passing via superior orbital fissure.
    • Trochlear nerve: In anterior part of cavernous sinus the nerve crosses superficial to oculomotor nerve and enters orbit via superior orbital fissure.
    • Ophthalmic nerve: In anterior part of cavernous sinus, nerve divides into lacrimal, frontal and nasociliary branches.
    • Maxillary nerve: It leaves sinus by passing via foramen rotundum on its way to pterygopalatine fossa.
    • Trigeminal ganglion: Ganglion and its dural cave project inside the posterior part of lateral wall of sinus.74
    zoom view
    Fig. 94: Coronal section of cavernous sinus
    zoom view
    Fig. 95: Communications and tributaries of cavernous sinus
  3. Structure passing through medial aspect of sinus:
    1. Internal carotid artery: With venous plexus and sympa-thetic plexus around it.
    2. Abducent nerve: Infralateral to internal carotid artery.
Structurs in lateral wall and on medial aspect of sinus are seperated from blood by endothelial lining.
 
Communication
  • The cavernous sinus drains into transverse sinus through superior petrosal sinus.
  • Cavernous sinus drains into internal jugular vein through inferior petrosal sinus and through plexus around internal carotid artery.
  • Cavernous sinus drains into pterygoid plexus of veins through emissary veins.
  • Cavernous sinus drains into facial vein through superior ophthalmic vein.
  • The right and left cavernous sinus communicate with each other through anterior and posterior inter cavernous sinuses and through basilar plexus of veins.
All the above communications are valueless and blood can flow via them in either direction.
Tributaries of Cavernous Sinus:
  1. From the orbit.
    1. Superior ophthalmic vein
    2. A branch of inferior ophthalmic vein or sometimes vein itself
    3. The central vein of retina may drain either in superior opthlamic vein or in cavernous sinus.
  2. From the brain
    1. Superficial middle cerebral vein
    2. Inferior cerebral veins from temporal lobe.
  3. From the meninges
    1. Sphenoparietal sinus
    2. The frontal trunk of middle meningeal vein may drain either in pterygoid plexus via foramen ovale or in sphenoparietal or cavernous sinus.
 
Applied Anatomy
  • Thrombosis of cavernous sinus may be caused by sepsis in dangerous area of face, in nasal cavities and in paranasal air sinuses. This gives rise to:
    • Nervous symptoms:
      • Severe pain in eye and forehead in the area of distribution of ophthalmic nerve.
      • Involvement of 3rd, 4th and 6th cranial nerves resulting in paralysis of muscles supplied.
    • Venous symptoms: Marked edema of eyelid, cornea and root of nose with exophthalmos due to congestion of veins.
  • Communication between cavernous sinus and internal carotid artery may be produced by head injury. When this happens the eye wall protrudes and pulsates with each heart beat. It is also known as pulsating exopthalmos.
Q.4. Write a short note on superior sagittal sinus.
(March 2000, 5 Marks)
Ans. Superior Sagittal Sinus
The sinus occupies upper convex attached margin of falx cerebri.
zoom view
Fig. 94: Superior saggital sinus
It begins anteriorly at cristae galli by union of tiny meningeal vessels, there it communicates with veins of frontal sinus and occasionally with veins of nose. As the sinus run upwards and backwards, it becomes progressively larger in size. It is triangular in cross-section. It ends near internal occipital protuberance 75by turning to one side mainly the right and become contineous with right transverse sinus. It communicates with opposite sinus. The junction of all these sinuses is known as “confluence of sinuses”.
 
Tributaries
  1. Superior cerebral veins which never open in venous lacunae
  2. Parietal emissary veins
  3. Venous lacunae three on each side which first receives diploic and meningeal veins and then open in sinus.
  4. Occasionally a vein from nose open into the sinus when foramen cecum is patent.
 
Interior of Sinus
It shows:
  • Openings of superior cerebral veins
  • Opening of venous lacunae usually three on each side
  • Arachnoid villi and granulations which project into lacunae as well as sinus.
  • Numerous fibrous bands crossing inferior angle of sinus.
 
Applied Anatomy
Thrombosis of superior sagittal sinus may be caused by spread of infection from nose, the scalp or diploe which give rise to:
  1. Considerable rise in intracranial tension.
  2. Delirium and sometimes convulsions due to congestion of superior cerebral veins.
  3. Paraplagia of upper motor neuron type due to bilateral involvement of paracentral lobules of cerebrum where lower limbs and perineum are presented.
Q.5. Write about pituitary gland, write its applied anatomy also.
(Aug 2005, 10 Marks)
Or
Write short note on pituitary gland.
(Oct 2014, 3 Marks)
Ans. Anatomy of Pituitary Gland
Situation: The gland lies in the hypophyseal fossa. The fossa is roofed by diaphragma sellae. Stalk of hypophysis cerebri pierces diaphragma sellae and is attached above to floor of IIIrd ventricle.
zoom view
Fig. 97: Parts of hypophysis cerebri in saggital section
 
Relations
  • Superiorly: Diaphragma sellae, optic chiasma, tuber cinerium and infundibular recess of IIIrd ventricle.
  • Inferiorly: Irregular venous channels between two layers of dura mater lining the floor of hypophyseal fossa, sphenoidal air sinus and hypophyseal fossa.
  • On each side: Cavernous sinus with its contents.
 
Subdivisions
The gland has two main parts which differ morphologically, embryologically and anatomically. The two parts are:
  • Adenohypophysis:
    It consists of the following parts:
    • Anterior lobe or pars anterior, pars distalis or pars glandularis: This is the largest part of gland.
    • Intermediate lobe or pars intermedia: This is in the form of thin strip which is separated from anterior lobe by intraglandular cleft.
    • Tuberal lobe or pars tuberalis: It is an upward extension of anterior lobe that surrounds and forms the part of infundibulum.
  • Neurohypophysis:
    • Posterior lobe: It is smaller than anterior lobe and lies in the posterior concavity of larger anterior lobe.
    • Infundibular stem: It contains neural connections of posterior lobe with hypothalamus.
    • Median eminence of tuber cinereum which is continuous with infundibular stem.
zoom view
Fig. 98: Arterial supply of pituitary gland
 
Blood Supply
Arterial Supply
  • The hypophysis cerebri is supplied by the following branches of internal carotid artery:
    • 76Superior hypophyseal artery on each side.
    • Inferior hypophyseal artery.
  • Each superior hypophyseal artery supplies to the ventral part of hypothalamus, upper part of infundibulum, lower part of infundibulum via separate descending branch known as trabecular artery.
  • Each inferior hypophyseal artery divides into medial and lateral parts which join to form arterial ring, the branches from ring supply to posterior lobe.
  • Anterior lobe is supplied by portal vessels arising from the capillary tufts which is formed by superficial hypophyseal arteries. Long portal vessels drain median eminence and upper infundibulum while the short portal veins drain lower infundibulum.
 
Venous Drainage
Short veins emerge on surface gland and drain into neighbouring venous sinuses. Hormones pass out of gland via venous blood and carried to their target cells.
 
Applied Anatomy
Pituitary tumors give rise to two main categories of symptoms:
  1. General Symptoms: These are caused due to pressure over surrounding structures. The symptoms are:
    • Sella turcica is enlarged in size.
    • Pressure over optic chiasma causes bitemporal hemianopia.
    • Pressure over hypothalamus causes hypothalamic syndromes.
    • A large tumor may press upon the third ventricle causing rise in intracranial pressure.
  2. Specific symptoms: These symptoms depend on the type of cell tumor
    • Acidophil adenoma causes acromegaly in adults and gigantism in younger patients.
    • Basophil adenoma causes Cushing's syndrome.
    • Chromophobe adenoma causes effects of hypo-pituitarism.
    • Posterior lobe damage causes diabetes insipidus.
Q.6. Describe pituitary gland under following heads:
(Dec 2010, 4 + 4 Marks)
a. Gross anatomy
b. Microscopic anatomy
Ans. For gross anatomy refer to Ans 5 of the same chapter.
For microscopic anatomy refer to Ans 19 of SECTION HISTOLOGY.
Q.7. Enumerate dural venous sinuses. Describe cavernous sinus and give its applied anatomy.
(Dec 2012, 2+4+2 Marks)
Ans. For enumeration refer to Ans 2 of the same chapter.
For description of cavernous sinus along with applied anatomy refer to Ans 3 of the same chapter.
Q.8. Write short note on tentorium cerebelli.
(Aug 2012, 5 Marks) (Nov 2008, 5 Marks)
Ans. Tentorium cerebelli is a tent shaped fold of dura mater which form roof of posterior cranial fossa.
  • It separates cerebellum from occipital lobes of cerebrum and divides cranial cavity into supratentorial and infratentorial compartments. Infratentorial compartment is the posterior cranial fossa consisting of hindbrain and lower part of midbrain.
  • Tentorium cerebelli consists of free margin as well as an attached margin. Anterior free margin is of U- shaped and is free. Ends of ‘U’ are attached anteriorly to anterior clinoid processes. Anterior margin bounds to tentorial notch which is occupied by the midbrain as well as the anterior part of superior vermis.
  • Outer or attached margin is convex and posterolaterally and it is attached to lips of transverse sulci on the occipital bone and on the posteroinferior angle of parietal bone. Anterolaterally, it is attached to superior border of the petrous temporal bone and to posterior clinoid processes. Along the attached margin, there are the transverse and superior petrosal venous sinuses.
  • Trigeminal or Meckel's cave is a recess of dura mater which is present in relation to attached margin of tentorium. Trigeminal cave is formed by evagination of the inferior layer of tentorium over the trigeminal impression on petrous temporal bone. It consists of trigeminal ganglion.
  • Free and attached margins of the tentorium cerebelli cross each other near the apex of the petrous temporal bone. Anterior to point of crossing, there is presence of triangular area which forms posterior part of roof of cavernous sinus, this is pierced by third and fourth cranial nerves.
  • Tentorium cerebelli consists of two surfaces i.e superior surface and inferior surface.
  • Superior surface is convex and it slopes to either side from median plane. Falx cerebri is attached to this surface in the midline; the straight sinus lies along the line of this attachment. Superior surface is related to the occipital lobes of the cerebrum.
  • Inferior surface is concave and fits to convex superior surface of cerebellum. Falx cerebelli is attached to its posterior part.
Venous sinuses enclosed in the tentorium cerebelli on each side are:
  1. Transverse sinus—Lies within the posterior part of the attached margin.
  2. Superior petrosal sinus—Present within the anterolateral part of the attached margin.
  3. Straight sinus—Present along the line of attachment between falx cerebri and tentorium cerebelli.77
zoom view
Fig. 97: Tentorium cerebelli
Q.9. Write short note on Meckel's cave.
(Nov 2009, 5 Marks)
Ans. Meckel's cave is also known as trigeminal cave or cavum trigeminale.
It is an arachnoidal pouch containing cerebrospinal fluid.
It is formed by two layers of dura mater which are part of an evagination of the tentorium cerebelli near the apex of the petrous part of the temporal bone.
It envelops the trigeminal ganglion.
It is bounded by the dura overlying four structures:
  1. Superolaterally: The cerebellar tentorium
  2. Superomedially: The lateral wall of the cavernous sinus
  3. Medially: The clivus
  4. Inferolaterally: The posterior petrous face.
Q.10. Write a short note on Rathke's Pouch.
(Dec 2010, 5 Marks)
Ans.
  • Anterior pituitary develops from a diverticulum that evaginates from the roof of the stomodeum in front of the buccopharyngeal membrane. This diverticulum is known as the Rathke's pouch.
  • Rathke's pouch extends up to the floor of the fore brain vesicle.
  • The Rathke's pouch separates from the stomatodeum by the second month due to growth of the surrounding mesenchyme.
  • The cells covering the anterior wall of the pouch gives rise to anterior lobe of pituitary.
  • The posterior wall of the pouch forms the par intermedia.
  • Cavity of the pouch persists as the intraglandular cleft.
  • The cephalic part of anterior lobe persists as the pars tuberalis.
  • Sometimes the stomodeal end of the pouch invades the roof of the nasopharynx and persists as the pharyngeal hypophysis.
zoom view
Fig. 100: Development of anterior and posterior lobe of pituitary
zoom view
Fig. 101: Rathke's pouch
78Q.11. Write about branches of internal carotid artery.
(Dec 2009, 5 Marks)
Ans. Internal carotid artery starts in the neck as terminal branch of common carotid artery. It is divided into four parts which gives off its branches.
 
Cervical Part
It lies in the carotid sheath. It does not give any branch.
 
Petrous Part
It is the part of temporal bone. It gives off caroticotympanic branches which enter middle ear and artery of pterygoid canal which enters pterygoid canal and anastomose with greater palatine artery.
 
Cavernous Part
In the cavernous sinus it gives off cavernous branch to trigeminal ganglion and superior and inferior hypophyseal branches to hypophysis cerebri.
 
Cerebral Part
It lies at base of the brain after emerging from cavernous sinus. It gives off ophthalmic, anterior cerebral, middle cerebral, posterior communicating and anterior choroidal branches.
zoom view
Fig. 102: Branches of internal carotid artery
Q.12. Enumerate the structures passing through cavernous sinus.
(Feb 2016, 2 Marks)
Ans. Following are the structures passing through the cavernous sinus:
Structures in the lateral wall of sinus from above to downwards:
  1. Oculomotor nerve
  2. Trochlear nerve
  3. Ophthalmic nerve
  4. Maxillary nerve
  5. Trigeminal ganglion.
Structures passingthrough the medial aspect of sinus:
  1. Internal carotid artery with venous and sympathetic plexus around it
  2. Abducent nerve.
Q.13. Write short note on trigeminal ganglion.
(Apr 2008, 3 Marks)
Ans. Trigeminal ganglion is the sensory ganglion of the fifth cranial nerve.
This ganglion is homologus with dorsal nerve root ganglia of spinal nerves.
It is made up of pseudounipolar nerve cells with a ‘T’- shaped arrangement of their processes.
The ganglion is crescentric or semilunar in shape with its convexity directed anterolaterally.
  • The three divisions of trigeminal nerve emerges from this convexity.
  • The posterior concavity of the ganglion receives the sensory root of the nerve.
 
Situation and Meningeal Relation
Trigeminal ganglion lies on the trigeminal impression over anterior surface of the petrous temporal bone near its apex. Here it occupies a special space of dura matter known as trigeminal cave or Meckel's cave. Two layers of dura are present below ganglion. Cave is lined by pia–arachnoid so that the ganglion along with motor root of trigeminal nerve is surrounded by cerebrospinal fluid. Ganglion lies at depth of 5 cm from the preauricular point.
 
Relations
  • Medially – Internal carotid artery and posterior part of cavernous sinus
  • Laterally – Middle meningeal artery
  • Superiorly – Parahippocampal gyrus
  • Inferiorly – Motor root of trigeminal nerve, greater petrosal nerve, apex of petrous temporal bone and foramen lacerum.
 
79Associated Root and Branches
  • Central process of ganglion cells forms the large sensory root of the trigeminal nerve which is attached to pons at its junction with the middle cerebellar peduncle.
  • Peripheral processes of the ganglion cells form three divisions of the trigeminal nerve, i.e. ophthalmic, maxillary and mandibular.
  • Small motor root of trigeminal nerve attach to the pons superomedial of the sensory root. It passes under the ganglion from its medial to lateral side and join mandibular nerve at the foramen ovale.
 
Blood Supply
  • Internal carotid artery
  • Middle meningeal artery
  • Accessory meningeal artery
  • Meningeal branch of ascending pharyngeal artery.
 
Applied Anatomy
Intractable facial pain due to trigeminal neuralgia or carcinomatosis may be abolished by injecting alcohol into the ganglion.
Q.14. Write the name of various paired intracranial venous system.
(Oct 2016, 2 Marks)
Ans. Various paired intracranial venous system are:
  • Cavernous
  • Superior petrosal
  • Inferior petrosal
  • Transverse
  • Sigmoid
  • Sphenoparietal
  • Petrosquamous
  • Middle meningeal
Q.15. Write short answer on venous sinuses of dura mater.
(Aug 2018, 3 Marks)
Ans. Venous sinuses of dura mater are the venous spaces, walls of which are formed by the dura mater.
  • They consist of an inner lining of epithelium.
  • There is no muscle present in their walls.
  • They also do not have any valves.
  • Venous sinuses of dura mater receive venous blood from the brain, meninges and bones of skull.
  • Cerebrospinal fluid is poured in some of them.
  • Cranial venous sinuses communicate with veins outside the skull via emissary veins. These communications keep blood pressure in sinuses constant.
  • There are 23 venous sinuses out of which 8 are paired and 7 are unpaired.
Paired Venous Sinus
  • Cavernous sinus
  • Superior petrosal sinus
  • Inferior petrosal sinus
  • Transverse sinus
  • Sigmoid sinus
  • Sphenoparietal sinus
  • Petrosquamous sinus
  • Middle meningeal sinus.
In above sinuses there is one sinus on each side.
Unpaired Venous Sinus
They are median in position:
  • Superior sagittal sinus
  • Inferior sagittal sinus
  • Straight sinus
  • Occipital sinus
  • Anterior intercavernous sinus
  • Posterior intercavernous sinus
  • Basilar plexus of veins.
 
13. CONTENTS OF THE ORBIT
Q.1. Give in tabular form the origin, insertion, nerve supply and action of extraocular muscles.
(Apr 2010, 5 Marks)
Enumerate extraocular muscles and mention their nerve supply.
(Sep 2001, 5 Marks)
Or
Name the extraocular muscles and write down their nerve supply.
(Mar 2013, 3 Marks)
Or
Write short note on extraocular muscles of eyeball.
(Oct 2014, 3 Marks)
Or
Write short note on recti muscles of eyeball.
(Feb 2014, 3 Marks)
Or
Write short answer on extraocular muscles.
(Apr 2018, 3 Marks)
Ans. Extraocular muscles are of two types:
  1. Voluntary muscles
    1. Four recti
      1. Superior rectus
      2. Inferior rectus
      3. Medial rectus
      4. Lateral rectus.
    2. Two oblique
      1. Superior oblique
      2. Inferior oblique.
    3. Levator palpabrae superioris.
  2. Involuntary muscles
    1. Superior tarsal muscle
    2. Inferior tarsal muscle
    3. Orbitalis.80
Voluntary muscles
Muscle
Origin
Insertion
Nerve supply
Action
Voluntary muscle
  1. Four recti
    1. Superior rectus
    2. Inferior rectus
    3. Lateral rectus
    4. Medial rectus
Four recti arise from a common annular tendon or tendinous ring of zim. Ring is attached to middle part of superior orbital fissure. Lateral rectus consists of an additional tendinous head which arises from orbital surface of greater wing of sphenoid bone lateral to tendinous ring
Recti are inserted into sclera little posterior to limbus
All recti are supplied by oculomotor nerve except lateral rectus which is supplied by abducent nerve
  1. Superior rectus: At vertical axis it elevates; At horizontal axis it adducts and at anteroposterior axis it rotates medially (intorsion)
  2. Inferior rectus: At vertical axis it depresses; At horizontal axis it adducts and at anteroposterior axis it rotates laterally (extorsion)
  3. Lateral rectus: At horizontal axis it abducts
  4. Medial rectus: At horizontal axis it adducts
  1. Two oblique muscle
    1. Superior oblique
    2. Inferior oblique
  1. It is arises from undersurface of lesser wing of sphenoid, superomedial to optic canal.
  2. It arises from the orbital surface of maxilla, lateral to lacrimal groove
  1. It is inserted into sclera behind equator of eyeball between superior and lateral rectus.
  2. It is inserted close. It is supplied by superior oblique a little below and posterior to later
  1. It is supplied by trochlear nerve
  2. It is supplied by oculomotor nerve
  1. Superior oblique: At vertical axis it depresses; At horizontal axis it abducts and at anteroposterior axis it rotates medially (intorsion)
  2. Inferior oblique: At vertical axis it elevates; At horizontal axis it abducts and at anteroposterior axis it rotates laterally (extorsion)
  1. Levator palpebrae superioris
It arises from the orbital surface of lesser wing of sphenoid, antero-superior to optic canal and origin to superior rectus
The flat tendon of levator splits into superior and inferior lamella superior is inserted to anterior surface of superior tarsus and skin of upper eyelid.
Inferior lamella is inserted to upper margin of superior tarsus and in superior conjunctival fornix
It is supplied by the oculomotor nerve
It elevates the upper eyelid.
zoom view
Fig. 103: Insertion of oblique and recti muscles of eyeball
 
Involuntary Muscles
zoom view
Fig. 104: Nerve supply of extraocular muscles
  • 81Superior tarsal muscle: It is the deep portion of levator palpabrae superioris. It is inserted on upper margin of superior tarsus. Elevates upper eyelid.
  • Inferior tarsal muscle: It extends from the facial sheath of inferior rectus and inferior oblique to lower margin of inferior tarsus. It depresses lower eyelid.
  • Orbitalis: It bridges inferior orbital fissure and its action is uncertain.
Q.2. Describe oculomotor nerve and mention its applied anatomy.
(Sep 2009, 10 Marks)
Or
Mention the course and distribution of oculomotor nerve.
(Sep 2002, 10 Marks)
Ans. It is a 3rd cranial nerve. It is distributed to both extraocular and intraocular muscles. It is in series with 4th, 6th and 12th cranial nerves along with ventral root of spinal nerves.
 
Functional Components
  • It is general somatic efferent for movements of eyeball.
  • Parasympathetic or general visceral efferent for contraction of pupil and accommodation.
  • General somatic afferent carry proprioceptive fibers from extraocular muscles to mesencephalic nucleus of trigeminal.
 
Nucleus
Oculomotor nucleus is situated in ventromedial part of central gray mater of midbrain at level of superior colliculus. Fibers for constrictor papillae and for ciliaris arise from Edinger–Westphal nucleus which forms part of oculomotor nuclear complex. Ventrolaterally, this is closely related to medial longitudinal bundle.
Connections of nucleus are:
  • To pyramidal tract of both sides which form supranuclear pathway of nerve.
zoom view
Fig. 105: Oculomotor nerve and its distribution
  • 82To pretectal nuclei of both sides for light reflex
  • To fourth, sixth and eighth nerve nuclei by medial longitudinal bundle for coordination of eye movements.
  • To tectobulbar tract for visuoprotective reflexes.
 
Course and Distribution
  • In its intraneural course, fibers arise from the nucleus and pass ventrally via tegmentum, red nucleus and substantia nigra.
  • At the base of brain, nerve get attached to oculomotor sulcus on medial side of crux cerebri.
  • Nerve passes between superior cerebellar and posterior cerebral arteries and run forward in interpeduncular cistern to reach cavernous sinus.
  • Now, the nerve enters cavernous sinus by piercing the posterior part of its roof over lateral side of posterior clenoid process. It descends into lateral wall of sinus where it lies above the trochlear nerve. In anterior part of sinus, nerve divides into superior and inferior division.
  • Both divisions of nerve enter orbit via middle part of superior orbital fissure. Inside the fissure, nasociliary nerve lies in between both the divisions but abducent nerve lies inferolateral to both divisions.
  • Inside the orbit, small upper division descends over lateral side of optic nerve supplies the superior rectus and levator palpebrae superioris. Larger lower division divides into three branches of medial rectus, inferior rectus and inferior oblique. Nerve to inferior oblique is the longest and gives off parasympathetic root to ciliary ganglion and then it supplies inferior oblique muscle.
  • All branches enter the muscles on their ocular surfaces except that for inferior oblique which enters from its posterior border.
 
Applied Anatomy
  • Complete and total paralysis of oculomotor results in:
    • Ptosis, dropping of upper eyelid.
    • Lateral squint.
    • Dilatation of pupil.
    • Loss of accommodation
    • Diplopia, double vision
    • Slight proptosis.
  • A midbrain lesion causing contralateral hemiplegia and ipsilateral paralysis of oculomotor nerve known as Weber's syndrome.
  • Supranuclear paralysis of 3rd nerve causes loss of conjugate movement of eye.
  • Ptosis or dropping of upper eyelid because of paralysis of voluntary part of levator palpabrae superioris muscle.
  • In an affected eye pupillary light reflex is absent.
  • Because of paralysis of parasympathetic fibers to sphincter papillae muscle there occurs dilatation of pupil.
  • Compression of oculomotor nerve: Due to extradural hematoma, compression of oculomotor nerve leads to dilatation of pupil. Parasympathetic fibers which lie superficially get affected first. Pupil dilates over affected side and there is little response to light.
Q.3. Write a short note on ciliary ganglion.
(Sep 2001, 4 Marks)
Ans. This is a peripheral parasympathetic ganglion placed in course of oculomotor nerve.
 
Location
It lies near apex of orbit between the optic nerve and tendon of lateral rectus muscle.
 
Roots
It has motor, sensory and sympathetic roots. Three roots enter its posterior end which is as follows:
  • The motor or parasympathetic root arises from nerve to inferior oblique. It consists of preganglionic fibers which begin in Edinger-Westphal nucleus. The fibers relay in ciliary ganglion. Postganglionic fibers arising in ganglion pass through short ciliary nerves and supply sphincter papillae muscles and ciliaris muscle. These intraocular muscles are used in accommodation.
  • The sensory root comes from nasociliary nerve. It consists of sensory fibers from eyeball. The fibers do not relay in ganglion.
  • The sympathetic root is branched from internal carotid plexus. It contains postganglionic fibers arising in superior cervical ganglion which pass along internal carotid, ophthalmic and long ciliary arteries. They pass out of ciliary ganglion without relay in short ciliary nerves to supply blood vessels of eyeball. They also supply to dilator papillae.
 
Branches
The ganglion gives off 8 to 10 short ciliary nerves which divides in 15 to 20 branches and then pierce sclera around entrance of optic nerve. They consist of fibers from all three roots of ganglion.
zoom view
Fig. 106: Ciliary ganglion and its roots
83Q.4. Write short note on nasociliary nerve.
(Sep 2011, 5 Marks)
Ans. It is one of the terminal branches of ophthalmic division of trigeminal nerve.
Nasociliary nerve begins in the lateral wall of anterior part of cavernous sinus. It enters orbit via middle part of superior orbital fissure between two divisions of oculomotor nerve. It crosses above the optic nerve from lateral to medial side along with ophthalmic artery and runs along medial wall of orbit between superior oblique and medial rectus. It ends at anterior ethmoidal foramen by dividing into anterior ethmoidal and infratrochlear nerves.
 
Branches
  • Sensory communicating branch to the ciliary ganglion form sensory root of ganglion. Often, it is mixed with sympathetic root.
  • Long ciliary nerves: They are 2 or 3 in number. These run on medial side of optic nerve, pierce sclera and supply sensory nerve to cornea, iris and ciliary body. These nerves also carry sympathetic nerve to dilator pupillae.
  • Posterior ethmoidal nerve: This passes through posterior ethmoidal foramen and supplies the ethmoidal and sphenoidal air sinuses.
  • Anterior ethmoidal nerve: This is the larger terminal branch of nasociliary nerve. It leaves orbit by passing through anterior ethmoidal foramen. It appears for very short distance in anterior cranial fossa over the cribriform plate of ethmoid. It then descends into the nasal cavity by passing through a slit at the side of anterior part of crista galli. Inside the nasal cavity the nerve lies deep to nasal bone. It gives off two internal nasal branches medial and lateral to mucosa of nose. Finally it emerges at lower border of the nasal bone as external nasal nerve which supply to skin of lower half of nose.
  • Infratrochlear nerve: This is the smaller terminal branch of nasociliary nerve which is given off at anterior ethmoidal foramen. This nerve emerges from orbit below trochlea for tendon of superior oblique and appears on face above medial angle of eye. It supplies to conjunctiva, lacrimal sac and caruncle, medial end of eyelid and upper half of external nose.
 
14. THE MOUTH AND PHARYNX
Q.1. Write a short note on vestibule of mouth.
(Feb 2002, 3 Marks) (Sep 2000, 4 Marks)
Ans. Vestibule of mouth is a narrow space bounded externally by lips and cheeks and internally by teeth and gums.
  • It communicates:
    1. With exterior through oral fissure
    2. With the mouth open it communicates freely with oral cavity proper.
  • Parotid duct opens on the inner surface of cheek opposite the crown of upper second molar teeth, numerous labial and buccal glands situated in submucosa of lips and cheeks open into vestibule. Four and five molar glands situated on buccopharyngeal fascia open inside the vestibule.
  • Except for the teeth, the entire vestibule is lined by mucous membrane. Mucous membrane form median folds which pass from lips to gums and is called as frenula of lips.
 
Applied Anatomy
  • Papilla of parotid duct inside the vestibule of mouth gives access to parotid duct for injection of radiopaque dye to locate calculi in ductal system or gland.
  • Koplik's spot are seen as white pin point spots around the opening of parotid duct in measles which are diagnostic of the disease.
Q.2. Write short note on gums.
(Apr 2010, 5 Marks)
Ans. It is also known as gingiva.
Gums are soft tissue which envelope the alveolar process of upper and lower jaws and surround neck of teeth.
Each gum has two parts:
  1. Free part surrounds the neck of the tooth like a collar.
  2. Attached part is firmly fixed to the alveolar arch of jaw. Fibrous tissue of gums is continuous with periosteum lining the alveoli.
 
Nerve Supply
  • Labial part of upper gums is supplied by posterior, middle and anterior superior alveolar nerves.
  • Lingual part of upper gums is supplied by anterior palatine and nasopalatine nerves.
  • Labial part of lower gums is supplied by buccal branch of mandibular and incisive branch of mental nerve.
  • Lingual part of lower gums is supplied by lingual nerve.
 
Lymphatic Drainage
Lymphatics of upper gum pass to submandibular nodes. The anterior part of lower gum drains into submental nodes, whereas posterior part drains into the submandibular nodes.
Q.3. Enumerate the muscles of palate.
(Sep 2000, 4 Marks)
Or
Enumerate muscles of soft palate.
(Feb 2002, 2 Marks)
(Sep 2017, 2 Marks)
Or
Describe briefly soft palate.
(Mar 2009, 5 Marks)
Ans. Soft Palate
  • It is a movable, muscular fold which is suspended from the posterior border of hard palate.
  • It separates nasopharynx from the oropharynx and is often looked as traffic controller as crossroads between the food and air passages.
  • Soft palate has two surfaces, anterior and posterior, and two borders, i.e. superior and inferior.
  • 84Anterior surface is concave and is marked by median raphe.
  • Posterior surface is convex and is continuous superiorly with the floor of nasal cavity.
  • Superior border is attached to the posterior border of hard palate blending on each side with pharynx
  • Inferior border is free and is bound to oropharyngeal isthmus. From its middle there hangs a conical projection known as uvula. From each side of base of uvula two curved folds of mucous membrane extend laterally and downwards. The anterior fold is called as palatoglossal arch or anterior pillar of fauces. It consists of palatoglossus muscle and reaches the side of tongue at junction of its both oral as well as pharyngeal parts. This fold creates the lateral boundary of oropharyngeal isthmus or isthmus of fauces. Posterior fold is known as palatophryngeal arch or posterior pillar of fauces. It consists of palatopharyngeous muscle. It leads to the formation of posterior boundary of tonsillar fossa and merges inferiorly with the lateral wall of pharynx.
 
Structure of Soft Palate
Soft palate is a fold of mucous membrane which consists of following parts:
  • Palatine aponeurosis: It is the flattened tendon of tensor veli palatine which form fibrous basis of palate. Near median plane, aponeurosis splits to enclose musculus uvulae.
  • Levator veli palatine and palatopharyngeus lie over superior surface of palatine aponeurosis.
  • Palatoglossus lie over inferior or anterior surface of palatine aponeurosis.
  • Numerous mucus glands as well as some of the taste buds are present at soft palate.
 
Enumeration of Muscles of Soft Palate
  1. Tensor palati: It tightens the soft palate chiefly anterior part.
    It opens the auditory tube to equalize air pressure between middle ear and nose.
  2. Levator palati: It elevates soft palate and closes pharyngeal isthmus.
  3. Musculus uvulae: It pulls up the uvula.
  4. Palatoglossus: It pulls up root of tongue, approximates pala-toglossal arches and thus closes oropharyngeal isthmus.
  5. Palatopharyngeus: It pulls up wall of pharynx and shortens it during swallowing.
 
Nerve Supply
  • Motor supply: All muscles of soft palate except tensor palati are supplied by pharyngeal plexus. Tensor palati is supplied by mandibular nerve.
  • General sensory nerves:
    • They are derived from middle and posterior lesser palatine nerves, which are branches of maxillary nerve via pterygopalatine ganglion.
    • Glossopharyngeal nerve
  • Special sensory or gustatory nerves carry taste sensations from oral surface and are contained in lesser palatine nerves. Fibers travel via greater petrosal nerve to geniculate ganglion of facial nerve and from here to nucleus of tractus solitaries.
  • Secretomotor nerves are present in lesser palatine nerves.
 
Blood Supply
Arterial Supply
  1. Greater palatine branch of maxillary artery.
  2. Ascending palatine branch of facial artery.
  3. Palatine branch of ascending pharyngeal artery.
Veins
They pass to pterygoid and tonsillor plexus of veins.
 
Lymphatics
It drains to upper deep cervical and retropharyngeal lymph nodes.
 
Applied Anatomy
  • Paralysis of muscles of soft palate due to lesion of vagus nerve produces
    • Nasal regurgitation of liquids
    • Nasal twang in voice
    • Flattening of the palatal arch on the side of lesion
    • Deviation of uvula opposite to the side of lesion.
  • Cleft palate is a congenital defect caused by non-fusion of right as well as left palatal processes. It can be of different degrees. In most severe case, cleft in palate is continuous with harelip while in least severe type, defect should be confined to soft palate.
Q.4. Write a note on Waldeyer's ring with applied anatomy.
(Feb 2002, 10 Marks)
Or
Answer in brief on Waldeyer's ring.
(Feb 2016, 2 Marks)
Or
Write short note on Waldeyer's lymphatic ring.
(Sep 2017, 2 Marks)
Ans. In relation to oropharyngeal isthmus, there are several aggregations of lymphoid tissue that constitute Waldeyer's lymphatic ring. The most important aggregations are right and left palatine tonsils usually referred to simply as the tonsils. Posteriorly and above there is prolaryngeal tonsil; laterally and above there are tubal tonsils over posterior part of dorsum of tongue.
Lymph from lymphoid tissue of this ring drains into precervical chain and deep cervical chain which constitutes external ring of Waldeyer.
 
Functions of Waldeyer's Ring
  • It filters the tissue fluid coming from inner surface of oral cavity.
  • It prevents entry of organism from outside and acts as a guard.
  • It acts as first line of defence and protect body against ingested and inspired bacteria by producing antibodies against invading organisms.85
zoom view
Fig. 107: Waldeyer's lymphatic ring
 
Applied Anatomy
Surgical neck dissection: Cancers arising in head and neck region from structures such as nasopharynx, paranasal air sinuses, oral cavity, oropharynx, larynx, and thyroid gland have predictable patterns of spread via chains of lymph nodes in neck.
When surgery is carried out to remove malignant lesion in this region, it is vitally important to understand these patterns of spread. Surgeons classify lymph nodes in neck into the following levels:
  • Level I nodes are in the submental and submandibular triangles.
  • Level II nodes lie around the upper portion of internal jugular vein and upper part of spinal accessory nerve. They extend from the base of the skull to the bifurcation of the common carotid artery or the hyoid bone.
  • Level III nodes lie around the middle third of the internal jugular vein and extend from inferior border of level II to the intermediate tendon of omohyoid (cricoid cartilage).
  • Level IV nodes lie around the lower third of the internal jugular vein and extend from the lower border of level III to the clavicle. It also includes supraclavicular lymph nodes.
  • Level V nodes are in the posterior triangle of the neck related to the spinal accessory nerve.
  • Level VI nodes are nodes surrounding the midline visceral structures and include the pretracheal and paratracheal nodes.
  • Level VII nodes are in the superior mediastinum.
Knowing which levels of nodes are likely to be involved during metastatic spread of a particular cancer, an appropriate nodal clearance is undertaken.
Classical radical neck dissection involves the removal of level I to level V nodes and removal of sternocleidomastoid muscle, internal jugular vein and spinal accessory nerve.
Modified radical neck dissection involves the removal of level I to V nodes but spares either or all of sternocleidomastoid muscle, internal jugular vein, and spinal accessory nerve.
The selective neck dissection involves some but not level I to V nodes.
Q.5. Write a short note on blood supply and clinical importance of palatine tonsil.
(Sep 2000, 4 Marks)
Or
Describe position, nerve supply, blood supply and applied importance of palatine tonsil.
(Sep 2000, 4 Marks)
Or
Write short note on palatine tonsil.
(Feb 2013, 5 Marks)
(June 2010, 5 Marks) (Nov 2009, 5 Marks)
(Aug 2011, 5 Marks)
Or
Write short note on blood supply of palatine tonsil.
(Sep 2017, 3 Marks)
Or
Write a note on blood supply of palatine tonsil.
(Sep 2006, 3 Marks)
Or
Describe palatine tonsil under following headings:
(Aug 2018, 10 Marks)
a. External features
b. Tonsillar bed
c. Nerve supply and blood supply
d. Applied anatomy
Ans. Position
Palatine tonsil occupies the tonsillar fossa between palatoglossal and palatopharyngeal arches. It can be seen through the mouth.
zoom view
Fig. 108: Palatine tonsils
 
External Features
Palatine tonsil consists of surfaces i.e. medial and lateral; two borders, i.e. anterior and posterior and two poles, i.e. upper and lower pole.
  • Medial surface: It is covered by stratified squamous epithelium and is continuous with that of mouth. Medial surface consists of 12 to 15 crypts. Largest cleft is known as intratonsillar cleft. The cleft is semilunar in shape and is parallel to dorsum of tongue.
  • Lateral surface: It is covered by sheet of fascia which forms hemicapsule of tonsil. Capsule is an extension of pharyngobasilar fascia. Capsule is only loosely attached to muscular wall of pharynx and is formed here by superior constrictor and styloglossus, but anteroinferiorly capsule is firmly adherent to side of tongue just infront of insertion on palatoglossus and palatopharyngeus muscle. This attachment keeps the tonsil in place during swallowing.
    • 86Tonsillar artery enters the tonsil by piercing superior constrictor just behind firm attachment.
    • Palatine vein descends from the palate in loose areolar tissue on lateral surface of capsule and crosses tonsil before piercing wall of pharynx.
    • More laterally, there is facial artery with its tonsillar and ascending palatine branches. Internal carotid artery is 2.5 cm posterolateral to tonsil.
  • Anterior border: It is related to palatoglossal arch along with its muscle.
  • Posterior border: It is related to palatopharyngeal arch along with its muscle.
  • Upper pole: It is related to soft palate.
  • Lower pole: It is related to tongue.
  • Plica triangularis is a triangular vestigial fold of mucus membrane covering anteroinferior part of tonsil.
  • Plica semilunaris is the semilunar fold which may cross upper part of tonsillar sinus.
 
Tonsillar Bed
The bed of tonsil is formed from within outwards by:
  • Pharyngobasilar fascia
  • Superior constrictor and palatopharyngeous muscles
  • Buccopharyngeal fascia
  • In the lower part, the styloglossus
  • The glossopharyngeal nerve.
zoom view
Fig. 109: Arterial supply of palatine tonsils
 
Blood Supply
  1. Arterial supply
    1. Main source: Tonsillar branch of facial artery.
    2. Additional source:
      1. Ascending palatine branch of facial artery
      2. Dorsal lingual branch of lingual artery
      3. Ascending pharyngeal branch of external carotid artery
      4. Greater palatine branch of maxillary artery.
  2. Venous drainage: One or more veins leave the lower part of deep surface of tonsil, pierce superior constrictor and join palatine pharyngeal or facial vein.
 
Lymphatic Drainage
Lymphatics pass to jugulodigastric node.
 
Nerve Supply
It is mainly supplied by the two nerves, i.e.
  1. Glossopharyngeal nerve
  2. Lesser palatine nerve
 
Applied Importance or Clinical Importance
  1. Tonsillectomy is usually done by guillotine method. Hemorrhage after tonsillectomy is checked by removal of clot from raw tonsillar bed. This is to be compared for method of checking postpartum hemorrhage from uterus. These are only two organs in body where bleeding is checked by removal of clots. In other parts of body clot formation is encouraged.
  2. Tonsillitis may cause referred pain in ear.
  3. Suppuration in peritonsillar area is called quinsy. A peritonsillar abscess is drained by making an incision at most prominent point of abscess.
  4. Tonsils are often the site of septic focus. Such focus can lead to serious diseases like pulmonary tuberculosis, meningitis, etc.
  5. Tonsils are larger in children and they retrogress after the puberty.
Q.6. Enumerate the muscles of pharynx with their nerve supply.
(Sep 2002, 2 Marks)
Ans. Constrictors of Pharynx
There are three constrictors of pharynx namely:
  1. Superior constrictor
  2. Middle constrictor
  3. Inferior constrictor
zoom view
Fig. 110: Constrictor and longitudinal muscles of the pharynx
87The above muscles are supplied by pharyngeal plexus. Pharynx also consists of three muscles which run longitudinally
  1. Stylopharyngeus
  2. Palatopharyngeus
  3. Salpingopharyngeus.
 
Nerve Supply
  • Motor fibers are derived from cranial accessory nerve through branches of vagus, they supply all muscles of pharynx except stylopharyngeus which is supplied by glossopharyngeal nerve.
  • Inferior constrictor receives an additional supply external and recurrent laryngeal nerves.
Q.7. Write a short note on constrictor muscles of pharynx.
(Mar 2000, 4 Marks)
Or
Write briefly on constrictors of pharynx.
(Aug 2012, 5 Marks)
Ans. Muscular basis of wall of pharynx is formed by three constrictors, i.e. superior, middle and inferior.
 
Origin
Origin of constrictors is situated anteriorly in relation to posterior openings of nose, mouth and larynx. From here the fibers of muscles pass to lateral and posterior walls of pharynx, fibers of two side meet in midline in fibrous raphe.
  • Superior constrictor originates from:
    • Pterygoid hamulus
    • Pterygomandibular raphae
    • Medial surface of mandible at posterior end of mylohyoid line
    • Side of posterior part of tongue.
  • Middle constrictor originates from:
    • Lower part of stylohyoid bone
    • Lesser cornue of hyoid bone
    • Upper border of greater cornue of hyoid bone.
  • Inferior constrictor consists of two parts, i.e. the thyropharyngeous part which originates from thyroid cartilage and cricopharyngeal part which originates from cricoid cartilage.
 
Insertion of Constrictors
Arrangement of all three constrictors is like that the inferior constrictor overlaps the middle constrictor which in turn overlaps superior constrictor.
All the three constrictors of pharynx inserted inside the median raphe on posterior wall of pharynx. Upper end of raphe reaches to base of skull where it is attached to pharyngeal tubercle on basilar part of occipital bone.
 
Nerve Supply
  • Superior constrictor and middle constrictor are supplied by pharyngeal branch of vagus nerve carrying fibers of cranial root of accessory nerve.
  • Thyropharyngeus part of inferior constrictor is supplied by pharyngeal plexus and external laryngeal nerve, while cricopharyngeus part is supplied by the recurrent laryngeal nerve.
 
Action of Constrictors of Pharynx
All the constrictors help in deglutition.
zoom view
Fig. 111: Origin of constrictors of pharynx
88Q.8. Describe anatomy of pharynx with its blood supply and lymphatic drainage. Add a note on mechanism of deglutition.
(Sep 2011, 15 Marks)
Ans. Anatomy of Pharynx
Pharynx is a wide muscular tube which is situated behind the nose, mouth and larynx.
 
Boundaries
  • Superiorly: It is bounded by base of skull including posterior part of body of sphenoid and basilar part of occipital bone in front of pharyngeal tubercle.
  • Inferiorly: It is continuous with esophagus at the level of sixth cervical vertebrae corresponding to the lower border of cricoid cartilage.
  • Posteriorly: Pharynx glides freely over prevertebral fascia which separates it from cervical vertebral bodies.
  • Anteriorly: Its communication is with nasal cavity, oral cavity and larynx, so anterior wall is incomplete.
  • Over each side:
    • Pharynx gets attached to medial pterygoid plate, pterygomandibular raphae, mandible, tongue, hyoid bone, thyroid and cricoid cartilages.
    • Pharynx communicates on each side with middle ear cavity via auditory tube.
    • Pharynx is related on either side to styloid process and muscles attached to it, common carotid, internal carotid and external carotid arteries along with the cranial nerves related to them.
 
Parts of Pharynx
Pharynx is divided into three parts from above downwards which are as follows:
  1. Nasopharynx, lie behind the nose
  2. Oropharynx, lie behind the oral cavity
  3. Laryngopharynx, lie behind the larynx
 
Structure of Pharynx
The wall of pharynx is composed of the following five layers from within outwards.
  1. Mucosa
  2. Submucosa
  3. Pharyngobasilar fascia: This is a fibrous sheet internal to pharyngeal muscles. It is thickest in upper part where it fills the gap between upper border of the superior constrictor and base of skull, and also posteriorly where it forms pharyngeal raphae. On its superior aspect, fascia get attached to basiocciput, petrous temporal bone, auditory tube, posterior border of medial pterygoid plate and pterygomandibular raphae. Over its inferior aspect, it lost gradually deep to muscles and does not extend beyond superior constrictor muscle.
  4. Muscular coat: It consists of an outer circular layer made up of three constrictors and an inner longitudinal layer made up of stylopharyngeus, salpingopharyngeus and palatopharyngeus muscles.
  5. Buccopharyngeal fascia: It covers outer surface of constrictor of pharynx and extend forwards across pterygomandibular raphae to cover the buccinator. Between the buccopharyngeal fascia and pharyngeal coat there lies pharyngeal plexus of veins and nerves.
zoom view
Fig. 112: Anatomy of pharynx
 
Blood Supply
Arterial Supply
Arteries supplying pharynx are:
  1. Ascending pharyngeal branch of external carotid artery
  2. Ascending palatine and tonsillar branches of facial artery
  3. Dorsal lingual branches of lingual artery
  4. Greater palatine, pharyngeal and pterygoid branches of maxillary artery.
Venous Drainage
Veins form a plexus on posterolateral aspect of pharynx and collects blood from pharynx, soft palate and prevertebral region. It drains into internal jugular vein and facial vein.
 
Lymphatic Drainage
It drains to retropharyngeal and deep cervical lymph nodes.
 
Mechanism of Deglutition or Swallowing
Swallowing of food occurs in three stages.
First Stage
  • First stage is voluntary in character.
  • Anterior part of tongue gets raised and is pressed against hard palate by intrinsic muscles of tongue mainly the superior longitudinal and transverse muscles.
  • Movement occurs from anterior to posterior side which pushes food bolus to oropharynx.
  • Now the soft palate closes down on the back of tongue and helps to form bolus.
  • 89Hyoid bone move upwards as well as forward by suprahyoid muscles. Posterior part of tongue gets elevated upward and backward by styloglossi and palatoglossal arches get approximated by palatoglossi. This causes pushing of bolus via oropharyngeal isthmus to oropharynx.
Second Stage
  • The stage is involuntary in character. During this food get pushed from oropharynx to lower part of laryngopharynx.
  • Nasopharyngeal isthmus is closed by elevation of soft palate which occur due to levator veli palatine and tensor veli palatine and by approximation to it of posterior pharyngeal wall. This stops food bolus from entering nose.
  • Inlet of larynx gets closed by approximation of aryepiglottic fold by aryepiglottic and oblique arytenoid. This stops food bolus from entering to larynx.
  • Larynx and pharynx are elevated behind hyoid bone with the help of longitudinal muscles of pharynx and bolus is pushed over posterior surface of epiglottis, closed inlet of larynx and posterior surface of arytenoids cartilages due to gravity and by contraction of superior and middle constrictors and of palatopharyngeus.
Third Stage
  • It is involuntary in character.
  • During this stage food passes from lower part of pharynx to esophagus which is brought about by inferior constrictors of pharynx.
Q.9. Write a short note on auditory tube.
(Sep 2002, 3 Marks) (Apr 2007, 4 Marks)
Ans.
  • It is also known as pharyngotympanic tube or Eustachian tube.
  • Auditory tube is trumpet shaped channel which connect middle ear cavity with nasopharynx.
  • This is 4 cm long and is directed downward, forward and medially.
  • Auditory tube forms an angle of 45° with sagittal plane and 30° with horizontal plane.
 
Parts of Auditory Tube
The tube is divided into bony and cartilaginous parts:
Bony Part
Bony part forms the posterior one-third of the tube. It is 12 mm long, and lies in petrous temporal bone near tympanic plate. Its lateral end is wide and opens on the anterior wall of middle ear cavity. The medial end is narrow and is jagged for attachment of cartilaginous part. Lumen of tube is oblong which is widest from side to side.
Relations of Bony Part
  • Superior: Canal for tensor tympani
  • Medial: Carotid canal
  • Lateral: Chorda tympani, spine of sphenoid, auriculotemporal nerve and temporomandibular joint.
Cartilagenous Part
It forms anterior and middle two-third of the auditory tube. This is 25 mm long and lie inside sulcus tubae. This part is made up of a triangular plate of cartilage which is curled to form the superior and medial walls of auditory tube. Lateral wall as well as floor gets completed by fibrous membrane. Apex of the plate gets attached to medial end of bony part. Base is free and forms tubal elevation in nasopharynx.
Relations of Cartilaginous Part
  • Anterolaterally: Tensor veli palatini, mandibular nerve with its branches, otic ganglion, chorda tympani, middle meningeal artery and medial pterygoid plate.
  • Postermedially: Petrous temporal bone and levator veli palatini.
  • Levator veli palatine get attached to its inferior surface and salpingopharyngeus to its lower part near pharyngeal opening.
 
Blood Supply
  • Arterial supply of tube is derived from ascending pharyngeal and middle meningeal artery and artery of pterygoid canal.
  • Veins drain to pharyngeal and pterygoid plexus of veins.
  • Lymphatics pass to retropharyngeal nodes.
 
Nerve Supply
  • At ostium by pharyngeal branch of the pterygopalatine ganglion.
  • Cartilaginous part by nervous spinosus.
  • Bony part by tympanic plexus which is formed by the glossopharyngeal nerve.
 
Function
Auditory tube provide communication of middle car cavity with the exterior which ensure equal air pressure over both sides of tympanic membrane.
zoom view
Fig. 113: Auditory tube
Q.10. Write the external features of various teeth and draw diagram of basic internal structure of canine tooth.
(Feb 2005, 15 Marks)
Ans. External Features of Various Teeth
Incisors
They are four in each jaw, two on each side of median plane. They are arranged in two groups: Two medial incisors and two lateral incisors. The four upper incisors are carried by the premaxillary portion of the maxilla. As the name suggests, the incisors cut the food by their cutting edges. They are chisel like. The upper and 90lower incisors do not meet edge to edge but by a sliding overlap like the blades of a pair of scissors. These teeth has single root.
Canines
There are two canines on each jaw, one on each side lateral to the incisors. They are so named because they are prominent in dogs (carnivorous animals). The canines are holding and tearing teeth with conical and rugged crowns. They are sometimes referred to as cuspids (or eye teeth). They are long teeth and usually the last deciduous teeth to be lost. The middle labial lobes have been highly developed incisally into strong well-formed cusps. In function, the canines support incisors and premolars, since they are located between these groups. Canines are the single rooted teeth.
Premolars
They are four in number, i.e. two in the maxilla and two in the mandible. They are posterior to canines and anterior to molars. They are generally bicuspid. The buccal cusp of maxillary first premolar is long and sharp assisting the canine as prehensile or tearing tooth. The mandibular first premolar assists mandibular canine in same manner.
The second premolars, both maxillary and mandibular, have cusps less sharp than others, and their cusps articulate with opposing teeth where jaws are brought together. This makes them more efficient as grinding teeth. All premolars have single root except for maxillary first premolar which has bifid root.
Molars
These teeth assist the mandibular molars in performing major portion of work in mastication and grinding of food. They are largest and strongest maxillary teeth. Maxillary molars have large crowns with four well-developed cusps. Mandibular molars are larger than any other mandibular teeth and they have five cusps on their crown. They are three in number on each side of mandible. Third molars and some mandibular second molars have two roots while maxillary molars have three roots. All mandibular molars have crown which are roughly quadrilateral. Mandibular permanent molars are the strongest mandibular teeth because of their bulk and anchorage.
 
Diagram of Internal Structure of Canine Tooth
zoom view
Fig. 114: Internal structure of canine
Q.11. Describe various nerves which supply teeth.
(Aug 2005, 15 Marks) (Mar 2010, 10 Marks)
Ans. Teeth are supplied by the branches of trigeminal nerve.
Branches of trigeminal nerve are ophthalmic, maxillary and mandibular.
 
Maxillary Branch
  • It supplies maxillary teeth. During its course when it passes through pterygopalatine fossa it gives 5 branches out of which one is posterior superior alveolar branch.
zoom view
Fig. 115: Nerve supply of teeth
  • 91An internal branch of posterior superior alveolar nerve goes along with a branch of the maxillary artery through the posterior alveolar canal which opens on the posterior surface of the maxilla.
  • In the bone nerve passes down the posterior or posterolateral wall of the maxillary sinus, giving of sensory fibers. It then supplies the maxillary molars except the mesiobuccal root of the first molar.
  • Within the depth of the alveolar bone or tooth socket some nerve fiber passes to supply the periodontal ligament where as other, the pulpal fibers passes through the apical foramina of the roots of the molar teeth to supply the dental pulp.
  • When maxillary nerve passes through inferior orbital groove and canal it gives
    1. Middle superior alveolar nerve: From inferior orbital canal it passes in a downward and anterior direction and supplies the maxillary bicuspid and mesiobuccal root of the first molar.
    2. Anterior superior alveolar nerve: The anterior superior alveolar nerve descends in fine canal in the maxilla to pass the roots of the maxillary central, lateral incisor and canine teeth.
 
Mandibular Division
  • It supplies mandibular teeth.
  • Inferior alveolar nerve which is the largest of the branches of the posterior division of the mandibular part of the trigeminal nerve supply mandibular teeth
  • In the inferior alveolar canal it gives off branches to the mandibular teeth as apical fibers that enter the apical foramina of the mandibular teeth to supply the dental pulp of mandibular molars and bicuspid.
  • As the inferior alveolar nerve reaches the region of mental foramina it gives incisive branch which form a fine incisive plexus that supplies the cuspid tooth and the incisor teeth.
Q.12. Describe the parts, structure, and time of eruption, development and clinical anatomy of teeth.
(Mar 2006, 10 Marks)
Ans. Parts of the tooth
Each tooth consists of the following three parts:
  1. Crown: Anatomical crown is the part of tooth that is covered by enamel whereas clinical crown is the part which projects in oral cavity.
  2. Root: This is embedded within the socket of jaw beneath the gum.
  3. Neck: It is the part of tooth present between the crown and root and is surrounded by the gum.
 
Structure of the Tooth
Structurally, each tooth is composed of:
  1. Pulp:
    • It is found in the center of the tooth.
    • Pulp is a loose fibrous connective tissue containing vessels nerves and lymphatics, all of which enter the pulp cavity through apical foramen.
    • Pulp is covered by a layer of tall columnar cells called as odontoblasts which are capable of replacing dentin during any time in life.
  2. Dentin
    • It is a calcified material containing spiral tubules radiating from the pulp cavity.
    • Each tubule is occupied by protoplasmic process from one of the odontoblasts.
    • The calcium and organic matter are in same proportion as in bone.
  3. Enamel
    • It is the hardest substance in the body.
    • It is made up of crystalline prisms laying roughly at the right angles to the surface of tooth.
  4. Cementum
    • It is the boney covering over the neck and root of the tooth but like enamel and dentin it has neither blood supply nor any nerve supply.
    • Over the neck, cementum overlaps cervical end of enamel or less commonly it can just meet enamel.
  5. Periodontal membrane (ligament)
    • It holds the root in its socket.
    • It is present between the cementum and the socket of the root.
    • It acts as periosteum to both cementum and bony socket.
zoom view
Fig. 116: Structure of tooth
 
Time of Eruption
Age of eruption of deciduous teeth
Tooth
Maxillary
Mandibular
Central Incisor
7 months
6 months
Lateral Incisor
9 months
7 months
Canine
18 months
16 months
First Molar
14 months
12 months
Second Molar
24 months
20 months
92
Age of eruption of permanent teeth
Tooth
Maxillary
Mandibular
Central Incisor
7–8 years
6–7 years
Lateral Incisor
8–9 years
7–8 years
Canine
11–12 years
9–10 years
First Premolar
10–11 years
10–12 years
Second Premolar
10–12 years
11–12 years
First Molar
6–7 years
6–7 years
Second Molar
12–13 years
11–13 years
Third Molar
17–21 years
17–21 years
 
Development of Teeth
Refer to Ans 1 of chapter ALIMENTRY SYSTEM I: MOUTH, PHARYNX AND RELATED STRUCTURES of EMBRYOLOGY SECTION.
 
Clinical Anatomy
  1. Decalcification of enamel and dentin with consequent softening and gradual destruction of the tooth is known as dental caries. A carious tooth is tender and mastication is painful.
  2. Irregular dentition is common in rickets and upper permanent incisors are notched. In congenital syphilis also the same teeth are notched but the notching corresponds to a large segment of a small circle, i.e. hutchinson's teeth.
  3. As tooth is the hardest and chemically most stable tissue in body it is preserved after death and may be fossilized, due to this property teeth are very helpful in medicolegal practice for identification of unrecognized dead bodies.
  4. Infection of apex of root of tooth, i.e. periapical abscess occurs when pulp is dead. This condition is seen on a radiograph.
  5. Third molars or wisdom teeth erupt at the age of 18 to 20 years, they may not erupt normally because of less space and get impacted causing severe pain. If persist for longer duration can lead to dentigerous cyst.
  6. Time of eruption of tooth helps in age assessment.
  7. Improper oral hygiene can lead to gingivitis and suppuration with pocket formation between gums and teeth. This leads to chronic pus discharge at margin of gums. This condition is called as pyorrhea alveolaris. It is the common cause of foul breadth and patient hardly consult the dentist as the condition is painless.
  8. Maxillary canines are known as eye teeth as they consist of long roots which reach to medial angle of eye. Infection of these roots can spread to facial vein and causes thrombosis of cavernous sinus.
  9. Maxillary teeth need separate injections of anesthetic over both buccal as well as palatal surfaces of maxillary process just distal to tooth. Thin layer of bone permit rapid diffusion of drug upto the tooth.
Q.13. Write a short note on structure of tooth.
(Mar 2006, 3 Marks) (Dec 2014, 5 Marks)
(Apr 2017, 4 Marks)
Or
Write short note on parts and structure of tooth.
(May 2017, 3 Marks)
Ans. Refer to Ans 12 of the same chapter.
Q.14. Enumerate deciduous teeth and their age of eruption.
(Sep 2006, 3 Marks)
Ans. Refer to Ans 12 of the same chapter.
Q.15. Write a short note on baby teeth.
(Sep 2006, 3 Marks)
Ans. Baby teeth are also known as deciduous teeth or primary teeth or milk teeth.
  • Deciduous teeth begin to form prenatally at about 14 weeks in intrauterine life and completed postnatally at 3 years of age.
  • Deciduous teeth begin to erupt at about 6 months and all get erupted by end of second year or soon after.
  • Teeth of lower jaw erupt slightly earlier than those compared to upper jaw.
  • Deciduous teeth remain intact till 6 years of age. At about that time permanent teeth begin to erupt in mouth.
  • For time of eruption of deciduous teeth refer to table in Ans 12 of the same chapter.
  • For dental formula of deciduous teeth refer to Ans 24 of same chapter.
Q.16. Write a short note on Gomphosis.
(Apr 2008, 3 Marks)
Ans. It is also called as articulation dentoalveolaris.
  • Gomphosis is a type of fibrous joint.
  • It is a peg and socket junction between tooth and its socket.
  • Periodontal ligament connects dental element to alveolar nerve.
  • Gomphosis is an articulation between two bones.
Q.17. Write a short note on muscles of soft palate.
(Oct 2007, 5 Marks)
Or
Write briefly on muscles of soft palate.
(Dec 2010, 5 Marks)
Ans. Muscles of Soft Palate
zoom view
Fig. 117: Muscles of soft palate
93
Muscles of soft palate
S. No.
Muscle
Origin
Insertion
Action
1.
Tensor Palati
  1. Lateral side of the auditory tube
  2. Adjoining part of the base of the skull
Muscle desends, converges to form a delicate tendon which winds round the hamulus, passes through the origin of the buccinator, and flattens to form palatine aponeurosis.
Aponeurosis is attached to:
  1. Posterior border of hard palate.
  2. Inferior surface of hard palate behind the palatine crest.
  1. Tightens the soft palate, chiefly anterior part.
  2. Opens the auditory tube to equalize the air pressure between the middle ear and the nasopharynx
2.
Levator Palati
  1. Medial aspect of auditory tube.
  2. Adjoining part of inferior surface of petrous temporal bone
Muscle enter pharynx by passing upper concave margin of superior constrictor muscle, it run downward and medially and spread out inside the soft palate. It is inserted on upper surface of palatine aponeurosis
  1. Elevate soft palate to close pharyngeal isthumus
  2. Helps in opening the auditory tube
3.
Musculus Uvulae
  1. Posterior nasal spine
  2. Palatine aponeurosis
Mucous membrane of uvula
Pulls up uvula forwards to its own side
4.
Palatoglossus
Oral surface of palatine aponeurosis
Descends in palatoglossal arch, to the side of the tongue at the junction of its oral and pharyngeal parts.
Pulls up root of tongue, approximate palatoglossal arches, and thus closes oropharyngeal isthumus
5.
Palatopharyn geus
  1. Anterior fasciculus: From posterior border of hard palate
  2. Posterior fasciculus: From palatine aponeurosis.
Descend in the palatopharyngeal arch and spreads out to form the greater part of longitudinal muscle coat of pharynx.
It is inserted into:
  1. Posterior border of lamina of the thyroid cartilage
  2. Wall of the pharynx and its median raphae
Pulls up the wall of pharynx and shortens it during swallowing
Q.18. Write a note on palate.
(Mar 2008, 3 Marks)
Ans. It is the partition between the nasal cavity and oral cavity. It is of two types: Hard palate and soft palate
 
Hard Palate
Its anterior two-third are formed by the palatine process of maxilla and its posterior one-third by the horizontal plates of the palatine bones.
The anteriolateral margins of the palate are continuous with the alveolar arches and gums.
The posterior margin gives attachment to the soft palate.
The superior surface forms the floor of the nose and the inferior surface forms the roof of the oral cavity.
Vessels and Nerves
  • Arteries: Greater palatine branches of maxillary artery.
  • Veins: Go to the pterygoid plexus of veins.
  • Nerves: Greater palatine and nasopalatine branches of the pterygopalatine ganglion.
  • Lymphatics: They drain mostly to the upper deep cervical nodes and partly to the retropharyngeal nodes.
 
Soft Palate
Refer to Ans 3 of same chapter.
Q.19. Describe soft palate under following headings.
(Nov 2009, 10 Marks)
a. Gross anatomy
b. Muscles and nerves
c. Applied
Ans.
  1. For gross anatomy refer to Ans 3 of same chapter.
  2. For muscles refer to Ans 17 and for nerves refer to Ans 3 of same chapter.
  3. For applied anatomy refer to Ans 3 of same chapter.
Q.20. Draw well labeled diagram of structures seen in oral cavity (with mouth wide open).
(Dec 2009, 5 Marks)
Or
Draw a well labeled diagram to show the structures seen in the oral cavity in a fully opened mouth.
(Oct 2016, 5 Marks)
94Ans.
zoom view
Fig. 116: Structures seen in oral cavity (with mouth wide open)
Q.21. Write briefly on structure of cheek.
(Aug 2011, 5 Marks)
Ans. Cheeks are fleshy flaps which forms large part of each side of the face.
Cheeks are continuous in front with the lips, and the junction is indicated by the nasolabial sulcus or furrow which extends from the side of the nose to the angle of the mouth.
Each cheek is composed of:
  1. Skin
  2. Superficial fascia containing some facial muscles, parotid duct, mucous molar glands, vessels and nerves
  3. Buccinator covered by bucopharyngeal fascia and pierced by the parotid duct
  4. Submucosa with mucous buccal glands
  5. Mucous membrane.
Buccal pad of fat is best developed in infants and lies on the buccinator partly deep to the masseter and partly in front of it.
Lymphatics of the cheek drain chiefly into the sub-mandibular and preauricular nodes and partly also to the buccal and mandibular nodes.
Q.22. Write short note on bed of tonsil.
(Oct 2014, 3 Marks)
Or
Enumerate the only structures forming bed of tonsil.
(Sep 2005, 4 Marks)
Ans. Bed of tonsil is formed from within outwards by:
  • Pharyngobasilar fascia
  • Superior constrictor and palatopharyngeus muscle
  • Buccopharyngeal fascia
  • In lower part, styloglossus
  • Glossopharyngeal nerve.
Q.23. Write short note on dental formula.
(May 2008, 3 marks)
Ans. The number and type of teeth present in the oral cavity in one half of the face (either left side or right side) in primary dentition are expressed by the following formula:
zoom view
  • In this formula each tooth is represented by its initial letter. I for incisor, C for canine and M for molar.
    • Each letter is followed by a horizontal line and the number of each type of tooth is placed above the line for maxilla and below the line for the mandible.
    • The formula includes one side only. The above formula should be read thus:
      Incisors: Two maxillary and two mandibular.
      Canines: One maxillary and one mandibular.
      Molars: Two maxillary and two mandibular.
      95Similarly for permanent dentition (either left side or right side), the dental formula is as follows:
      zoom view
      In this premolars have now been added to the formula.
      In the case of permanent teeth, the formula should be read as:
      Incisors: Two maxillary and two mandibular.
      Canines: One maxillary and one mandibular.
      Premolars: Two maxillary and two mandibular.
      Molars: Three maxillary and three mandibular.
      To understand dental anatomy, the nomenclature should be read first.
Q.24. Answer in brief dental formula for deciduous child.
(May 2017, 3 Marks)
Ans. The number and type of teeth present in the oral cavity in one half of the face (either left side or right side) in primary dentition are expressed by the following formula.
zoom view
  • In this formula each tooth is represented by its initial letter. I for incisor, C for canine and M for molar.
  • Each letter is followed by a horizontal line and the number of each type of tooth is placed above the line for maxilla and below the line for the mandible.
  • The formula includes one side only. The above formula should be read thus:
    Incisors: Two maxillary and two mandibular.
    Canines: One maxillary and one mandibular.
    Molars: Two maxillary and two mandibular.
    To understand dental anatomy, the nomenclature should be read first.
Q.25. Write short note on effect if soft palate is paralyzed.
(May 2017, 3 Marks)
Ans. Following are the effects produced if soft palate gets paralyzed:
  • Nasal regurgitation of liquids
  • Nasal twang in voice
  • Flattening of palatal arch on side of lesion
  • Deviation of uvula, opposite to side of lesion.
Q.26. Enumerate type of pharynx.
(Apr 2018, 2 Marks)
Ans. Pharynx is divided into three parts from above downwards which are as follows:
  • Nasopharynx, lie behind the nose
  • Oropharynx, lie behind the oral cavity
  • Laryngopharynx, lie behind the larynx.
Q.27. Write very short answer on oral diaphragm.
(Aug 2018, 2 Marks)
Ans. Oral diaphragm is also known as floor of the mouth.
  • The floor of the mouth is a small horseshoe-shaped region situated beneath the anterior two-third of the tongue and above the muscular diaphragm formed by two mylohyoid muscles.
  • The surface of the floor is formed by mucus membrane, which connects the tongue to the mandible.
  • Laterally the mucus membrane passes from the side of the tongue onto the mandible.
  • Anteriorly the mucus membrane stretches from one half of the mandible to the other. The anterior part of the floor is called sublingual region, which intervenes between the ventral surface of the anterior two-third of the tongue and the floor of the mouth.
  • Clinical anatomy: The swellings of the submandibular gland can be palpated bimanually by putting an index finger in the mouth and thumb below the angle of the jaw in relation to the position of gland, because part of the gland lies in the oral cavity above the floor of the mouth and part outside the oral cavity below the floor of the mouth. The submandibular lymph nodes lying on the surface of the gland cannot be palpated bimanually as they lie below the floor of the mouth (oral diaphragm). Thus an enlarged submandibular gland can be differentiated from a mass of the submandibular lymph nodes by bimanual palpation.
 
15. THE NOSE AND PARANASAL SINUSES
Q.1. Describe gross anatomy, blood supply, nerve supply and applied anatomy of nasal septum.
(May/June 2009, 15 Marks)
Or
Describe the nerve supply and blood supply of nasal septum.
(Sep 2002, 10 Marks)
Or
Write short note on blood supply and nerve supply of nasal septum.
(Aug 2012, 5 Marks)(Aug 2011, 5 Marks) (Aug 2008, 5 Marks)
Or
Describe formation, blood supply and nerve supply of nasal septum.
(Mar 2000, 18 Marks)
Ans. It is a median osteocartilaginous partition between two halves of nasal cavity.
On each side it is covered by mucous membrane and forms medial wall of both nasal cavities. It consists of three parts:
Formation of Nasal Septum
  1. Bony part: It is formed by:
    1. Vomer bone
    2. Perpendicular plate of ethmoid bone. Moreover its margins recieve contribution from nasal spine of frontal bone, rostrum of sphenoid and nasal crests of nasal, palatine and maxillary bones.
  2. 96Cartilaginous part: It is formed by:
    1. Septal cartilage
    2. Septal process of inferior nasal cartilage.
  3. Cuticular part: It is formed by fibro-fatty tissue covered by skin.
    Lower margin of nasal septum is known as columella.
    Nasal septum is rarely median. Its central part is deflected to one or other side. Deflection is produced by overgrowth of one or more parts.
    Overall, septum, consists of four borders, i.e. superior, inferior, anterior, posterior and two surfaces, i.e. right and left surfaces.
zoom view
Fig. 119: Formation of nasal septum
 
Blood Supply
Arterial Supply
  • Anteriosuperior part is supplied by anterior ethmoidal artery and posterior ethmoidal artery.
  • Anteroinferior part is supplied by superior labial branch of facial artery
zoom view
Fig. 120: Arterial supply of nasal septum
  • Posterosuperior part is supplied by sphenopalatine artery which is the main artery.
  • Posteroinferior part is supplied by branches of greater palatine artery.
  • Anteroinferior part or vestibule of septum consists of anastomoses between septal ramus of superior labial branch of facial artery, branch of sphenopalatine artery, greater palatine and of anterior ethmoidal artery. These form large capillary network known as Kiesselbach's plexus.
Venous Drainage
Veins forms a plexus which drains anteriorly into facial vein and posteriorly through sphenopalatine vein to pterygoid venous plexus.
 
Nerve Supply
  • General sensory nerve arising from trigeminal nerve are distributed to whole of septum.
    • Anterosuperior part of septum is supplied by internal nasal branch of anterior ethmoid nerve.
    • Anteroinferior part: It is supplied by anterior superior alveolar nerve
    • Posterosuperior part: It is supplied by medial posterior superior nasal branches of pterygopalatine ganglion
    • Posteroinferior part is supplied by nasopalatine branch of pterygopalatine ganglion. This is the main nerve.
  • Special sensory nerves or olfactory nerves which are confined to upper part or olfactory area.
zoom view
Fig. 121: Nerve supply of nasal septum
 
Applied Anatomy
  • Little's area over the nasal septum is common site of bleeding from the nose, i.e. epistaxis.
  • Deviation of nasal septum pathologically is responsible for repeated attacks of common cold, allergic rhinitis, sinusitis and needs surgical correction.
  • Artery of epistaxis is sphenopalatine artery.
Q.2. Enumerate openings in lateral wall of nose.
(Sep 2000, 4 Marks) (Apr 2010, 5 Marks)
97Ans.
  • Opening of nasolacrimal duct is seen at inferior meatus
  • Opening of frontal air sinus is seen in the anterior part of hiatus semilunaris
  • Opening of maxillary air sinus is seen in the posterior part of hiatus semilunaris
  • Opening of anterior ethmoidal air sinus is present at middle part of hiatus semilunaris
  • Opening of middle ethmoidal air sinus is present at upper margin of ethmoidal bulla.
  • Opening of posterior ethmoidal sinus is seen in the superior meatus
  • Opening of sphenoidal air sinus is seen in the sphenoethmoidal recess.
Q.3. Draw a labeled diagram to show features of lateral wall of nose.
(Dec 2003, 7 Marks)
Ans.
zoom view
Fig. 122: Features of lateral wall of nose
Q.4. Draw a labelled diagram of lateral wall of nose showing various openings.
(Dec 2010, 4 Marks) (Feb 2014, 4 Marks)
Or
Draw a labelled diagram to show the openings in lateral wall of nose.
(Feb 2004, 7 Marks)
Ans.
zoom view
Fig. 123: Openings in lateral wall of nose
Q.5. Write a short note on maxillary air sinus.
(Sep 2004, 5 Marks) (Mar 2000, 4 Marks)
(Mar 2007, 3 Marks) (Sep 2007, 4 Marks)
(Mar 2008, 4 Marks) (Apr 2007, 5 Marks)
(Feb 2013, 5 Marks)
Or
Write briefly on maxillary sinus.
(Jan 2012, 5 Marks)
Or
Enumerate paranasal air sinuses. Describe any one of them.
(Feb 2002, 10 Marks)
Or
Enumerate paranasal air sinuses. Describe maxillary sinus in detail. Development and applied anatomy.
(Mar 1998, 18 Marks)
Or
Enumerate paranasal air sinuses. Describe in detail maxillary air sinus.
(Sep 2012, 3 + 5 Marks)
Or
Enumerate paranasal air sinuses. Discuss anatomy of maxillary air sinus.
(Sep 2012, 3 + 5 Marks)
(Apr 2017, 10 Marks)
Or
State names of different paranasal air sinuses. Describe maxillary air sinus under following headings:
a. Situation
(Aug 2016, 10 Marks)
b. Boundaries
c. Communication
d. Nerve supply
e. Blood supply
Or
Name the paranasal air sinuses.
(Aug 2018, 1 Mark)
Ans.
 
Enumeration of Paranasal Air Sinuses
There are four paranasal air sinuses on each side and are named after the bones containing them:
  1. Frontal air sinus present in frontal bone.
  2. Maxillary air sinus present in maxilla.
  3. Sphenoidal air sinus present in sphenoid bone.
  4. Ethmoidal air sinus present in ethmoid bone:
    • Anterior ethmoidal air sinus.
    • Middle ethmoidal air sinus.
    • Posterior ethmoidal air sinus.
Clinically Sinuses are Divided into Two Main Groups
  • Anterior group: It consists of those sinuses which drains into middle meatus, i.e. frontal, anterior and middle ethmoidal and maxillary sinus.
  • Posterior group: It includes those sinuses which do not drain into middle meatus, i.e. posterior ethmoidal and sphenoidal air sinus.
98Maxillary Sinus
Maxillary air sinus is the first sinus to develop.
Situation
Maxillary sinus lies in the body of maxilla and is largest of all paranasal air sinuses.
Shape
It is pyramidal in shape with its base directed medially towards lateral wall of nose, and apex directed laterally in zygomatic process of maxilla.
Boundaries with Relations
  • Roof is formed by floor of orbit. Infraorbital nerve and artery traverse roof in bony canal.
  • Floor is formed by the alveolar process of maxilla and lies at about 1cm below level of floor of nose. This level corresponds to level of lower border of ala of nose. Floor is marked by several conical elevations produced by the roots of upper molar and premolar teeth. Canine tooth may project into anterolateral wall.
  • Base is formed by the lateral wall of nose. It posses opening or ostium of sinus in its upper part.
  • Apex extends into zygomatic process of maxilla.
  • Anterior wall is formed by the anterior surface of body of maxilla and is related to infraorbital plexus of nerves. In this wall runs the anterior superior alveolar nerve in curved bony canal.
  • Posterior wall is formed by the infratemporal surface of maxilla, separating sinus from infratemporal and pterygopalatine fossa. It is pierced by posterior superior alveolar nerves and vessels.
Communications
  • Maxillary sinus communicates with other sinuses through lateral nasal wall.
  • Opening through which the maxillary sinus communicates with the middle nasal meatus is termed as ostium maxillare. It is about 3 to 6 mm in diameter and is found in a recess called hiatus semilunaris.
  • Maxillary sinus may have septa that partially divide it into intercommunicating compartments with separate ostia may be found.
Openings
It opens into middle meatus of nose in lower part of hiatus semilunaris. A second opening is often present at the posterior end of hiatus.
In an isolated maxilla the opening of maxillary air sinus is large. However, in the intact skull the size of opening is reduced to 3 to 4 mm as it is overlapped by the following:
  • From above by uncinate process of ethmoid and descending part of lacrimal bone.
  • From below, by inferior nasal conchae.
  • From behind, by perpendicular plate of palatine bone.
 
Blood Supply
Arterial Supply
Maxillary air sinus is supplied by:
  • Facial artery
  • Infraorbital artery
  • Greater palatine artery
Venous Drainage
It drains into the facial vein and pterygoid plexus of veins.
Nerve Supply
Posterior superior alveolar nerve from maxillary nerve, anterior and middle superior alveolar nerves from infraorbital nerve.
Lymphatic Drainage
Lymph drains to the submandibular nodes.
zoom view
Fig. 124: Maxillary sinus
 
Applied Anatomy
  • Maxillary air sinus is commonly involved in the sinusitis. It may be infected from nose or from carious tooth. Drainage of sinus is difficult because its ostium lies at the higher level than its floor. Another factor is that cilia in lining mucosa are destroyed by chronic infection. Hence, the sinus is drained surgically by making an artificial opening near the floor.
  • Carcinoma of maxillary air sinus arises from mucosal lining. Symptoms depend on the direction of growth which are as follows:
    • Invasion of orbit causes proptosis or diplopia, i.e. blindness.
    • Invasion of floor may produce bulging or ulceration of palate.
    • Forward growth obliterates canine fossa and produces swelling on face.
    • Backward growth can involve palatine nerves and produce severe pain referred to upper teeth.
    • Growth in medial direction produces nasal obstruction, epistaxis and epiphora.
    • Growth in lateral direction produces swelling on the face and palpable mass inside labiogingival groove.
 
Development of Maxillary Sinus
  • Among all the sinuses, maxillary sinus is the first to develop.
  • 99Maxillary sinus starts developing at 16th week of the intrauterine life.
  • It appears as a shallow groove on the medial surface of maxilla during the fourth month of intrauterine life. It grows rapidly during 6 to 7 years of life.
  • When the crown-rump length (CRL) of an embryo is 32 mm, the CRL expands vertically in primordium of maxillary body.
  • At first, the horizontal shift of the palatal shelves occurs. These shelves then fuse with each other and also with the nasal septum. As a result of this the oral cavity gets separated from the nasal chambers.
  • All these changes result in the expansion of the lateral nasal wall, which starts folding.
  • As a result of this folding, three nasal conchae and three meatuses arise. Superior and inferior meatuses remain as shallow depressions along the lateral nasal wall and the middle meatus expands into the lateral nasal wall.
  • Maxillary sinus expands and modifies in form and it reaches its final height after the eruption of all permanent teeth.
zoom view
Fig. 125: Beginning of development of maxillary sinus
zoom view
Fig. 126: Folding of lateral nasal wall
Q.6. Describe paranasal air sinuses.
(Feb 2005, 10 Marks) (Sep 2000, 9 Marks)
Or
Write short note on paranasal sinuses (PNS).
(June 2010, 5 Marks) (Aug 2011, 5 Marks)(Aug 2012, 5 Marks)
Or
Describe the paranasal sinuses and their applied anatomy.
(Nov 2008, 15 Marks)
Ans. There are four paranasal air sinuses on each side and are named after the bones containing them:
  1. Frontal air sinus present in frontal bone.
  2. Maxillary air sinus present in maxilla.
  3. Sphenoidal air sinus present in sphenoid bone.
  4. Ethmoidal air sinus present in ethmoid bone
    • Anterior ethmoidal air sinus.
    • Middle ethmoidal air sinus.
    • Posterior ethmoidal air sinus.
Clinically, sinuses are divided into two main groups viz
  1. Anterior group: It consists of those sinuses, which drains into middle meatus, i.e. frontal, anterior and middle ethmoidal and maxillary sinus.
  2. Posterior group: It includes those sinuses which do not drain into middle meatus, i.e. posterior ethmoidal and sphenoidal air sinus.
 
Description of Paranasal Air Sinus
  • Frontal sinus: It lies in frontal bone deep to superciliary arches. It extends upward above medial end of eyebrow and backward into medial part of roof of orbit. It opens in of middle meatus of nose at anterior end of hiatus semilunaris through infundibulum or through frontonasal duct. The sinuses are better developed in males than females. They are well developed at 7th and 8th year of age but reaches its full size only at puberty.
    • Arterial supply: It is supplied by the supraorbital artery.
    • Venous drainage: It drains into supraorbital and superior ophthalmic vein.
    • Nerve supply: It is supplied by the supraorbital nerve.
    • Lymphatic drainage: Drains to submandibular nodes.
  • Maxillary air sinus: It is described briefly in Ans 5 of the same chapter.
  • Sphenoidal air sinus: Right and left sphenoidal sinuses lie within body of sphenoid bone. Each sinus opens into sphenoethmoidal recess of corresponding half of nasal cavity. They are separated by septum each sinus relates superiorly to optic chiasma and hypophysis cerebri and laterally to internal carotid artery and cavernous sinus.
    Arterial supply: It is supplied by:
    • Posterior ethmoidal artery
    • Internal carotid artery.
    Venous drainage: Into pterygoid venous plexus and cavernous sinus.100
    zoom view
    Fig. 127: Paranasal air sinuses
    zoom view
    Fig. 128: Formation of conchae and meatuses
    Nerve supply: It is supplied by:
    • Posterior ethmoidal nerve
    • Orbital branch of pterygopalatine ganglion.
    Lymphatic drainage: It drains to the retropharyngeal nodes.
  • Ethmoidal air sinus: They are numerous intercommunication spaces which lie in labyrinth of ethmoid bone. They get completed from above by orbital plate of frontal bone, from behind by sphenoidal conchae and orbital process of palatine bone, anteriorly by lacrimal bone. Basically, they are three in number, i.e.
    1. Anterior ethmoidal sinus: It is made up of 1 to 11 air cells. It opens in anterior part of hiatus semilunaris of nose. It is supplied by anterior ethmoidal nerve and vessels. Its lymphatics drain into submandibular nodes.
    2. Middle ethmoidal sinus: It is made up of 1 to 7 air cells. It opens in middle meatus of nose. It is supplied by anterior ethmoidal nerve and vessels and orbital braches of pterygopalatine ganglion. Lymphatics drains to submandibular nodes.
    3. Posterior ethmoidal sinus: It also consist of 1 to 7 air cells. It opens in superior meatus of nose. It is supplied by posterior ethmoidal nerve and vessels and orbital branch of pterygopalatine ganglion. Its lymphatics drain to retropharyngeal nodes.
 
Applied Anatomy
  • The maxillary air sinus is commonly involved in the sinusitis. It may be infected from nose or from carious tooth. Drainage of sinus is difficult because its ostium lies at the higher level then its floor. Another factor is that cilia in lining mucosa are destroyed by the chronic infection. Hence, the sinus is drained surgically by making an artificial opening near the floor.
    Carcinoma of maxillary air sinus arises from mucosal lining. Symptoms depend on the direction of growth which are as follows:
    • Invasion of orbit causes proptosis or diplopia, i.e. blindness.
    • Invasion of floor may produce bulging or ulceration of palate.
    • Forward growth obliterates canine fossa and produces swelling on face.
    • Backward growth can involve palatine nerves and produce severe pain referred to upper teeth.
    • Growth in medial direction produces nasal obstruction, epistaxis and epiphora.
    • Growth in lateral direction produces swelling on the face and palpable mass inside labiogingival groove.
  • Frontal sinusitis and ethmoiditis can cause edema of lids which is secondary to infection of sinuses.
  • Pain from ethmoidal air sinus is referred to the forehead since both of them are supplied by ophthalmic division of trigeminal nerve.
  • Pain of maxillary sinusitis can be referred to maxillary teeth as well as infraorbital skin as all of them are supplied by the maxillary nerve.
Q.7. Write a short note on pterygopalatine ganglion.
(Mar 1998, 4 Marks)
Ans. This is the largest parasympathetic peripheral ganglion. It serves as relay station for secretomotor fibers to lacrimal gland, paranasal sinuses, palate and pharynx. Topographically, it is related to maxillary nerve, but functionally it is connected to facial nerve via its greater petrosal branch.
 
Connections
  • Parasympathetic or motor root:
    • It is formed by the nerve of pterygoid canal.
    • Preganglionic fibers arises from neurons present near superior salivatory nucleus and lacrimatory nuclei and pass via nervus intermedius, facial nerve, geniculate ganglion, greater petrosal nerve and nerve to pterygoid canal to reach the pterygopalatine ganglion and relay.
    • Postganglionic fibers arise in pterygopalatine ganglion and supply secretomotor nerves to lacrimal gland, 101mucous glands of nose, paranasal air sinuses, palate and nasopharynx.
  • Sympathetic root
    • It is derived from nerve of pterygoid canal.
    • Postganglionic fibers arise superior cervical sympathetic ganglion which pass via internal carotid plexus, deep petrosal nerve and nerve to pterygoid canal to reach ganglion. Fibers does not relay and supply to vasomotor nerves to mucous membrane of nose, paranasal sinus, palate and nasopharynx.
  • Sensory roots are derived from maxillary nerve. Fibers of sensory root does not relay in ganglion and they emerge as various branches, i.e. orbital branch, palatine branches, nasal branches, pharyngeal branch and lacrimal branch.
 
Branches of Pterygopalatine Ganglion
Branches of ganglion are actually branches of maxillary nerve. The branches are:
  • Orbital branches: They pass through inferior orbital fissure, periosteum of orbit and orbitalis
  • Palatine branches: They supply to hard palate, lateral wall of nose, lesser palatine nerve supply to soft palate and tonsils.
  • Nasal branches: The lateral posterior superior nasal nerve supply to posterior part of superior and middle constrictor.
    Medial posterior superior nerve supply to posterior part of roof of nose and nasal septum the largest of these nerves is known as nasopalatine nerve which descends to anterior part of hard palate.
  • Pharyngeal branches: It supplies to the part of nasopharynx behind auditory tube.
  • Lacrimal branch: Postganglionic fibers pass back in maxillary nerve to leave it via zygomatic nerve and zygomaticotemporal branch to supply secretomotor fibers to lacrimal gland.
zoom view
Fig. 129: Connections and branches of pterygopalatine ganglion
Q.8. Name the paranasal air sinuses.
(Feb 2003, 3 Marks) (Apr 2010, 5 Marks)
Ans. There are four paranasal air sinuses on each side and are named after the bones containing them:
  1. Frontal air sinus present in frontal bone.
  2. Maxillary air sinus present in maxilla.
  3. Sphenoidal air sinus present in sphenoid bone.
  4. Ethmoidal air sinus present in ethmoid bone:
    • Anterior ethmoidal air sinus.
    • Middle ethmoidal air sinus.
    • Posterior ethmoidal air sinus.
Clinically sinuses are divided into two main groups viz:
  1. Anterior group: It consists of those sinuses which drains into middle meatus, i.e. frontal, anterior and middle ethmoidal and maxillary sinus.
  2. Posterior group: It includes those sinuses which do not drain into middle meatus, i.e. posterior ethmoidal and sphenoidal air sinus.
Q.9. Enumerate the paranasal air sinus, give its functions and openings in nasal cavity.
(Mar 2006, 5 Marks)
Ans. For enumeration refer to Ans 8 of the same chapter.
 
Function
  • Paranasal air sinus helps in both the functions olfactory as well as respiratory.
  • It causes humidification and warming of inspired air and contribution to the olfactory.
  • It is possible that if air is arrested in the sinus for a certain time, it quickly reaches the body temperature thus protects the internal structure, particularly the brain against exposure of cold air.
  • Other contribution is in the response of voice, lightening of skull weight, enhancement of the faciocranial resistance to mechanical shock, and the production of bactericidal lysozyme to nasal cavity.
 
Openings in Nasal Cavity
  • Opening of nasolacrimal duct is seen in the inferior meatus.
  • Opening of frontal air sinus is seen in the anterior part of hiatus semilunaris
  • Opening of maxillary air sinus is seen in the posterior part of hiatus semilunaris
  • Opening of anterior ethmoidal air sinus is present at middle part of hiatus semilunaris
  • Opening of middle ethmoidal air sinus is present at upper margin of ethmoidal bulla.
  • Opening of posterior ethmoidal sinus is the seen in the superior meatus.
  • Opening of sphenoidal air sinus is seen in the sphenoethmoidal recess.
Q.10. Write a short note on openings in the lateral wall of nasal cavity.
(Mar 2006, 5 Marks)
Ans.
  • Opening of nasolacrimal duct is seen in the inferior meatus at junction of anterior one- third and posterior two-third. The opening is guarded by lacrimal fold or Hasner's valve.
  • Opening of frontal air sinus is seen in the anterior part of hiatus semilunaris.
  • Opening of maxillary air sinus is seen in the posterior part of hiatus semilunaris. It is often represented by the two openings.
  • Opening of anterior ethmoidal air sinus is present at middle part of hiatus semilunaris. It is mainly present behind the opening of frontal air sinus.
  • 102Opening of middle ethmoidal air sinus is present at upper margin of ethmoidal bulla.
  • Opening of posterior ethmoidal sinus is seen in the superior meatus.
  • Opening of sphenoidal air sinus is seen in the sphenoethmoidal recess which is the triangular fossa just above superior concha.
Q11. Enumerate the paranasal air sinuses. What are the functions of these sinuses? Name the nerves supplying them. Add a note on their applied anatomy.
(Sep 2006, 8 Marks)
Ans. For enumeration refer to Ans 8 of the same chapter. For function refer to Ans 9 of the same chapter. For applied anatomy refer to Ans 6 of same chapter.
Name of the paranasal air sinus
Nerve supplying
Frontal sinus
Supraorbital nerve
Maxillary sinus
Posterior superior alveolar nerve from maxillary nerve, anterior and middle superior alveolar nerves from infraorbital nerve
Sphenoidal sinus
Posterior ethmoidal nerve and orbital branches of pterygopalatine ganglion
Ethmoidal sinus
  • Anterior ethmoidal sinus
  • Midlle ethmoidal sinus
  • Posterior ethmoidal sinus
  • Anterior ethmoidal nerve
  • Anterior ethmoidal nerve and orbital branches of pterygopalatine ganglion
  • Posterior ethmoidal nerve and orbital branches of pterygopalatine ganglion
Q.12. Write a note on lateral wall of the nose.
(Mar 2007, 4 Marks)
Or
Write in short on lateral wall of the nose.
(Aug 2012, 5 Marks) (Dec 2010, 5 Marks)
Or
Write short note on lateral wall of nose.
(Aug 2018, 5 marks)
Ans. Lateral wall of the nose is irregular and consists of three shelf like bony projections called conchae.
  • Conchae increases the surface area of the nose for effective conditioning of the inspired air.
 
Lateral Wall Leads to Separation of the Nose
  • From orbit above with ethmoidal air sinus and intervening maxillary sinus below
  • In front by lacrimal groove and nasolacrimal canal.
 
Subdivision of Lateral Wall of Nose
Lateral wall of nose is subdivided into three parts i.e.
  1. A small depressed area in the anterior part is known as vestibule. Vestibule is lined by modified skin containing short, stiff, curved hair called “Vibrissae”.
  2. Middle part is called as the atrium of the middle meatus.
  3. Posterior part consists of conchae and the spaces separating conchae are known as meatus.
Conchae and Meatuses form the Main Features of the Lateral Wall
Conchae (also called turbinates) are the curved bony actions directed downwards and medially. Below and lateral to each concha is a corresponding meatus. From above downwards the conchae are superior, middle, and inferior nasal conchae. Sometimes a 4th concha, the concha suprema is also present.
Skeleton of the Lateral Wall
It is partly bony, partly cartilagenous and partly made up of soft tissues.
  • Bony part: It is formed by
    • Nasal
    • Frontal process of maxilla
    • Lacrimal
    • Labryinth of ethamoid with superior and middle conchae.
    • Inferior nasal concha made of spongy bone only.
    • Perpendicular plate of the palatine bone together with orbital and sphenoidal processes.
    • Medial pterygoid plate.
  • Cartilaginous part is formed by:
    • Superior nasal cartilage
    • Inferior nasal cartilage
    • 3 or 4 small cartilages of ala.
  • Cuticular lower part is formed by fibrofatty tissue covered by skin.
Conchae
  • Superior and middle nasal conchae are the projections from the medial surface of the ethmoidal labyrinth.
  • Inferior concha is an independent bone.
  • The superior concha is smallest and inferior concha is largest in size.
Meatuses
Meatuses are the passages (recesses) beneath the overhanging conchae. They are visualized once conchae are removed.
  • Inferior meatus is the largest and lies underneath the inferior nasal concha.
  • Middle meatus lies underneath the middle concha. It presents following features:
    • Ethmoidal bulla (bulla ethmoidalis), a round elevation produced by the underlying middle ethmoidal sinuses.
    • Hiatus semilunaris, a deep semicircular sulcus below the bulla ethmoidalis.
    • Infundibulum, a short passage at the anterior end of middle meatus.
  • Superior meatus is the smallest and lies below the superior concha.
A triangular depression, above and behind the superior concha is known as the sphenoethmoidal recess.103
zoom view
Fig. 130: Formation of lateral wall of nose
Openings of Lateral Wall of the Nose
  • Opening of nasolacrimal duct is seen in the inferior meatus.
  • Opening of frontal air sinus is seen in the anterior part of hiatus semilunaris.
  • Opening of maxillary air sinus is seen in the posterior part of hiatus semilunaris
  • Opening of anterior ethmoidal air sinus is present at middle part of hiatus semilunaris.
  • Opening of middle ethmoidal air sinus is present at upper margin of ethmoidal bulla.
  • Opening of posterior ethmoidal sinus is seen in superior meatus.
  • Opening of sphenoidal air sinus is seen in the sphenoethmoidal recess.
Arterial Supply
  • Anterosuperior quadrant by anterior ethmoidal artery
  • Anteroinferior quadrant by branches from facial and greater palatine arteries.
  • Posteroinferior quadrant by few branches of sphenopalatine artery.
  • Posterionferior quadrant by branches from greater palatine artery.
Venous Drainage
Venous form a plexus which drains:
  • Anterioly into facial vein
  • Posterioly into pharyngeal plexuses of vein
  • Middle part by pterygoid plexus of vein.
Nerve Supply
  1. General sensory nerves: They are derived from the branches of trigeminal nerve which supplies to the lateral wall.
    zoom view
    Fig. 131: Arterial supply of lateral wall of nose
    1. Anterosuperior quadrant by anterior ethmoidal nerve branch of ophthalmic nerve.
    2. Anteroinferior quadrant by anterior superior alveolar nerve branch of infraorbital, continuation of maxillary nerve.
    3. Posterosuperior quadrant by lateral posterior superior nasal branches from pterygopalatine ganglion.
    4. Posteroinferior quadrant by anterior palatine branch of pterygopalatine ganglion.
  2. Special sensory nerves: These are the olfactory nerves which are distributed to upper part of lateral wall below cribriform plate of ethmoid bone upto superior concha.104
zoom view
Fig. 132: Nerve supply of lateral wall of nose
Lymphatic Drainage
  • From anterior half to submandibular nodes
  • From posterior half to retropharyngeal and upper deep cervical nodes.
Q.13. Write short note on pterygopalatine fossa.
(Dec 2009, 5 Marks)
Ans. It is also known as sphenopalatine fossa or ganglion of hay fever.
Pterygopalatine fossa is a small pyramidal space which is situated deep below the apex of the orbit.
 
Boundaries
It is bounded:
  • Anteriorly by superomedial part of the posterior surface of the maxilla.
  • Posteriorly by root of the pterygoid process and adjoining part of the anterior surface of greater wing of the sphenoid.
  • Medially by upper part of the perpendicular plate of the palatine bone. Orbital and sphenoidal processes of the bone are also involved.
  • Laterally the fossa opens into infratemporal fossa through the pterygomaxillary fissure.
  • Superiorly by the undersurface of body of sphenoid.
  • Inferiorly it is closed by the pyramidal process of palatine bone in the angle between the maxilla and pterygoid process.
 
Communications
It is communicated:
  • Anteriorly by the orbit through medial end of the inferior orbital fissure.
  • Posteriorly with the middle cranial fossa via foramen rotundum; with foramen lacerum via pterygoid canal; and with pharynx via palatovaginal canal.
  • Medially with nose via sphenopalatine foramen.
  • Laterally with infratemporal fossa via pterygomaxillary fissure.
  • Inferiorly with the oral cavity via greater and lesser palatine canals.
 
Contents
  • Third part of maxillary artery and its branches which have same name as branches of pterygopalatine ganglia and accompany them all.
  • Maxillary nerve and its two branches, i.e. zygomatic and posterior superior alveolar.
  • Pterygopalatine ganglion and its numerous branches which consists of fibers of maxillary nerve mixed with autonomic nerves.
zoom view
Fig. 133: Pterygopalatine fossa along with its communications
Q.14. Write short note on openings of paranasal sinuses.
(Sep 2017, 2 Marks)
Ans. Following are the openings of paranasal sinuses:
  • Opening of frontal air sinus is seen in the anterior part of hiatus semilunaris.
  • Opening of maxillary air sinus is seen in the posterior part of hiatus semilunaris. It is often represented by the two openings.
  • Opening of anterior ethmoidal air sinus is present at middle part of hiatus semilunaris. It is mainly present behind the opening of frontal air sinus.
  • Opening of middle ethmoidal air sinus is present at upper margin of ethmoidal bulla.
  • Opening of posterior ethmoidal sinus is seen in the superior meatus.
  • Opening of sphenoidal air sinus is seen in the sphenoethmoidal recess which is the triangular fossa just above superior concha.
Q.15. Enumerate arterial supply of nasal septum.
(Apr 2018, 2 Marks)
Ans. Following is the arterial supply of nasal septum:
  • Anteriosuperior part is supplied by anterior ethmoidal artery and posterior ethmoidal artery.
  • Anteroinferior part is supplied by superior labial branch of facial artery.
  • 105Posterosuperior part is supplied by sphenopalatine artery which is the main artery.
  • Posteroinferior part is supplied by the branches of greater palatine artery.
 
16. LARYNX
Q.1. Enumerate the cartilages of larynx.
(Sep 2002, 2 Marks)
Or
Write briefly on cartilages of larynx
(Nov 2008, 5 Marks)
Ans. Larynx is a organ for phonation. Larynx lies at anterior midline of neck extending from root of tongue to trachea. In adult male it lies in front of C3, C4, C5 and C6 but in children or in adult female it lies at the higher level.
 
Laryngeal Cartilages
zoom view
Fig. 134: Laryngeal cartilages
Larynx consists of six cartilages out of which three are unpaired and three are paired.
zoom view
Fig. 135: Interior aspect of laryngeal cartilages
Unpaired Cartilage
  • Thyroid cartilage (sheid like)
  • Cricoid cartilage (ring like)
  • Epiglottic cartilage (leaf like).
Paired Cartilage
  • Arytenoid cartilage (cup shaped)
  • Corniculate cartilage (horn shaped)
  • Cuniform cartilage (wedge shaped).
 
Unpaired Cartilage
Thyroid Cartilage
  • It is V-shape cartilage.
  • Thyroid cartilage consists of right and left laminae.
  • Each lamina is roughly quadrilateral, laminae are placed obliquely relative to midline, their posterior borders are far apart while anterior borders approach each other which is 90° in males and 120° in females.
  • Lower part of anterior border of right and left laminae fuse and form a median projection known as laryngeal prominence.
  • Upper parts of both the anterior borders do not meet and are separated by the thyroid notch.
  • Posterior borders are free and are extended upwards and downwards and are named as superior and inferior cornua (horns).
  • Superior cornua is connected with the greater cornua of the hyoid bone by lateral thyrohyoid ligament, while inferior cornua articulate with the cricoid cartilage to form the cricothyroid joint.
  • Inferior border of the thyroid cartilage concavo-convex, i.e. convex in front and concave behind.
  • In the median plane it is connected to the cricoid cartilage by the conus elasticus.
  • Outer surface of each lamina is marked by an oblique line which extends from the superior thyroid tubercle in front of the root of superior cornua to the inferior thyroid tubercle behind middle of the inferior border.
Cricoid Cartilage
  • It is of ring shape.
  • This cartilage encircles the larynx below the thyroid cartilage and makes, foundation of larynx.
  • This cartilage is thick and strong as compared to thyroid cartilage.
  • Its anterior part is narrow and is called as arch, while its posterior part is broad known as lamina.
  • Lamina projects upwards behind thyroid cartilage, it articulate superiorly with arytenoids cartilages.
  • Inferior cornua of thyroid cartilage articulates with side of cricoid cartilage at the junction of arch and lamina.
Epiglottic Cartilage
  • It is of leaf shape placed in anterior wall of upper part of larynx.
  • 106Its upper end is broad and free, it projects upward behind hyoid bone as well as tongue.
  • Lower end or thyroepiglottic ligament is pointed and is attached to upper part of angle between the two laminae of thyroid cartilage.
 
Paired Cartilage
Arytenoid Cartilage
  • They are two small pyramid shape cartilage which lie over upper border of lamina of cricoids cartilage.
  • Apex of arytenoid cartilage is curved posteromedially and articulates with corniculate cartilage.
  • Base is concave and articulates with lateral part of upper border of cricoids lamina. This prolong anteriorly to form vocal process and laterally to form muscular process.
  • Surfaces of cartilage are anterolateral, medial and posterior.
Corniculate Cartilage
  • These are two small conical nodules which articulate with apex of arytenoid cartilage which are directed posteromedially.
  • These conical lie in posterior part of aryepiglottic folds.
Cuniform Cartilage
These are two small rod shaped pieces of cartilage placed in aryepiglottic fold which are just ventral to corniculate cartilages.
Q.2. Write short note on nerve supply of larynx
(Apr 2008, 5 Marks)
Ans.
  1. Motor nerve: All intrinsic muscles of larynx are supplied by recurrent laryngeal nerve except cricothyroid which is supplied by the external laryngeal nerve.
  2. Sensory nerve: The internal laryngeal nerve supply mucous membrane upto level of vocal folds. Recurrent laryngeal nerve supply it below the level of vocal folds.
Q.3. Write short note on vocal folds.
(Sep 2011, 5 Marks)
Ans. Within the laryngeal cavity, the mucous membrane presents with two folds that extend on each side posteroanteriorly from the arytenoid cartilages to the thyroid cartilage.
These are true and false vocal cords.
Vocal folds are also known as true vocal cords:
  • These folds are produced by the underlying vocal ligaments and vocalis muscle and lie below the false vocal cords.
  • Space between the right and left vocal folds is called as ‘rima glottidis’
  • Vocal cords act as entry valves. They prevent entry of all substances through rima glottis except air.
  • Speech (phonation) is produced by vibrations of the vocal cords. Greater the amplitude of vibration, the louder is the sound. Pitch of sound is controlled by the frequency of the vibrations.
  • Since males have longer vocal cords than females, they have louder but low pitched voices than females.
Q.4. Write short note on thyroid cartilage.
(Sep 2011, 5 Marks)
Ans.
  • Thyroid cartilage is V-shaped in its cross section.
  • Cartilage consists of right and left laminae. Shape of each lamina is roughly quadrilateral.
  • Laminae are placed obliquely relative to the midline and their posterior borders are far apart, but the anterior borders approach each other at an angle that is about 90° in the male and about l20° in the female.
  • Lower part of anterior borders of right and left laminae combine and form a median projection known as laryngeal prominence.
  • Upper parts of both the anterior borders do not meet and are separated by the thyroid notch.
  • Posterior borders are free and are extended upwards and downwards and are named as superior and inferior cornua (horns).
  • Superior cornua is connected with the greater cornua of the hyoid bone by lateral thyrohyoid ligament.
  • Inferior cornua articulate with the cricoid cartilage to form the cricothyroid joint.
  • Inferior border of the thyroid cartilage concavoconvex, i.e. convex in front and concave behind.
  • In the median plane it is connected to the cricoid cartilage by the conus elasticus.
  • Outer surface of each lamina is marked by an oblique line which extends from the superior thyroid tubercle in front of root of superior cornua to the inferior thyroid tubercle behind middle of inferior border.
  • Thyrohyoid, sternothyroid and thyropharyngeus are part of inferior constrictor of pharynx is attached to oblique line.
zoom view
Fig. 136: Anterior and posterior view of thyroid and cricoid cartilage
 
Attachments
  • Lower border as well as inferior cornua provides insertion to triangular cricothyroid.
  • At posterior border connecting the superior and inferior cornua is insertion of palatopharyngeus, salpingopharyngeus and stylopharyngeus.
  • Over the inner aspect following are attached:
    • Median thyroepiglottic ligament
    • Thyroepiglottic muscle over each side
    • 107Vestibular fold over each side
    • Vocal fold over each side
    • Thyroarytenoid
    • Vocalis muscle over each side.
Q.5. Write short note on cricoid cartilage.
(Sep 2011, 5 Marks)
Ans.
  • Cricoid cartilage has a shape of signet ring.
  • It encircle larynx below thyroid cartilage.
  • The cartilage is thick and strong as compared to thyroid cartilage.
  • It consists of narrow anterior part known as arch and broad posterior part known as lamina.
  • Projection of lamina is upwards behind the thyroid cartilage and it articulate superiorly with arytenoid cartilage.
  • Inferior cornua of thyroid cartilage articulate with side of cricoid cartilage at junction of arch and lamina.
For diagram of cricoid cartilage refer to Ans 4 of same chapter.
 
Attachment of Cricoid Cartilage
  • Anterior part provides origin to cricothyroid muscle.
  • Anterolateral part provide origin to lateral cricoarytenoid muscle
  • Lamina of cricoid cartilage give origin to posterior cricoarytenoid muscle
  • Cricothyroid and quadrate membranes are also attached.
Q.6. Write in brief about piriform fossa.
(Sep 2015, 5 Marks)
Or
Write short note on piriform fossa and clinical significance.
(Sep 2015, 5 Marks)
Ans. Piriform fossa is deep recess broad above and narrow below in the anterior part of lateral wall of the laryngopharynx on each side of the laryngeal inlet. These recesses are produced due to bulging of larynx into laryngopharynx. It is present one on each side of inlet of larynx.
 
Boundaries
  • Medial: Aryepiglottic fold and quadrangular membrane of larynx.
  • Lateral: Mucous membrane covering the medial surface of the lamina of thyroid cartilage and thyrohyoid membrane.
  • The internal laryngeal nerve and superior laryngeal vessels pierce the thyrohyoid membrane and traverse underneath the mucous membrane of the floor of the fossa to reach the medial wall.
  • Above: Piriform fossa is separated from epiglottic vallecula by lateral glossoepiglottic fold.
  • Inferior: It continues as esophagus.
 
Clinical Importance
  • Anatomically it is a hidden area. Any malignancy in this area will initially cause fewer symptoms and has a tendency to present late symptoms.
  • This area is rich in lymphatics. These lymphatics drain into the upper deep cervical group of nodes. Malignancy in this area has a tendency for distant metastasis.
  • Foreign bodies such as fish bones commonly gets lodged in piriform fossa. These bones scratch mucosa and person feel foreign body sensation because of dull visceral pain.
  • Piriform fossa is also known as smuggler's fossa as it is used to smuggle precious diamonds and stones.
  • Pooling of saliva occurs in pyriform fossa if there is any obstruction in the food passage (Jackson's sign).
zoom view
Fig. 137: Piriform fossa
Q.7. Name the muscles of larynx.
(Aug 2016, 2 Marks)
Ans. Following are the muscles of larynx:
  • Extrinsic muscles
    • Palatopharyngeus
    • Salpingopharyngeus
    • Stylopharyngeus
    • Thyrohyoid
    • Sternothyroid
  • Intrinsic muscles
    • Cricothyroid
    • Posterior cricoarytenoid triangular
    • Lateral cricoarytenoid
    • Transverse arytenoids
    • Oblique arytenoids and aryepiglottic
    • Thyroarytenoid and thyroepiglottic
    • Vocalis.
 
17. THE TONGUE
Q.1. Enumerate the sensory innervations of tongue.
(Feb 2002, 2 Marks)
Or
Describe position, parts, blood supply, and innervations of tongue.
(Feb 2002, 10 Marks)
Or
108Describe muscles of tongue.
(Apr 2010, 5 Marks)
Or
Describe the tongue and give its nerve supply.
(Sep 2013, 10 Marks)
Or
Write short note on nerve supply and lymphatic drainage of tongue.
(Aug 2012, 5 Marks)
Or
Write short note on blood supply and nerve supply of tongue.
(May/June 2009, 5 Marks) (Nov 2008, 5 Marks)
Or
Write short note on sensory innervations of tongue.
(July 2016, 5 Marks) (Apr 2007, 5 Marks)
Or
Write a short note on innervation of tongue.
(Sep 2006, 5 Marks)
Or
Write short note on nerve supply of tongue.
(Sep 2007, 3 Marks) (Apr 2015, 3 Marks)
(Jan 2018, 5 Marks)
Or
Write a short note on lymphatic drainage of tongue.
(Oct 2007, 5 Marks) (Jan 2012, 5 Marks)
(May 2017, 3 Marks)
(June 2010, 5 Marks)
Or
Write briefly lymphatic drainage of tongue and its applied aspect.
(Dec 2010, 5 Marks)
Or
Describe tongue in detail and give its applied aspect.
(Nov 2009, 10 Marks)
Or
Describe the tongue in detail.
(Jan 2012, 15 Marks)
Or
Write very short answer on lymphatic drainage of tongue.
(Apr 2018, 2 Marks)
Or
Write very short answer on extrinsic muscles of tongue.
(Aug 2018, 2 Marks)
Ans. Position of Tongue
Tongue is a muscular organ situated in floor of the mouth.
 
Parts of Tongue
Tongue consists of following parts:
  • Root: It is attached to styloid process and soft palate above and to mandible and hyoid bone below. In between the mandible and hyoid bones it is related to geniohyoid and mylohyoid muscles.
  • Tip: Tip of the tongue forms anterior free end which rest, lie behind maxillary incisor teeth.
  • Body: It is divided into two parts:
    1. Dorsum:
      • This is convex in all the directions. It is divided into oral and pharyngeal parts by V-shaped sulcus terminalis.
      • Oral part is also known as anterior two-third of tongue.
      • Oral part presents a median furrow, representing bilateral origin of tongue as well as large number of papillae
      • Pharyngeal part or posterior one third by a V shaped groove known as sulcus terminalis. Two limbs of V meet at median pit called as foramen caecum. Both the limbs run laterally and forwards upto palatoglossal arches.
      • The third part is small posteriomost part.
    2. An inferior surface: This is confined to oral part only. Mucous membrane lining this surface is thin, smooth and purpulish. It is reflected onto the floor of the mouth. The under aspect of the tongue presents the following features:
      • Frenulum linguae, a median-fold of mucus membrane connecting the tongue to the floor of the mouth.
      • Deep lingual veins, may be seen through mucous membrane on either side of frenulum linguae (the lingual nerve and lingual artery are medial to the vein but not visible).
      • Plica fimbriata, a fringed fimbriated fold of mucous membrane lateral to the lingual vein directed forwards and medially towards the tip of the tongue.
zoom view
Fig. 138: Dorsum of tongue
zoom view
Fig. 139: Inferior surface of tongue
 
109Muscles of the Tongue
Middle fibrous septum divides the tongue into right and left halves. Each half contains four intrinsic and four extrinsic muscles.
Intrinsic Muscles
These muscles occupy upper part of the tongue and attached to submucous fibrous layer and median fibrous septum.
Intrinsic muscle
Location
Actions
Superior longitudinal
Beneath the mucus membrane
  • Shortens the tongue
  • Makes dorsum concave
Inferior longitudinal
It lies close to inferior surface between genioglossus and hyoglossus
  • Shortens the tongue
  • Makes dorsum convex
Transverse
It extends from median septum to margins
  • Makes tongue narrow and elongated
Vertical
It is found at borders of anterior part of tongue
  • Makes tongue broad and flattened
zoom view
Fig. 140: Intrinsic muscles of tongue
zoom view
Fig. 141: Coronal section of tongue
Extrinsic Muscles
Muscle
Origin
Insertion
Action
Palatoglossus
From oral surface of palatine aponeurosis
Descends inside the palatoglossal arch to side of tongue at the junction of oral and pharyngeal parts
Pulls the root of tongue, approximate palatoglossal arches and closes oropharyngeal isthmus
Hyoglossus
From whole length of greater cornua as well as lateral part of hyoid bone
At the side of tongue in between styloglossus and inferior longitudinal muscle
Depresses tongue, make dorsum convex, retracts protruded tongue
Styloglossus
From tip and part of anterior surface of styloid process
Side of tongue
Pull tongue upward and backward i.e. it retract the tongue
Genioglossus
From upper genial tubercle of mandible
  • Upper fibers into the tip of tongue
  • Middle fibers into dorsum
  • Lower fibers into hyoid bone
  • Depresses the tongue
  • Retracts the tongue
  • Pull posterior part of tongue forward and protrude tongue forward. This is also known as life saving muscle
zoom view
Fig. 142: Extrinsic muscles of tongue
 
Blood Supply
Arterial Supply of Tongue
It is chiefly supplied by tortuous lingual artery which is branch of external carotid artery. Root of tongue is supplied by the tonsillar artery a branch of facial artery and ascending pharyngeal branch of external carotid artery.110
zoom view
Fig. 143: Nerve supply of tongue
Venous Drainage
  • Deep lingual vein is largest and principal vein of tongue. It is visible on inferior surface of tongue.
  • Arrangement of veins of tongue is variable. Two venae comitants accompany lingual artery and one venae comitant the hypoglossal nerve.
  • These veins unite at posterior border of hyoglossus to form lingual vein which ends in internal jugular vein.
 
Lymphatic Drainage
  • Tip of tongue drains bilaterally to submental nodes.
  • Right and left halves of remaining part of anterior 2/3 of the tongue drains unilaterally to submandibular nodes. Few central lymphatics drain bilaterally to deep cervical lymph nodes.
  • Posterior 1/3 and posteriomost part drains bilaterally to upper deep cervical lymph nodes including juglodigastric nodes.
  • Whole lymph finally drains to jugulo-omohyoid lymph nodes.
 
Nerve Supply
  • Motor supply: All extrinsic and intrinsic muscles except palatoglossus are supplied by the hypoglossal nerve. Palatoglossus is supplied by the cranial root of accessory nerve through pharyngeal plexus.
  • Sensory innervations:
    • Lingual nerve is general nerve of sensation and chorda tympani is nerve for taste for anterior 2/3 of tongue except vallate papillae.
    • For posterior 1/3 and circumvallate papillae glossophar-yngeal nerve is nerve for both general and taste sensation.
    • Posterior most part is supplied by vagus nerve through internal laryngeal branch.
zoom view
Fig. 144: Arterial supply of tongue
 
Applied Aspect
  • Carcinoma of the tongue is common. This is better treated by radiotherapy than by surgery. But since facilities for irradiation are not always available, the affected side of the tongue is removed surgically. All the deep cervical lymph nodes are also removed because recurrence of malignant disease occurs in lymph nodes. Carcinoma of the posterior one-third of the tongue is more dangerous due to bilateral lymphatic spread.
  • Sorbitrate is taken sublingually for immediate relief from angina pectoris. It is absorbed due to rich blood supply of tongue and by passing of portal circulation.111
zoom view
Fig. 145: Lymphatic drainage of tongue
  • Genioglossus is known as safety muscle of tongue, this is because as this muscle get paralyzed, tongue will fall back to oropharynx and block passage of air. During anesthesia, tongue should be pulled forward to clear the air passage.
  • Genioglossus is the only muscle which protrudes forward. It is used for testing integrity of hypoglossal nerve. If hypoglossal nerve over right side gets paralyzed, tongue on protrusion deviate to right side. Normal left genioglossus will pull base to left side and apex will get pushed to right side.
  • Glossitis is usually a part of generalized ulceration of the mouth cavity (stomatitis). In certain anemias tongue becomes bald due to atrophy of the filiform papillae.
  • Presence of a rich network of lymphatics and of loose areolar tissue in the substance of the tongue is responsible for enormous swelling of the tongue in acute glossitis. The tongue fills up the mouth cavity and then protrudes out of it.
  • Undersurface of the tongue is a good site for observation of jaundice.
  • In unconscious patients tongue may fall back and obstruct air passages. This can be prevented either by lying the patient on one side with head down or by keeping the tongue pulled out mechanically.
  • In patients with grand mal epilepsy tongue is commonly bitten between the teeth during the attack.
Q.2. Describe the tongue under the following headings:
(Sep 2007)
a. Gross anatomy
(3 Marks)
b. Histology
(2 Marks)
c. Development and anomalies
(3 Marks)
Ans. Gross Anatomy
Tongue consists of root, a tip, and a body which is divided into a curved upper surface of dorsum and an inferior surface.
Dorsum of tongue is divided into oral and pharyngeal parts by sulcus terminalis and the inferior surface is confined to the oral part.
Tip of the tongue forms the anterior free end.
Dorsum of the tongue is convex from all aspects. It is divided into an
  1. An oral part, i.e. anterior two-third
  2. A pharyngeal part, i.e. posterior one-third part
  3. Posteriomost part.
 
Oral or Papillary Part
It lies on the floor of the mouth. Its margins are free and in contact with the gums and teeth. In front of the palatoglossal arch, each margin consists of 4 to 5 vertical folds known as foliate papillae. Superior surface of the oral part consists of median furrow and is covered with papillae which make it rough. The inferior surface is covered with a smooth mucous membrane, which shows a median fold known as frenulum linguae. On either side of the frenulum there is a prominence produced by the deep lingual veins. More laterally there is a fold known as plica fimbriata which is directed forwards and medially towards the tip of the tongue.
 
Pharyngeal (lymphoid) Part of the Tongue
It lies behind the palatoglossal arches and sulcus terminalis. Posterior surface of this part of tongue forms the anterior wall of oropharynx and is also known as base of tongue. Mucous membrane has no papillae, but consists of many lymphoid follicles which collectively constitute lingual tonsil. Mucous glands are also present.
 
112Posteriomost Part
Posteriomost part of the tongue is connected to the epiglottis by three folds of mucous membrane which are known as median glossoepiglottic fold and the right and left lateral glossoepiglottic folds. On each side of the median fold there is a depression known as vallecula. The lateral folds separate vallecula from the piriform fossa.
zoom view
Fig. 146: Dorsum of tongue
zoom view
Fig. 147: Inferior surface of tongue
 
Histology
For histology of tongue refer to Ans 22 in SECTION HISTOLOGY.
 
Development of Tongue
Epithelium
  • Anterior two-third: It develops from two lingual swellings which arise from first branchial arch. So it is supplied by lingual nerve of first arch and chorda tympani of second arch.
  • Posterior one-third: It develops from cranial part of hypobranchial eminence, i.e. from third arch. So it is supplied by the glossopharyngeal nerve.
  • Posteriormost part develops from fourth arch. It is supplied by the vagus nerve.
Muscles
They develop by occipital myotomes which are supplied by the hypoglossal nerve.
Connective Tissue
It develops from local mesenchyme.
 
Anomalies of Tongue
Following are the anomalies of tongue:
  • Aglossia: Absence of tongue
  • Ankyloglossia: Tongue is adherent to palate in ankyloglossia superior and tongue is adherent to floor of mouth in ankyloglossia inferior.
  • Bifid tongue: In this, there is cleavage of tongue because of lack of fusion of lateral halves of tongue.
  • Microglossia: Tongue too small in size
  • Macroglossia: Tongue is too large in size
  • Hemiglossia: Suppression of one lingual swelling of tongue
  • Median rhomboid glossitis: It occur due to incomplete desent of tuburculum impar and entrapment of portion which lies between lateral half of the tongue. In this, there is absence of papilla in center of tongue.
Q.3. Write a short note on muscle movement and innervation of tongue.
(Apr 2007, 5 Marks)
Or
Enumerate the muscles of tongue and their nerve supply.
(March 2006, 5 Marks)
Or
Name the muscles of tongue.
(Aug 2016, 2 Marks)
Or
Write the name of extrinsic muscles of tongue.
(Oct 2016, 2 Marks)
Enumerate muscles of tongue. (Do not describe)
(Feb 2013, 2 Marks)
Ans. Tongue: Tongue is a muscular organ situated in the floor of mouth.
  • It is associated with the functions of taste, speech, mastication, and deglutition.
  • Tongue is divided into right and left halves by a middle fibrous septum.
  • Each half contains four intrinsic and four extrinsic muscles.
 
Muscles of Tongue
  • Intrinsic muscles:
    • Superior longitudinal
    • Inferior longitudinal
    • Transverse
    • Vertical.
  • Extrinsic muscles:
    • Genioglossus
    • Hyoglossus
    • Styloglossus
    • Palatoglossus.
 
113Muscle Movement of Tongue
Intrinsic muscles
Muscle movement
Superior longitudinal
Make tongue short and dorsum concave
Inferior longitudinal
Make tongue short and dorsum convex
Transverse
Make tongue narrow and elongated
Vertical
Tongue become broad and flattened
Extrinsic muscles
Muscle movement
Genioglossus
Protrude the tongue
Hyoglossus
Depress the tongue
Styloglossus
Tongue retraction
Palatoglossus
Tongue elevation
 
Innervations of Muscles of Tongue
Refer to the heading nerve supply in Ans 1 of same chapter
Q.4. Write sensory, gustatory and motor nerve supply of tongue.
(Dec 2010, 4 Marks)
Ans. For sensory and motor supply refer to Ans 1 of same chapter.
 
Gustatory Innervation
Gustatory innervation carries taste sensations.
Area
Gustatory innervation
Anterior 2/3
Chorda tympani branch of facial nerve (VII nerve)
Posterior 1/3
Glossopharyngeal nerve (IX nerve)
Posteriomost part
Vagus nerve (X nerve) of the tongue
Q.5. Answer in brief on tongue tie.
(Feb 2016, 2 Marks)
Ans. Tongue tie is also known as ankyloglossia.
  • Tongue tie is the condition which arises when the inferior frenulum attaches to the bottom of tongue and subsequently restricts free movements of the tongue.
  • It can cause feeding problems in infants.
  • It causes speech defects specially articulation of the sounds l, r, t, d, n, th, sh and z.
  • It leads to persistent gap between the mandibular incisors.
zoom view
Fig. 148: Tongue tie
Q.6. Name different types of lingual papillae.
(May 2017, 3 Marks)
Ans. Following are the lingual papillae:
  • Vallate or circumvallate papillae: They are large in size and 1 to 2 mm in diameter. They lie immediately in front of the sulcus terminalis. Each papilla is a cylindrical projection which is surrounded by the circular sulcus. Walls of papilla consist of taste buds.
  • Fungiform papillae: They are numerous near the tip as well as margins of tongue, some of them are scattered over dorsum. These papillae are smaller than vallate papillae but larger than filiform papillae. Each papilla has narrow pedicle and large rounded head.
  • Filiform papillae or conical papillae: They cover presulcal area of dorsum of tongue and provide it a velvety appearance. They are smallest and most numerous of all lingual papillae of tongue. Each of them is pointed and is covered by keratin. Apex get split into filamentous processes.
  • Foliate papillae: They are very few in number. They have in constant vertical grooves and ridges near margin in front of the sulcus terminalis. They are rudimentary in humans.
Q.7. Write a short note on pathway of taste.
(Sep 2017, 3 Marks)
Ans. Taste sensation from anterior two-third of the tongue except from vallate papillae is carried by chorda tympani branch of facial nerve upto geniculate ganglion. The central process reaches to tractus solitarius inside medulla.
zoom view
Fig. 149: Pathway of taste
  • Taste sensation from posterior one-third of the tongue include circumvallate papillae is carried by glossopharyngeal nerve upto inferior ganglion. The central process reaches to tractus solitarius.
  • 114Taste from posteriormost part of the tongue and epiglottis travels via vagus nerve upto the inferior ganglion of vagus. The central process reaches to tractus solitarius.
  • After relay in tractus solitarius, solitario thalamic tract is formed which becomes part of trigeminal leminiscus and reaches to posteroventromedial nucleus of thalamus of contralateral side. Another relay from here takes them to the lowest part of post central gyrus which is the specific area for taste.
 
18. THE EAR
Q.1. Write a short note on tympanic membrane.
(Mar 1997, 4 Marks)
Ans.
  • It is a thin, translucent partition which lies between external acoustic meatus and middle ear.
  • It is oval in shape and is placed obliquely at an angle of 55° with floor of meatus.
  • Membrane has outer and inner surface.
  • Outer surface of membrane is lined by thin skin and is concave.
  • Inner surface provides attachment to handle of malleus which extends upto its center. Inner surface is convex.
zoom view
Fig. 150: A. External surface of tympanic membrane; B. Inner surface of tympanic membrane
  • Point of maximum convexity lies at tip of the handle of the malleus and is known as umbo.
  • Membrane is thick at the circumference and is fixed to tympanic sulcus of temporal bone on tympanic plate. Superiorly sulcus is deficient.
  • At sulcus membrane is attached to tympanic notch.
  • At ends of the notch two bands, i.e. anterior and posterior malleolar folds get prolonged to lateral process of malleus.
  • Greater part of tympanic membrane is tightly attached and is known as pars tensa.
  • Part between two malleoler folds is loose and is known as pars flaccid.
  • Chorda tympani crosses pars flaccid and this part is more liable to rupture as compared to pars tensa.
  • Tympanic membrane is held tense by the inward pull of tensor tympani muscle which get inserted in upper end of handle of malleus.
 
Structure
Tympanic membrane consists of following three layers:
  1. The outer auricular layer of skin.
  2. The middle fibrous layer made up of superficial radiating fibers and deep circular fibers.
  3. The inner mucous layer is lined by a low ciliated columnar epithelium.
 
Blood Supply
  • Outer surface supplied by the deep auricular branch of maxillary artery.
  • Inner surface is supplied by anterior tympanic branch of maxillary artery and by posterior tympanic branch of stylomastoid branch of posterior auricular artery.
 
Venous Drainage
Veins from outer surface drains to external jugular vein. Those from inner surface drains into transverse sinus and into venous plexus around auditory tube.
zoom view
Fig. 151: Inner surface of tympanic membrane
 
115Lymphatic Drainage
Lymphatics pass to preauricular and retropharyngeal lymph nodes.
 
Nerve Supply
  • Outer surface: Anteroinferior part is supplied by auriculotemporal nerve and posterosuperior part by auricular branch of vagus nerve along with communicating branch from facial nerve.
  • Inner surface: It is supplied by tympanic branch of glossopharyngeal nerve via tympanic plexus.
Q.2. Write a short note on auditory ossicles.
(Feb 2002, 3 Marks)
Ans. Auditory ossicles are also known as ear ossicles.
There are three auditory ossicles, i.e. malleus, incus and stapes.
 
Malleus
  • It is so called because it resembles as a hammer.
  • Malleus is the largest and most laterally placed ossicle.
  • It consists of following parts:
    • Round head: It lies in epitympanic recess. Head articulates posteriorly with body of incus. Head provide attachment to superior and lateral ligaments.
    • Neck: It lies against pars flaccida and is related medially to chorda tympani nerve.
    • Anterior process: It is connected to the petrotympanic fissure by the anterior ligament.
    • Lateral process: It projects from upper end of handle and gives attachment to malleolar folds.
    • Handle: It extends downwards, backward and medially, it is attached to upper half of tympanic membrane.
 
Incus or Anvil
  • It is known as anvil because it resembles as an anvil which is used by Blacksmiths.
  • Incus resembles a molar tooth and consists of following parts:
    • Body: It is large and has an articular surface which is directed forwards. It articulates along with the head of malleus.
    • Long process: It projects downwards just behind and parallel along with handle of malleus. Its tip bears a lentiform nodule which is directed medially and articulates with head of stapes.
 
Stapes
  • Stapes is so called because its shaped is like a stirrup.
  • This is the smallest, and the most medially placed ossicle.
  • It consists of following parts:
    • Small head: It consists of a concave facet which articulates with lentiform nodule of the incus.
    • Narrow neck: This provides insertion, posteriorly, to the thin tendon of the stapedius.
    • Two limbs or crura: Anterior one is shorter and less curved while posterior one is longer which diverge from neck and are attached to the footplate.
    • Footplate, a footpiece or base: It is oval in shape and fits into the fenestra vestibuli.
 
Joints of Ossicles
  • Incudomalleolar joint is a saddle joint.
  • Incudostapedial joint is a ball and socket joint. Both of them are synovial joints. They are surrounded by capsular ligaments. There are three accessory ligaments for malleus, and one each for incus and stapes which stabilize the ossicles. All ligaments are extremely elastic.
zoom view
Fig. 152: Ossicles of ear
Q.3. Write a short note on boundaries of middle ear.
(Apr 2010, 5 Marks)
Ans. Boundaries of middle ear are as follows:
 
Roof or Tegmental Wall
  • It separates middle ear from middle cranial fossa.
  • This wall is formed by thin plate of bone known as tegmen tympani. This plate is prolonged backwards as roof of canal for tensor tympani.
 
Floor of Jugular Wall
  • It is formed by thin plate of bone which separates middle ear from superior bulb of internal jugular vein. This plate is the part of temporal bone.
  • Near medial wall, floor presents tympanic canaliculus which transmit tympanic branch of glossopharyngeal nerve to medial wall of middle ear.
 
Anterior or Carotid Wall
  • It is narrow because of approximation of medial and lateral walls and due to descendent of roof.
  • Uppermost part of anterior wall consists of opening of canal for tensor tympani.
  • Middle part consists of opening of auditory tube.116
zoom view
Fig. 153: Boundaries of middle ear
  • Inferior part of wall is formed by thin plate of bone which forms posterior wall of carotid canal. This thin plate of bone separates middle ear from internal carotid artery. The plate is perforated by superior and inferior sympathetic caroticotympanic nerves and tympanic branch of internal carotid artery.
  • Bony septum between canals for tensor tympani and auditory tube continued posteriorly on medial wall as curved lamina known as processes cochleariformis.
 
Posterior or Mastoid Wall
It presents these features from above to downward:
  • Superiorly there is presence of an opening or aditus via which epitympanic recess communicates with mastoid or tympanic antrum.
  • Fossa incudis is a depression which lodges short process of incus.
  • Conical projection known as pyramid lie near junction of posterior and medial wall. It consists of an opening at its apex for passage of tendon of stapedius muscle.
  • Lateral to the pyramid and near the posterior edge of tympanic membrane lies posterior canaliculus for chorda tympani nerve via which nerve enters middle ear cavity.
 
Lateral or Membranous Wall
  • It separates middle ear from external acoustic meatus and is formed mainly by tympanic membrane along with tympanic ring and sulcus and partly by squamous temporal bone.
  • Near the tympanic notch, there are two small apertures, i.e. petrotympanic fissure which lie in front of upper end of bony rim and anterior canaliculus for chorda tympani nerve which lie either in fissure or in front of it. Chorda tympani nerve leaves middle ear via this canaliculus to emerge at base of skull.
 
Medial Wall
It separates middle ear from the internal ear. It shows following features:
  • Promontory: This is a rounded bulging which is produced by first turn of cochlea. This is grooved by tympanic plexus.
  • Fenestra vestibuli: It is an oval opening posterosuperior to promontory. It leads inside vestibule of an internal ear and is closed by footplate of stapes.
  • Prominence of facial canal: It run backward just above the fenestra vestibule and reach lower margin of aditus. Canal now descend behind posterior wall to end at stylomastoid foramen.
  • Fenestra cochleae: It is round opening at bottom of depression posteroinferior to promontory. It open inside scala tympani of cochlea and is closed by secondary tympanic membrane.
  • Sinus tympani: It is a depression behind promontory, opposite to ampulla of posterior semicircular canal.
  • Processus cochleariformis.
  • Prominance of lateral semicircular canal above facial canal.
Q.4. Draw a labeled diagram of lateral wall of middle ear.
(Mar 1998, 4 Marks)
Ans.
zoom view
Fig. 154: Lateral wall of middle ear
117Q.5. Name the contents of middle ear cavity.
(Aug 2016, 2 Marks)
Ans. Following are the contents of middle ear cavity:
  • Three small bones or ossicles, i.e. malleus, incus and stapes. Upper half of malleus and greater part of incus remain in epitympanic recess.
  • Ligaments of ear ossicles
  • Two muscles, i.e. tensor tympani and stapedius
  • Vessels supplying and draining middle ear
  • Nerves i.e. chorda tympani and tympanic plexus
  • Air.
 
19. MISCELLANEOUS
Q.1. Give explanation of dryness of mouth.
(Feb 2013, 5 Marks)
Ans. It is also known as xerostomia.
It is the dryness of mouth, which is a clinical manifestation of salivary gland dysfunction.
 
Etiology
  1. Radiation induced: Ionizing radiation to head and neck region for treatment of cancer results in pronounced changes in salivary glands located within primary beam.
  2. Pharmacologically induced xerostomia: Drugs causes decreased salivary flow are anticonvulsants, antiemetics, antihistamines, antihypertensives and antispasmodics.
  3. Systemic alterations resulting in xerostomia: Certain deficiency states like pernicious anemia, iron deficiency anemia and deficiency of vitamin A and hormone can cause xerostomia.
  4. Fluid loss associated with hemorrhage, sweating, diarrhea, vomiting and diabetes insipidus.
  5. Developmental abnormalities of salivary gland.
  6. Systemic disease.
 
Clinical Features
  1. Effect of xerostomia on oral functions:
    • Increased thirst, increased uptake of fluid while eating.
    • Frequent use of chewing gums and consumption of sour candy.
    • Burning and tingling sensations in mouth.
    • Painful salivary gland enlargement.
    • Oral infections, intolerance to dental appliances.
  2. Effect of xerostomia on normal functions:
    • Blurred vision and ocular dryness, itching, burning in the eyes.
    • Dryness of pharynx and skin. Itching and burning sensation of vagina.
  3. Clinical signs of xerostomia:
    • Dryness of lining of oral mucosa.
    • Tongue blade may adhere to soft tissues.
    • Increase incidence of dental caries.
    • Candidiasis—pseudomembranous.
    • Angular chelitis.
 
Management
  1. Stimulation of salivary production:
    1. Local stimulation: By chewing gums, mints, paraffin and citric acid containing lozenges and rinses.
    2. Systemic stimulation.
    3. Bromhexine 1/m/4–8 mg TDS.
    4. Amethole trithionate 1/m/25 mg TDS.
    5. Pilocarpine 1/m/5 mg TDS.
  2. Symptomatic treatment: Salivary substitutes are given.
  3. Suggestion to patient having xerostomia.
    1. Try very sweet or tart foods and beverages such as lemonade.
    2. Try sucking ice cubes.
    3. Use soft and liquid foods.
    4. Avoid dry foods, chocolate, pastry.
    5. Avoid over salty foods.
    6. Have a sip of water in every few minutes which helps in swallowing.
Q.2. Give explanation of lockjaw.
(Feb 2013, 5 Marks)
Ans. Lockjaw is also known as tetanus
It is a disease of nervous system characterized by intensive activity of motor neuron and resulting in severe muscles spasm.
 
Mechanism of Lockjaw
  • Clostridium tetani enters through large or small or even unrecognized wound. Deep, infected punctures are most susceptible as organism thrives best anaerobically.
  • Exotoxins such as tetanospasmin and tetanolysin are produced by bacteria.
  • Tetnospasmin released by the bacteria travels along perineural sheath, lymphatics along the nerve and via blood to cause its effects.
  • Tetanospasmin cleave into light part, i.e. fragment A and heavy part, i.e. fragment B.
  • Fragment B binds to nerve receptors and fragment A blocks the neurotransmitter.
  • Fragment A blocks release of inhibitory neurotransmitters, i.e. glycine and GABA. Loss of inhibition alters the firing rate of alpha motor neuron leading to lockjaw due to rigidity and spasm of muscles, sympathetic overactivity.
  • Tetanospasmin rapidly bind to gangliosides at presynaptic membrane of inhibitory motor nerve endings.
Q.3. Give explanation about radiating pain of teeth.
(Feb 2013, 5 Marks)
Ans. Radiating pain is also known as referred pain. The pain sensation produced in some parts of body is felt in other structures away from place of development. This is called referred pain or radiating pain.
 
Mechanism of Radiating Pain
Dermatomal rule: Pain is referred to a structure, which is developed from same dermatome from which pain producing structure is developed. This is dermatomal rule.
A dermatome includes all the parts and structure of body.
118For example, heart and inner aspect of left arm originate from some dermatome so, pain in heart is referred to left arm.
Examples of referred pain:
  1. Pain in ovary is referred to umbilicus
  2. Pain in testis is referred to abdomen
  3. Pain in diaphragm is referred to right shoulder
  4. Renal pain is referred to loin
  5. Tooth pain felt in ear.
Q.4. Write short note on classification of glands.
(Mar 2013, 3 Marks)
Ans. Following is the classification of glands:
  1. According to mode of secretion
    • Exocrine glands: Secretions are carried via ducts to target cells
    • Endocrine glands: Secretions are secreted directly in circulatory system
    • Paracrine glands: Their secretions diffuse locally to cellular targets in an immediate surrounding.
  2. According to mechanism of secretion
    • Merocrine glands: Secretions are packed into vesicles. Vesicle membrane fuses with plasma membrane to release their contents to exterior, e.g. simple sweat glands
    • Apocrine glands: In these glands some of apical cytoplasm is lost along with secretion, e.g. mammary glands
    • Holocrine glands: Cells are filled with secretory products and entire cell disintegrate to release its secretion, e.g. sebaceous glands.
  3. Structural and functional classification
    • Unicellular glands: They are made of single cells which are interspersed between nonsecretory epithelial lining, e.g. goblet cell
    • Multicellular glands: It consists of many cells in sheets or clusters with common secretory function, e.g. mucous lining of stomach
    • Simple tubular glands without ducts: Cells are arranged in a tubular fashion and open on epithelial surface without a duct.
    • Simple tubular glands with duct: Secreting cells are arranged in tubular shaped structures with upper nonsecretory parts which act as ducts.
    • Simple branched tubular glands: Consists of single duct with branched tubular arrangement of secretory cells.
    • Simple coiled tubular glands: Secretory part is coiled and they have single duct
    • Simple acinar or alveolar glands: Secretory part is flask shape with connecting duct.
    • Compound glands: In these glands ducts are branched. These glands may be branched tubuloalveolar or branched tubular or branched alveolar type according to shape of secretory part.
  4. According to secretion
    • Mucous secreting or mucus glands: They secrete mucous, e.g. sublingual salivary gland.
    • Serous glands: They secrete serum, e.g. parotid gland.
119FUNCTIONAL ANATOMY OF MUSCULOSKELETAL SYSTEM
 
1. SKELETON
Q.1. Write short note on blood supply of bone.
(Aug 2005, 4 Marks)
Ans.
 
Arterial Supply
In Long Bone
Blood supply of a long bone is derived from the following sources:
Nutrient Artery
  • This artery enters the shaft via nutrient foramen, runs obliquely through cortex, and divides into ascending and descending branches inside medullary cavity.
  • Each of the branches divides into number of small parallel channels which get terminate inside adult metaphysis by anastomosing with epiphysial, metaphysial and periosteal arteries.
  • Nutrient artery supplies medullary cavity, inner two-third of cortex and metaphysis.
  • Nutrient foramen is directed away from growing end of bone.
Periosteal Arteries
  • They are numerous beneath muscular and ligamentous attachments.
  • These arteries ramify beneath the periosteum and enter inside Volkmann's canals to supply the outer 1/3 of cortex.
Epiphysial Arteries
  • These arteries are derived from periarticular vascular arcades also known as circulus vasculosus which is found over nonarticular bony surface.
  • Out of these multiple vascular foramina in this region, only a few admit the arteries (epiphysial and metaphysial), and rest are venous exits.
  • Number as well as size of these foramina can give an idea of relative vascularity of the two ends of a long bone.
Metaphysial Arteries
  • They are derived from neighboring systemic vessels.
  • These arteries pass directly into the metaphysis and reinforce metaphysial branches from the primary nutrient artery.
  • Inside miniature long bones, infection begins in middle of shaft rather than at the metaphysis because nutrient artery breaks up into a plexus immediately on reaching medullary cavity. In adults, the chances of infection are decreased because nutrient artery is mostly replaced by the periosteal vessels.
In Long Short Bones
  • Nutrient artery enters inside middle of shaft and divides to form plexus.
  • Periosteal artery supplies to major part of bone and can replace the nutrient artery.
In Short Bones
They are supplied by the numerous periosteal vessels which enter inside their nonarticular surfaces.
In Vertebra
  • In vertebra, body is supplied by anterior and posterior vessels.
  • Vertebral arch is supplied by the large vessels entering the bases of transverse processes.
  • Bone marrow is drained by two large basivertebral veins.
  • Foramina lie over posterior aspect of body of vertebrae.
Rib
It is supplied by the nutrient artery which enters just beyond the tubercle and periosteal arteries.
 
Venous Drainage
There are numerous veins and they are larger in the cancellous, red marrow containing bones (e.g. basivertebral veins). In the compact bone, they accompany arteries in the Volkmann's canals.
zoom view
Fig. 155: Blood supply of long bone
120Q.2. Describe in brief epiphysis.
(Nov 2009, 5 Marks)
Ans. Epiphysis is the rounded end of a long bone, at its joint with adjacent bone.
  • At the joint, epiphysis is covered with articular cartilage; below that covering is a zone similar to the epiphyseal plate, known as subchondral.
  • It is the part of bone which ossifies from secondary center
  • Epiphysis is filled with red bone marrow, which produces erythrocytes (red blood cells).
zoom view
Fig. 156: Epiphysis
 
Types
There are four types of epiphysis:
  1. Pressure epiphysis: Region of the long bone that forms the joint is called pressure epiphysis. For example the head of femur which is a part of the hip joint complex is a pressure epiphyses. These epiphyses assists in transmitting the weight of the human body and are the regions of the bone which is under pressure during movement, or locomotion hence they are named pressure epiphyses.
  2. Traction epiphyses: Regions of the long bone which are nonarticular, i.e. not involved in the joint formation is called as traction epiphysis. It is mainly formed due to pull of muscles. Traction epiphyses ossify later than the pressure epiphyses. Examples of these epiphyses are tubercles of humerus (greater tubercle and lesser tubercle), trochanters of the femur (both greater and lesser), etc.
  3. Atavistic epiphyses: As Homo Sapiens evolved from being four legged to two legged, their lower limbs became stronger and hands became free from being actively involved in locomotion. This fused certain bones together due to the change in functionality over generations. These type of fused bones are called as Atavistic. These independent bones which get attached to host bone secondarily to receive nutrition. Example of this is the coracoid process of scapula which has been fused in humans but separate in four legged animals.
  4. Aberrant epiphysis: These epiphysis are deviations from the normal and are not always present. For example, the epiphyses at the head of the first metacarpal bone.
Q.3. Classify bones.
(Feb 2013, 5 Marks)
Ans. Following is the classification of bones:
 
According to Shape
  • Long bones: Each of the long bone consists of an elongated shaft (diaphysis) and two expanded ends (epiphyses) which are smooth and articular. Shaft typically consists of three surfaces separated by 3 borders, a central medullary cavity, and a nutrient foramen directed away from the growing end. Examples:
    • Typical long bones like humerus, radius, ulna, femur, tibia and fibula
    • Miniature long bones have only one epiphysis like metacarpals, metatarsals, and phalanges
    • Modified long bones have no medullary cavity like clavicle.
  • Short bones: Their shape is usually cuboid or scaphoid. Examples are tarsal and carpal bones.
  • Flat bones: They resemble as shallow plates and form boundaries of certain body cavities. Examples are bones in the vault of the skull, ribs, sternum and scapula.
  • Irregular bones: Examples are vertebra, hip bone, and bones in the base of skull.
  • Pneumatic bones: Certain irregular bones which consists of large air spaces which are lined by epithelium. Examples are maxilla, sphenoid, ethmoid, etc.
  • Sesamoid bones: These are bony nodules which are found embedded inside the tendons or joint capsules. They have no periosteum and ossify after birth. Examples are patella, pisiform, fabella, etc.
  • Accessory (supernumerary) bones: They are not always present. These may occur as ununited epiphyses developed from extra centers of ossification. Examples: sutural bones, lateral tubercle of talus, tuberosity of 5th metatarsal, etc.
  • Heterotopic bones: Bones sometimes develop in soft tissues, e.g. horse riders develop bones in adductor muscles (rider's bones).
 
Developmental Classification
  • Membrane (dermal) bones: These bones ossify inside the membrane (intramembranous or mesenchymal ossification), and are derived from mesenchymal condensations. Examples are bones of the vault of skull as well as facial bones.
    • Cartilaginous bones ossify inside cartilage (intracartilaginous or endochondral ossification), and are derived from preformed cartilaginous models. Examples are bones of limbs, vertebral column and thoracic cage.
    • 121Membrano-cartilaginous bones ossify partly inside membrane and partly inside the cartilage. Examples: clavicle, mandible, occipital, temporal, sphenoid.
  • Somatic bones: Most of the bones are somatic.
  • Visceral bones: These bones develop from pharyngeal arches. Examples are hyoid bones, part of mandible and ear ossicles.
 
Regional Classification
  • Axial skeleton: It consists of skull, vertebral column, and thoracic cage.
  • Appendicular skeleton: It consists of bones of limbs.
 
Structural Classification
  • Macroscopically, the architecture of bone may be compact or cancellous:
    • Compact bone: It is dense in texture, but is extremely porous. It is best developed in the cortex of the long bones. This is an adaptation to bending and twisting forces.
    • Cancellous or spongy, or trabecular bone: It is open in texture and is made up of a meshwork of trabeculae between which are marrow containing spaces. Trabecular meshworks are of three primary types, i.e.:
      1. Meshwork of rods
      2. Meshwork of rods and plates
      3. Meshwork of plates.
      Cancellous bone is an adaptation to the compressive forces.
  • Microscopically: Bone is of five types, namely lamellar, woven, fibrous, dentine and cementum.
    1. Lamellar bone: Most of the mature human bones, either compact or cancellous consist of thin plates of bony tissue known as lamellae. These are arranged in piles inside a cancellous bone, but in concentric cylinders, i.e. Haversian system or secondary osteon inside a compact bone.
    2. Woven bone: This is seen in fetal bone, fracture repair and in cancer of bone
    3. Fibrous bone: This is found in young fetal bones, but is common in reptiles and amphibia.
    4. Dentine
    5. Cementum occurs inside the teeth.
Q.4. Write short note on osteogenesis.
(June 2010, 5 Marks)
Ans. Bones are first laid down as mesodermal (connective tissue) condensations. Conversion of mesodermal models into bone is called intramembranous or mesenchymal ossification, and the bones are called membrane (dermal) bones.
However, mesodermal stage may pass through cartilaginous stage by chondrification during 2nd month of intrauterine life. Conversion of cartilaginous model into bone is called intracartilaginous or endochondral ossification, and such bones are called cartilaginous bones.
Ossification takes place by centers of ossification, each one of which is a point where laying down of lamellae (bone formation) starts by the osteoblasts situated on the newly formed capillary loops. The centers of ossification may be primary or secondary. The primary centers appear before birth usually during 8th week of intrauterine life; the secondary centers appear after birth, with a few exceptions of lower end of femur and upper end of tibia. Many secondary centers appear during puberty.
A primary center forms diaphysis, and the secondary centers form epiphyses. Fusion of epiphyses with the diaphysis starts at puberty and is complete by the age of 25 years, after which no more bone growth can take place. The law of ossification states that secondary centers of ossification which appear first are last to unite. The end of a long bone where epiphysial fusion is delayed is called the growing end of the bone.
 
Growth of a Long Bone
  • Bone grows in length by multiplication of cells in the epiphysial plate of cartilage.
  • Bone grows in thickness by multiplication of cells in the deeper layer of periosteum.
  • Bones grow by deposition of new bone on the surface and at the ends. This process of bone deposition by osteoblasts is called appositional growth or surface accretion. However, in order to maintain the shape the unwanted bone must be removed. This process of bone removal by osteoblasts is called remodelling. This is how marrow cavity increases in size.
 
2. JOINTS
Q.1. Write in brief on fibrous joints.
(Aug/Sep 1998, 4 Marks) (Dec 2010, 5 Marks)
Ans. In fibrous joints bones are joined by fibrous tissue. Fibrous joints are either immovable or permit slight degree of movement.
Fibrous joint are grouped into three types:
  1. Sutures
  2. Syndesmosis
  3. Gomphosis
 
Sutures
  • They are present only inside the skull.
  • Two of the bones get separated by the connective tissue.
  • Sutural side of each of the bone is covered by layer of osteogenic cells or cambial layer, covered by the capsular layer which is continuous with periosteum.
  • Area between the bones reduces with the age, so osteogenic surfaces get opposed.
  • Sutures become synostose and become obliterated as the age advances.
  • Sutures are peculiar to skull, and are immovable.
  • According to the shape of bony margins, the sutures can be:
    • Plane, e.g. internasal suture
    • Serrate, e.g. interparietal suture
    • 122Squamous, e.g. temporoparietal suture
    • Denticulate, e.g. lambdoid suture
    • Schindylesis type, e.g. between rostrum of sphenoid and upper border of vomer.
  • Neonatal skull consists of fontanelles and these are temporary in nature. At six specific points over sutures inside the newborn skull are present membrane filled gaps known as “fontanelles”. These membrane filled gaps allow underlying brain to increase in size. All these fontanelles become bone by 18 months.
zoom view
Fig. 157: Sutural joint
 
Syndesmosis
This is the fibrous union in between the bones. This can be represented as interosseous ligament as seen in inferior tibiofibular joint or as a tense membrane in posterior part of sacroiliac joint.
zoom view
Fig. 158: Syndesmosis
 
Gomphosis
  • Gomphosis is a type of fibrous joint.
  • It is a peg and socket junction between tooth and its socket.
  • Periodontal ligament connects dental element to alveolar nerve.
  • Gomphosis is an articulation between two bones.
zoom view
Fig. 159: Gomphosis
Q.2. Write a short note on characteristics of synovial joint.
(Sep 2004, 5 Marks)
Ans.
  • Articular surfaces are covered by hyaline (articular) cartilage which is a fibrocartilage in certain membrane bones. Articular cartilage is avascular, nonnervous and is elastic. It is lubricated with synovial fluid, cartilage provides slippery surfaces for free movements such as 'ice on ice'. Surface of articular cartilage shows fine undulations which are filled with the synovial fluid.
  • Between articular surfaces there is presence of a joint cavity which is filled with synovial fluid. The cavity can be partially or completely subdivided by an articular disc or meniscus.
  • Synovial joint is surrounded by an articular capsule which is formed of a fibrous capsule which is lined by synovial membrane. Due to its rich nerve supply, fibrous capsule is sensitive to stretches imposed by movements. This sets up most appropriate reflexes to protect the joint from any type of sprain. This is known as 'watch-dog' action of capsule.
    Fibrous capsule is often reinforced by:
    • Capsular or true ligaments which represent thickenings of fibrous capsule.
    • The accessory ligaments which can be intra or extracapsular.
  • Synovial membrane completely lines the interior of the joint except for the articular surfaces covered by hyaline cartilage. The membrane produces a slimy viscous fluid known as synovial or synovial fluid which provides lubrication to joint and nourishes articular cartilage. Viscosity of fluid is because of hyaluronic acid which is secreted by cells of synovial membrane.
  • Varying degrees of movements are permitted by the synovial joints.123
zoom view
Fig. 160: Synovial joint
Q.3. Write a short note on gomphosis and arteries supplying various teeth.
(Feb 2005, 15 Marks)
Ans. The answer of gomphosis is given in same chapter in Ans 1 and the answer of arteries supplying various teeth is given in chapter THE MOUTH AND PHARYNX in Ans 11.
Q.4. Write a short note on synovial joints.
(Sep 2006, 3 Marks)
Ans. Synovial joints are also known as diarthrosis.
  • Synovial joints are the freely movable joints, but in some of them movement is restricted due to the shape of their articulating surfaces and by ligaments which hold the bones together. Such ligaments are of elastic connective tissue.
  • A synovial joint consists of fluid-filled cavity between its articular surfaces which get covered by articular cartilage. Fluid present is known as synovial fluid. Synovial fluid is produced by synovial membrane which lines the cavity except for the actual articular surfaces and covers any ligaments or tendons which pass through the joint.
  • Synovial fluid basically acts as a lubricant.
  • The form of articulating surfaces controls the type of movement which occurs at any joint.
 
Classification of Synovial Joints According to Functional Classification of Joints
Type of joint
Movement
Plane or gliding type
Gliding movement
Uniaxial joints
  • Hinge joint
  • Pivot joint
  • Flexion and extension
  • Rotation
Biaxial joints
  • Condylar joint
  • Ellipsoid joint
  • Flexion, extension and limited rotation
  • Flexion, extension, abduction, adduction and circumduction
Multiaxial joints
  • Saddle joint
  • Ball-and-socket joint
  • Flexion and extension, abduction, adduction and conjunct rotation
  • Flexion and extension, abduction and adduction, circumduction, medial and lateral rotation
 
Synovial Joints According to Structural Classification of Joints
  • Plane synovial joints: In these joints articular surfaces are more or less flat. These joint permit gliding movements in various directions. E.g. intercarpal joints, intertarsal joints, joints between articular processes of vertebrae, cricothyroid joint, cricoarytenoid joint etc.
  • Hinge joints: In these type of synovial joints articular surfaces are of pulley-shaped. There are strong collateral ligaments. Movements are permitted in one plane only at around a transverse axis. Examples are elbow joint, Ankle joint and interphalangeal joints.
  • Pivot (trochoid) joints: In these type of synovial joints articular surfaces consists of a central bony pivot (peg) which is surrounded by an osteoligamentous ring. Movements are permitted only in one plane at around a vertical axis. Examples are superior and inferior radio-ulnar joints and median atlanto-axial joint.
  • Condylar (bicondylar) joints: In these synovial joints articular surfaces consists of two distinct condyles (convex male surfaces) which fit inside reciprocally concave female surfaces (which are also known as condyles). These joints permit movements mainly in one plane at around a transverse axis, but partly in another plane (rotation) around a vertical axis. Examples are knee joint and right and left temporomandibular joint.
  • Ellipsoid joints: In these type of synovial joints articular surfaces include an oval, convex, male surface which fit into an elliptical, concave female surface. Free movements should be permitted around both axes, flexion and extension around the transverse axis and abduction as well as adduction around the anteroposterior axis. Combination of movements produces circumduction. Typical rotation around a third (vertical) axis does not occur. Examples are wrist joint, metacarpophalangeal joints and atlanto-occipital joints.
  • Saddle (sellar) joints: In these synovial joints articular surfaces are reciprocally concavo-convex. Movements are similar to those which are permitted by an ellipsoid joint, with addition of some of rotation (conjunct rotation) around a third axis which cannot occur independently. Examples are first carpometacarpal joint, sternoclavicular joint, calcaneocuboid joint, etc.
  • Ball-and-socket (spheroidal) joints: In these ball and socket joints articular surfaces include a globular head (male surface) which fit inside a cup-shaped socket (female surface). Movements in these joint occur around an indefinite number of axes which consists of one common center. Flexion, extension, abduction, adduction, medial rotation, lateral rotation, and circumduction, all the movements occur freely. Examples are shoulder joint, hip joint, etc.
Q.5. Enumerate the types of joints with example.
(Apr 2007, 5 Marks)
Ans. Joint is a junction between two or more bones and is responsible for movement, growth or transmission of forces.
 
124Structural Classification
  • Fibrous joints
    • Sutures, e.g. internasal suture and interparietal suture
    • Syndesmosis, e.g. in posterior part of sacroiliac joint
    • Gomphosis, e.g. joint between tooth and its socket.
  • Cartilaginous joints
    • Primary cartilaginous joints or synchondrosis, e.g. spheno-occipital joint
    • Secondary cartilaginous joints or symphysis, e.g. manubriosternal joints.
  • Synovial joints
    • Ball-and-socket or spheroidal joints, e.g. shoulder joint and hip joint
    • Sellar or saddle joints, e.g. sternoclavicular joint
    • Condylar or bicondylar joints, e.g. knee joint
    • Ellipsoid joints, e.g. wrist joint
    • Hinge joints, e.g. elbow joint and ankle joint
    • Pivot or trochoid joints, e.g. median atlantoaxial joint
    • Plane joints, e.g. intercarpal joint, intertarsal joint.
 
Functional Classification (According to the Degree of Mobility)
  • Synarthrosis (immovable), like fibrous joints.
  • Amphiarthrosis (slightly movable), like cartilaginous joints.
  • Diarthrosis (freely movable), like synovial joints.
 
Regional Classification
  • Skull type: Immovable.
  • Vertebral type: Slightly movable.
  • Limb type: Freely movable.
 
According to Number of Articulating Bones
  • Simple joint: When two bones articulate, e.g. interphalangeal joints.
  • Compound joint: More than two bones articulate within one capsule, e.g. elbow joint, wrist joint.
  • Complex joint: When joint cavity is divided by an intra-articular disc, e.g. temporomandibular joint and sternoclavicular joint.
Q.6. Enumerate the types of synovial joint and write in brief about ball-and-socket joint.
(Dec 2012, 4 Marks)
Ans.
 
Enumeration of Types of Synovial Joint
According to functional classification of joints synovial joints are:
  • Plane or gliding type
  • Uniaxial joints
    • Hinge joint
    • Pivot joint
  • Biaxial joints
    • Condylar joint
    • Ellipsoid joint
  • Multiaxial joints
    • Saddle joint
    • Ball-and-socket joint
According to structural classification of joints synovial joints are:
  • Plane synovial joints
  • Hinge joints
  • Pivot (trochoid) joints
  • Condylar (bicondylar) joints
  • Ellipsoid joints
  • Saddle (sellar) joints
  • Ball-and-socket (spheroidal) joints.
 
Ball-and-Socket Joint
  • It is a multiaxial type of synovial joint.
  • It is also known as spheroidal joint.
  • In ball-and-socket joint the articular surfaces include a globular head (male surface) which fit inside a cup-shaped socket (female surface).
  • Movements in these joint occur around an indefinite number of axes which consists of one common center.
  • Flexion, extension, abduction, adduction, medial rotation, lateral rotation, and circumduction, all the movements occur freely.
  • Examples are shoulder joint, hip joint, talocalcaneonavicular joint and incudostapedial joint.
Q.7. Write about classification of joints.
(Dec 2009, 5 Marks)
Or
Write briefly on classification of joints.
(Aug 2012, 5 Marks)
Ans. Following is the classification of joints:
 
Structural Classification
  • Fibrous joints: Joined by dense irregular connective tissue which are rich in collagen fibers:
    • Sutures, e.g. internasal suture and interparietal suture
    • Syndesmosis, e.g. in posterior part of sacroiliac joint
    • Gomphosis, e.g. joint between tooth and its socket.
  • Cartilaginous joints: They are joined by cartilage:
    • Primary cartilaginous joints or synchondrosis, e.g. spheno–occipital joint
    • Secondary cartilaginous joints or symphysis, e.g. manubriosternal joints
  • Synovial joints: Bones have a synovial cavity and are united by the dense irregular connective tissue that forms the articular capsule that is normally associated with accessory ligaments.
    • Ball-and-socket or spheroidal joints
    • Sellar or saddle joints, e.g. sternoclavicular joint
    • Condylar or bicondylar joints, e.g. knee joint
    • Ellipsoid joints, e.g. wrist joint
    • Hinge joints, e.g. elbow joint and ankle joint
    • Pivot or trochoid joints, e.g. median atlantoaxial joint
    • Plane joints, e.g. intercarpal joint, intertarsal joint
 
Functional Classification (According to the Degree of Mobility)
  • Synarthrosis: Permits little or no mobility. Most synarthrosis joints are fibrous joints, e.g. skull sutures.
  • 125Amphiarthrosis: Permits slight mobility. Most amphiarthrosis joints are cartilaginous joints, e.g. intervertebral discs.
  • Diarthrosis: Freely movable. All diarthrosis joints are synovial joints, e.g. shoulder, hip, elbow, knee, etc.
 
Regional Classification
  • Skull type: Immovable.
  • Vertebral type: Slightly movable.
  • Limb type: Freely movable.
 
According to Number of Articulating Bones
  • Simple joint: When two bones articulate, e.g. interphalangeal joints
  • Compound joint: More than two bones articulate within one capsule, e.g. elbow joint, wrist joint.
  • Complex joint: When joint cavity is divided by an intra-articular disc, e.g. temporomandibular joint and sternoclavicular joint.
 
3. CIRCULATORY SYSTEM
Q.1. Write short note on anastomosis.
(Mar 2006, 3 Marks)
Ans. Precapillary or postcapillary communication between neighboring vessels is known as anastomoses. Circulation via anastomosis is known as collateral circulation.
 
Types
  • Arterial anastomoses: This is the communication between the arteries or branches of arteries. It can be actual or potential.
    • In an actual arterial anastomosis arteries meet end to end, e.g. palmar arches, plantar arch, circle of Willis, intestinal arcades, labial branches of facial arteries.
    • In potential arterial anastomoses communication takes place between terminal arterioles. Such communications may dilate only gradually for collateral circulation. So on sudden occlusion of main artery, anastomoses may fail to compensate the loss, e.g. it is seen in coronary arteries as well as cortical branches of cerebral arteries.
  • Venous anastomoses: This is the communication between veins or the tributaries of veins, e.g. dorsal venous arches of hand and foot.
  • Arteriovenous anastomosis (shunt): This is a communication between an artery and a vein. It serves as function of phasic activity of an organ.
    • When an organ is active such shunts get closed and blood circulates via the capillaries. But, when the organ is at rest, blood bypasses capillary bed and is shunted back via arteriovenous anastomosis.
    • Shunt vessel can be straight or coiled and possesses a thick muscular coat, and is under the influence of sympathetic system.
    • Shunts of simple structure are found inside skin of nose, lips and external ear; in the mucous membrane of nose and alimentary canal; the coccygeal body; the erectile tissue of sexual organs; the tongue; the thyroid gland and sympathetic ganglia.
    • Specialized arteriovenous anastomoses are seen inside the skin of digital pads as well as nail beds. They form a number of small units known as glomera.
    • Preferential thoroughfare channels are also a kind of shunts. They course via capillary network. Many true capillaries arise as their side branches. One thoroughfare channel with its associated capillaries forms a microcirculatory unit. The size of the unit is variable from 1–2 to 20–30 true capillaries. The number of active units varies from time to time.
Q.2. Write short note on collateral circulation.
(June 2010, 5 Marks)
Ans. Collateral circulation is the process in which a system of small, normally closed arteries connect and start to carry blood to part of the heart when a coronary artery is blocked, or to part of the brain when a cerebral artery is blocked. These arteries can serve as alternate routes of blood supply.
 
Cerebral Collateral Circulation
Blood flow to the brain is maintained via a network of collateral arteries that anastomose in the circle of Willis, which lies at the base of the brain. In circle of Willis so-called communicating arteries exist between the front (anterior) and back (posterior) parts of the circle of Willis, as well as between the left and right side of the circle of Willis.
 
Cardiac Collateral Circulation
Another example is where a person suffers an acute myocardial infarction (heart attack). Collateral circulation in the heart tissue will sometimes bypass the blockage in the main artery and supply enough oxygenated blood to enable the cardiac tissue to survive and recover.
 
Collateral Circulation in the Venous System
Hepatic cirrhosis arising from chronic congestion in the hepatic portal vein may give rise to collateral circulation between branches of the portal and caval veins of the liver, or between the two caval veins. Consequences of newly established venous collaterals arising from portal hypertension include esophageal varices and hemorrhoids (porta-caval collateral circulation).
Q.3. Write short note on pulse points of head and neck.
(May 2014, 5 Marks)
Ans. Pulse points are those where the arterial pulse is felt. Following are the pulse points in head and neck:
  • Carotid pulse: Common or external carotid artery can be palpated in anterior triangle of neck. It is the strongest pulses in the body. Carotid pulse is obtained by palpating either the common carotid artery posterolateral to larynx or external carotid artery immediately lateral to pharynx midway between superior margin of thyroid cartilage below and greater bone of hyoid bone below.126
zoom view
Fig. 161: Pulse points of head and neck. Each pulse point is named after the artery it is associated with
  • Facial pulse: Facial artery can be palpated as it crosses inferior body of mandible immediately adjacent to anterior margin of masseter muscle.
  • Temporal pulse: Superficial temporal artery can be palpated anterior to ear and immediately posterosuperior to the position of temporomandibular joint. Anterior branch of superficial temporal artery can be palpated posterior to zygomatic process of frontal bone as it passes lateral to temporal fascia and into anterolateral region of scalp.
Q.4. Define end artery.
(Aug 2018, 1 Mark)
Ans. Arteries which do not anastomose with their neighbors are called end arteries.
127GENETICS
Q.1. Write a short note on Turner syndrome.
(Feb 2004, 5 Marks) (Aug 2012, 4 Marks)
(Dec 2011, 6 Marks)
Ans. Turner Syndrome
Turner syndrome is also known as Bonnevie-Ullrich syndrome or monosomy X or Ullrich-Turner syndrome.
  • The syndrome is named after Dr Henry Turner, who was one of the first to describe it, this is a genetic disease that effects the development of the body in females.
  • The disorder is caused by the complete or partial absence of one of the two X chromosomes.
 
Symptoms
As in many diseases of all types, symptoms between the individuals vary in severity and presence.
  • Most common deformity is short stature, starting out at birth and continuing for the rest of a individual's life
  • About 90% of women experience early ovarian failure, so that there are only enough hormones and egg cells produced by the ovaries so that only secondary sexual development occurs (poor breast development/ irregular nipple spacing, no menstruation)
  • Webbed neck (fold of skin stretching from the end of shoulder to the bottom of chin)
  • Small, narrow fingernails and toenails that turn up
  • Elbow deformity called cubitus valgus (arms that turn out slightly at the elbows)
  • Nevi (brown spots appearing sparatically on the skin)
  • Narrow, high-arched palate (roof of the mouth)
  • Retrognathia (receding lower jaw)
  • Low-set ears and low hairline
  • Slight droop to eyes
  • Strabismus (lazy eye)
  • Broad chest
  • Scoliosis (curvature of the spine)
  • Flat feet
  • Short fourth metacarpals (the ends of these bones form the knuckles)
  • Edema (fluid overload causing noticeable swelling) of hands and feet especially at birth
  • Cardiac abnormalities including hypertension (high blood pressure), dissection of the aorta, and a coarctation (narrowing) of the aorta and bicuspid aortic valve (a valve with two leaflets instead of the usual three)
  • Kidney problems that may result in urinary tract infections or an increased risk for hypertension
  • Hypothyroidism (low level of thyroid hormone) caused by autoimmune thyroiditis (inflammation of thyroid gland)
  • Otitis media (ear infection), mainly in early childhood or infancy.
  • Sensorineural (nerve) hearing loss.
zoom view
Fig. 162: Turner syndrome
 
Mental Problems
  • On an average, most turner syndrome females have an overall normal intelligence with a variance similar to that of the general population.
  • Spatial-temporal processing (imagining objects in relation to each other) difficulties.
  • Nonverbal memory complexities.
  • Attention difficulties.
These may cause further problems such as trouble with math, a poor sense of direction, little manual dexterity, and poor social skills.
 
Karyotype of Turner Syndrome
  • Turner syndrome is the monosomy of sex chromosome.
  • For Turner syndrome the karyotype is 45, XO which is the monosomy of X chromosome.
  • Here one chromosome is missing, so no Barr body is seen, though the individual is female.
Q.2. Write notes on Down syndrome.
(Mar 2006, 5 Marks) (Apr 2010, 5 Marks) (Dec 2010, 3 Marks)
(Sep 2013, 5 Marks) (Sep 2015, 5 Marks)
(Apr 2017, 4 Marks) (Jan 2018, 5 Marks)
128Ans. Down syndrome is also known as mongolism or trisomy 21.
  • Down syndrome is the most common congenital anomaly which occurs because of nuclear aberration of chromosomes.
  • Dr down describe this syndrome in 1866.
  • In down syndrome there is trisomy of chromosome 21. The number of chromosomes is 47, i.e. 47XX or 47XY. Sex can be either male or female. It is seen to occur as 1 in 700 newborn.
  • It is seen in elderly primigravida or mother suffering from viral infection during pregnancy.
  • In elderly primigravida the syndrome occur due to the aging of the ovum. Since sperms form fresh everytime, so aging factor is not applied for sperms.
  • Males are more commonly affected than females.
 
Clinical Features of Down Syndrome
  • Presence of mental retardation
  • Palpebral fissure slant upwards at lateral end
  • Protrusion of tongue out of the mouth
  • Presence of flat nasal bridge
  • On the eyes there is presence of epicanthic folds
  • Short broad hands with simian crease
  • Presence of small ears and small head circumference
 
Karyotype of Down's Syndrome
  • Trisomy of 21st chromosome most commonly leads to Down syndrome.
  • Karyotype in a trisomic Down is either 47 + XY or 47 + XX
  • Source of extra 21st chromosome is mostly from nondysjunction in maternal meiosis.
Q.3. Write a short note on Klinefelter syndrome.
(Dec 2012, 5 Marks) (Dec 2014, 5 Marks)
(Aug 2018, 5 Marks) (July 2016, 5 marks)
Ans. 47, XXY, or XXY syndrome is a condition in which human males have an extra X chromosome.
  • Females have an XX chromosomal makeup, and males an XY, affected individuals have at least two X chromosomes and at least one Y chromosome. Because of the extra chromosome, individuals with the condition are usually referred to as “XXY Males”, or “47, XXY Males”.
  • In humans, Klinefelter syndrome is the most common sex chromosome disorder and the second most common condition caused by the presence of extra chromosomes.
  • Affected males are almost always effectively infertile.
 
Features of Disease
  • Language learning impairment may be present.
  • In adults, possible characteristics vary widely and include little to no signs of affectedness, a lanky, youthful build and facial appearance, or a rounded body type with gynecomastia (increased breast tissue).
  • Individual has very small pair of testes but a normal penis and scrotum.
  • Secondary sexual characters do not develop fully and pubic and facial hair is scanty.
  • By adulthood, XXY males look similar to males without the condition, although they are often taller. They are also more likely than other men to have certain health problems, such as autoimmune disorders, breast cancer, vein diseases, osteoporosis, and tooth decay.
 
Karyotype of Klinefelter Syndrome
  • Cases of Klinefelter have karyotype of 47, XXY with some of the individuals showing mosaic pattern.
  • Here the individual is male with an extra X chromosome.
  • As there are two X chromosomes, one Barr body is present.
zoom view
Fig. 163: Klinefelter syndrome
Q.4. Write short note on karyotypes of Klinefelter and Turner syndrome.
(Sep 2017, 4 Marks)
Ans. Identification of chromosomes according to the length of arms including position of centromere is known as karyotyping.
 
Karyotype of Klinefelter's syndrome
  • Cases of Klinefelter have karyotype of 47, XXY with some of the individuals showing mosaic pattern.
  • Here the individual is male with an extra X chromosome.
  • As there are two X chromosomes, one Barr body is present.
 
Karyotype of Turner's Syndrome
  • Turner syndrome is the monosomy of sex chromosome.
  • For Turner syndrome the karyotype is 45, XO which is the monosomy of X chromosome.
  • Here one chromosome is missing, so no Barr body is seen, though the individual is female.
129NEUROANATOMY
 
1. INTRODUCTION TO BRAIN
Q.1. Write a short note on types of neurons.
(Sep 2006,5 Marks)
Or
Write short note on classification of neurons.
(May 2014, 5 Marks)
Ans. Neurons are of various types, according to the polarity, axon length, size and shape of neuronal cell body, i.e. soma
  1. Types according to number of their processes
    1. Multipolar neurons: In man most of the neurons are multipolar, e.g. all motor and internuncial nucleus.
    2. Bipolar neurons: These are confined to first neuron of retina, olfactory mucosa and ganglia of eight cranial nerve.
    3. Pseudounipolar neurons: These neurons are unipolar to begin with but they become bipolar functionally. These are found in dorsal nerve root ganglia and the sensory ganglia of cranial nerves.
    4. Unipolar neurons: They are seen in mesencephalic nucleus of trigeminal nerve and they also occur during the fetal life. These neurons are common in lower vertebrates.
  2. According to axon length
    1. Golgi type I: They consist of long axons and numerous short dendrites. They are seen in Purkinje cells of cerebellum, pyramidal cells of cerebellar cortex and anterior horn cells of spinal cord.
    2. Golgi type II: They consists of small axons, establish synapsis with neighboring neurons. They are seen in cerebral cortex and cerebellar cortex.
    3. Amacrine neurons without axon only with dendrite. They are seen in retina of eyeball.
  3. Functional classification
    Neurons are classified into sensory neurons, motor neurons and autonomic neurons, i.e. sympathetic and parasympathetic neurons.
    1. Sensory neurons: They are divided into three types
      1. Primary or first order sensory neurons: Present as spinal or sensory neurons in dorsal root ganglion of spinal nerves.
      2. Secondary or second order sensory neurons: Present in gray matter of spinal cord and brainstem.
      3. Tertiary or third order sensory neurons: Seen in thalamus.
    2. Motor neurons: Carry impulse from central nervous system to distal part of body. They are of two types:
      1. Upper motor neurons: Lie in motor area of brain
      2. Lower motor neurons: Lie in cranial nerve nuclei and anterior horn of spinal cord.
    3. Parasympathetic neurons:
      1. Preganglionic neurons are located in cranial nerves, i.e. III, VII, IX and X and in sacral 2–4 segments of spinal cord
      2. Postganglionic neurons are located close to wall or within wall of viscera.
      3. Parasympathetic outflow is known as craniosacral outflow.
    4. Sympathetic neurons
      1. Preganglionic neurons are located in lateral horn of T1 to L2 segments of spinal cord.
      2. Postganglionic neurons are located in ganglia of sympathetic trunk away from viscera.
      3. Sympathetic outflow is known as thoracolumbar outflow.
  4. Types according to shape of soma
    1. Stellate shape
    2. Fusiform shape
    3. Basket shape
    4. Pyramidal shape.
  5. According to size
    1. Microneurons: The length of soma is less than 7 µm
    2. Macro neurons: The length of soma is more than 7 µm.
 
2. MENINGES OF THE BRAIN AND CEREBROSPINAL FLUID
Q.1. Write short note on CSF.
(Jan 2012, 4 Marks)
Or
Write short note on CSF circulation.
(June 2010, 5 Marks)
Or
Write short answer on cerebrospinal fluid.
(Aug 2018, 3 Marks)
Ans. Cerebrospinal fluid (CSF) is the modified tissue fluid. CSF is contained inside the ventricular system of brain and in subarachnoid space around the brain and spinal cord.
CSF replaces lymph inside the central nervous system.
 
130Formation
  • Bulk of CSF is formed mainly by choroid plexus of lateral ventricles and in less amount by choroid plexus of third and fourth ventricles.
  • It is also formed by capillaries over surface of brain and spinal cord.
  • Total quantity of CSF formed is 150 mL. This is formed at the rate of 200 mL per hour or 5000 mL/day.
  • Normal pressure of CSF is 60 to 100 mm of water.
 
Circulation
CSF passes from each lateral ventricle to third ventricle via interventricular foramen of Monro. From third ventricle CSF passes to fourth ventricle via cerebral aqueduct. From fourth ventricle CSF passes to subarachnoid spaces of cerebrum and vertebral canal via median and lateral apertures of fourth ventricle. Some of CSF passes to central canal of spinal cord.
 
Absorption
  • CSF is absorbed chiefly via arachnoid villi and granulations, it is thus drained into cranial venous sinuses.
  • CSF is also absorbed partly by perineural lymphatics at around first, second and eighth cranial nerves.
  • CSF is also absorbed by veins which are related to spinal nerves.
 
Functions of CSF
  • It decreases sudden pressure or forces on delicate nervous tissue.
  • CSF nourishes nervous tissue. Only CEF comes in contact with neurons. It provides nourishment and return product of metabolism to venous sinuses.
  • Neurons cannot survive without glucose and oxygen for 3–5 minutes. Both glucose and oxygen are constantly supplied by CSF.
  • Pineal gland secretions reach to pituitary gland via CSF.
  • CSF cushion the brain within its solid vault. Both brain and CSF have same specific gravity, so brain simply floats in the fluid.
  • Since there is no CSF brain barrier, so drugs can reach to neurons via CSF.
  • Blood CSF barrier is present, so there are no antibodies in central nervous system which make infection of brain very serious.
zoom view
Fig. 164: Circulation of CSF as shown by white arrows
131Q.2. Describe briefly folds of dura mater.
(Apr 2008, 5 Marks)
Ans.
Name of the fold
Shape
Attachments to the fold
Venous sinus enclosed
Falx cerebri
This is of sickle shape and leads to the separation of right from the left cerebral hemisphere
  • Superiorly convex margins are attached to sides of groove lodging superior sagittal sinus
  • Inferiorly the concave margin is free
  • Anterior attachment is to cristae galli and posterior is to upper surface of tentorium cerebelli
  • Superior sagittal sinus
  • Inferior saggital sinus
  • Straight sinus
Tentorium cerebelli
This is of tent shape and separates cerebral hemispheres from hindbrain and lower part of midbrain. It lifts off the weight of occipital lobes from cerebellum
  • It consists of anterior free margin and its ends are attached to anterior clenoid processes. Rest of it is free and concave
  • Its posterior margin is attached to lips of groove which consists of transverse sinus, superior petrosal sinus and to posterior clinoid processes.
  • Transverse sinuses, superior petrosal sinus
Falx cerebelli
This is a small sickle shaped fold which partly separate two cerebellar hemispheres
  • Its base is attached to the posterior part of inferior surface of tentorium cerebelli
  • Occipital sinus
Diaphragma sellae
It is a small horizontal fold
  • Its anterior attachment is to tuberculum sellae
  • Its posterior attachment is to dorsum sellae; laterally continuous with dura mater of middle cranial fossa
  • Anterior and posterior intracavernous sinuses
 
Functions of Folds of Dura Mater
  • They divide cranial cavity into compartments to separate different parts of brain and restrict their movement in cranial cavity.
  • These folds enclose intracranial dural venous sinuses.
 
3. THE SPINAL CORD
Q.1. Write short note on lateral spinothalamic tract.
(Dec 2010, 3 Marks)
Ans. Origin: Laminae I to IV of spinal grey matter.
Beginning: From substantia gelatinosa of posterior gray column.
Termination: Area 3, 1, 2 of cerebral cortex.
Crossing over: Fibers cross in the corresponding spinal segment anterior to the central canal of spinal cord.
 
Course
First neuron fiber starts in dorsal root ganglia. They relay by synapsing with neurons which lie in the gray matter of lamina II and III. Pain fibers relay in lamina II. Second neuron fibers cross immediately to opposite sides close to central canal and ascend as tract in lateral white column of spinal cord. 3rd order neurons lie in the ventro-posterolateral nucleus of thalamus and axons of these neurons ascend through the internal capsule and then the thalamic radiations to area no. 3, 1, 2 of the cerebral cortex.
 
Function
It carry the sensation of pain and temperature from opposite half of the body.
zoom view
Fig. 165: Lateral spinothalamic tract
132Q.2. Describe spinal cord in detail.
(Aug 2011, 10 Marks)
Ans. Spinal cord is the long cylindrical lower part of central nervous system.
Spinal cord occupies upper two-third of the vertebral canal and is enclosed in three meninges.
Spinal cord is 45 cm in adult male and 42 cm in adult female. It extends from upper border of atlas vertebra to lower border of first lumbar vertebra. Superiorly it is continuous with medulla oblongata and inferiorly it terminate as conus medullaris. Conus medullaris is a lower tapering extremity. Apex of conus medullaris continue as thin thread like filament known as filum terminale.
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Fig. 166: Lateral view of spinal cord showing exit of emerging spinal nerves via intervertebral foramen
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Fig. 167: Parts of lower end of spinal cord
 
Meninges Covering Spinal Cord
Spinal cord is surrounded by three meninges, outer is dura mater, middle is arachnoid mater and inner one is pia mater. Spinal cord is enclosed only by meningeal layer of dura mater.
zoom view
Fig. 168: Meningeal coverings of spinal cord
133Spinal pia mater undergoes modification as:
  1. Ligamentum denticulatum with 21 pairs of teeth like projection which keep spinal cord in position.
  2. Linea splendens is the thickening seen at anteromedian sulcus.
 
External Features of Spinal Cord
External features of spinal cord are:
  1. Fissures and sulci.
  2. Attachment of spinal nerves.
  3. Enlargements.
  4. Cauda equina.
 
Fissures and Sulci
Anteriorly the spinal cord has a deep anterior median fissure which lodges the anterior spinal artery. Anterior median fissure is deep and extend along entire length of cord.
Posterior median sulcus is a thin longitudinal groove from which septum runs in depth of spinal cord.
Each half of spinal cord is subdivided into anterior, lateral and posterior region by anterolateral and posterolateral sulci. Anterolateral region give rise to motor root and posterolateral region give rise to sensory root.
 
Spinal Nerves
31 pairs of spinal nerves emerges from the side of cord. Out of these 8 are cervical, 12 are thoracic, 5 are lumbar, 5 are sacral and 1 is coccygeal. Cervical nerves leave vertebral canal above the corresponding vertebrae with the exception of 8th which emerges between C7 and T1 vertebrae. Remainder of spinal nerves emerges below corresponding vertebrae. Each spinal nerve is attached to the cord by two roots, i.e. motor root or anterior root and sensory root or posterior root.
 
Enlargements
Spinal cord presents fusiform swellings, i.e. cervical and lumbar enlargements.
Cervical enlargement extends from C5 to T1 whereas lumbar enlargement extends from L2 to S3 spinal segements.
 
Cauda Equina
Since spinal cord is shorter than vertebral column, length and obliqueness of spinal nerve roots increases from above to downwards. As a result the nerve roots of lumbar, sacral and coccygeal nerves from caudal part of cord take vertical course and form bunch of nerve fibers around filum terminale which is known as cauda equina. It is so called because of its resemblance to horse of tail.
 
Internal Structure of Spinal Cord
Cross-section of spinal cord shows that it consists of inner core of grey matter and peripheral zone of white matter.
White matter lies outside and gray matter lies inside. In the center of gray matter is the central canal which consists of CSF.
 
Gray Matter
  • Gray matter is in the shape of H with gray commissure joining gray matter of right and left sides.
  • Gray matter consists of one posterior horn and one anterior horn on each side.
  • In T1-L2 and S2-S4 segments an additional horn is present which is known as lateral horn.
  • Structure of gray matter consists of nerve cells, neuroglia and blood vessels.
 
White Matter
  • White matter of spinal cord surrounds the central shaped mass of gray matter and it mainly consists of nerve fibers.
  • The majority of nerve fibers are myelinated and provide white appearance to white matter.
 
Tracts of Spinal Cord
There are three types of tracts present descending, ascending and intersegmental:
  1. Descending tracts or motor tracts: They conduct impulses to spinal cord from the brain. Descending tracts are divided into pyramidal tracts, i.e. lateral corticospinal tract, anterior corticospinal tract and extrapyramidal tracts, i.e. rubrospinal, tectospinal, lateral vestibulospinal, olivospinal, medial and lateral reticulospinal.
  2. Ascending tracts or sensory tracts: They conduct impulses from periphery to brain through the spinal cord. The ascending tracts are lateral spinothalamic, anterior spinothalamic, fasciculus gracilis, fasciculus cuneatus, dorsal spinocerebellar, ventral spinocerebellar.
    For diagram of ascending and descending tracts refer to Ans 5 of same chapter.
  3. Intersegmental tracts: These are short ascending and descending tracts which originate and end in spinal cord. They are present in anterior, posterior and lateral columns of white matter. These tracts interconnect the neurons of different segmental levels. The intersegmental tracts are dorsolateral fasciculus, septomarginal and comma tract.
 
Arterial Supply of Spinal Cord
Spinal cord is supplied by:
  • Anterior spinal artery
  • Two posterior spinal arteries
  • Segmental arteries.
Anterior spinal artery supplies the anterior two-third of cord while the two posterior spinal arteries together supplies posterior one-third of the cord.
Segmental arteries along with anterior and posterior spinal arteries form arterial trunks which communicate around a cord and form plexus known as arteriae coronae. This corona provides peripheral branches which supply to superficial region of spinal cord.134
zoom view
Fig. 169: Arterial supply of spinal cord: A. Anterior view, B. Posterior view
zoom view
Fig. 167: Venous drainage of spinal cord
 
Venous Drainage
Veins draining the cord form six longitudinal venous channels around the cord, i.e.
  • Two median longitudinal, one in the anterior median fissure and other in the posteromedian sulcus.
  • Two anterolateral, one on either side, posterior to the anterior nerve roots.
  • Two posterolateral, one on either side posterior to the posterior nerve roots.
 
Function of Spinal Cord
  • Execution of simple reflexes
  • Transmission of impulses to and from the brain.
Q.3. Describe briefly spinal cord.
(Feb 2013, 5 Marks) (May/June 2009, 5 Marks)
Ans. Refer to Ans 2 of same chapter.
Q.4. Write short note on radicular artery.
(Sep 2011, 5 Marks)
Ans. Radicular artery is derived from various parent like spinal branches of the vertebral, ascending cervical, deep cervical, intercostals, lumbar and sacral arteries.135
zoom view
Fig. 171: Radicular arteries
  • There are 8 anterior and 12 posterior radicular arteries which reaches the spinal cord.
  • Radicular arteries are regular serial enforcements to spinal arteries.
  • As fetus grow most of the radicular artery disappear, those that remain, form anastomoses with the anterior and posterior spinal arteries and are commonly known as booster or feeder vessels. The most largest of the feeder vessels is arteria radicularis (magna of Adamkiewicz).
  • Many of these radicular artery branches are small and are end by feeding the nerve roots. Few of them which are large and contribute blood to the spinal arteries.
  • One of the anterior radicular branches are very large and is called the arteria reticularis magna. Its position is variable. This artery may be responsible for supplying blood to as much as the lower two-third of the spinal cord.
  • The function radicular artery is to make contributions to reinforce the longitudinal trunks.
Q.5. Write short note on lumbar puncture.
(May 2014, 5 Marks)
Ans. Lumbar puncture is done for withdrawing cerebrospinal fluid for various diagnostic and therapeutic purposes.
  • At the time of lumbar puncture a horizontal line is drawn which joins the highest points of iliac crest and the line passes via spine of L4 vertebrae. Now the interpinous spaces above and below this landmark are used with safety.
  • Lumbar puncture should be done below termination of spinal cord, i.e. lower border of L1 but the most preferred site is interspinous space between L3 and L4. (See Fig. 172)
  • During lumbar puncture spine must be fully flexed with patient either lying or seated on the side.
  • Needle is passed inward and somewhat cranially exactly in the midline, supraspinous and interspinous ligaments are traversed and dura matter is penetrated with a distinct feel of ‘give way’.
Q.6. Describe spinal cord and draw TS at midcervical region.
(Dec 2014, 10 Marks)
Ans. For description of spinal cord refer to Ans 2 of same chapter.
TS at Midcervical Region
(See Fig. 173)
Q.7. Write short note on corticospinal tract.
(Apr 2007, 5 Marks)
Or
Write briefly on pyramidal tract.
(Dec 2010, 5 Marks)
Ans. Corticospinal tract is also known as pyramidal tract.
Origin: Most of the fibers of corticospinal tracts originate from pyramidal cells of motor area of cerebral cortex. Some of the fibers originate from other parts of cortex.
Course: Fibers of corticospinal tract pass through corona radiata, internal capsule, crus cerebri of cerebral peduncles, ventral part of pons and pyramid of medulla oblongata.136
zoom view
Fig. 172: Lumbar puncture
zoom view
Fig. 173: Transverse section at midcervical region
In the lower part of medulla majority of fibers cross to the opposite side at pyramidal decussation of medulla and descend in lateral white column of spinal cord as lateral corticospinal tract. Lateral corticospinal tract consists of some fibers which arise from ipsilateral cerebral cortex. Lateral corticospinal tract is located in lateral white column in front of posterior horn and medial to posterior spinocerebellar tract.
Uncrossed fibers descend in anterior white column of spinal cord as anterior corticospinal tract. Anterior corticospinal tract is located in anterior white column close to anterior median fissure.
At the lower level fibers of anterior cor