Essentials of Human Anatomy BK Tandon
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ONE
Introduction to Anatomy

The BasicsCHAPTER 1

The term ‘Anatomy’ is derived from Greek word anatome (= cutting up). Anatomy, therefore, is the study of structure of human body after dissection. Human anatomy is the oldest medical science. The first person to describe the structure of human body was the Greek philosopher, Aristotle, nearly 2,300 years ago.
 
THE SUBDIVISIONS OF ANATOMY
  1. Gross-anatomy: Macroscopic study of human body after dissection. It can be studied as:
    1. Systemic (Systematic) anatomy: Study of different systems of the body:
      • Osteology: Study of the bones
      • Arthrology: Study of the joints
      • Myology: Study of the muscles
      • Angiology: Study of the cardiovascular system
      • Splanchnology: Study of the internal organs
      • Neurology: Study of the nervous system
      • Endocrinology: Study of the endocrines or the ductless glnds
      • Integumentary system: Study of the skin and its derivatives.
    2. Regional anatomy: Study of the different regions of human body:
      • Head and neck
      • Brain
      • Thorax
      • Abdomen and pelvis
      • Upper extremity
      • Lower extremity.
  1. Microscopic anatomy (Histology): Study of the minute structure of the body with the help of a microscope.
  2. Developmental anatomy (Embryology): Study of the embryo and fetus within the uterus or the womb.
  3. Applied anatomy (Clinical anatomy): Study of those aspects of anatomy which are applicable to the clinical disciplines and help to explain and provide a background for the clinical signs and symptoms.
  4. Functional anatomy: Study of structure of different parts of the body related to their functions.
  5. Surface anatomy: Study of the landmarks, e.g. bony prominences and muscular elevations, and projections of outlines of viscera and other structures on the surface of the body.
  6. Radiological anatomy: Study of different parts of body, specially bones and joints, with the help of X-rays.
 
THE POSITIONS OF THE BODY
  1. The anatomical position: The body is standing erect with arms by the sides and palms facing forwards. The legs and feet are together and eyes look directly to the front.2
    All the structures of human body are described with reference to the anatomical position.
  2. The supine position: The body is in lying down position with the back touching the surface and the front of the body facing upwards.
  3. The lithotomy position: The upper part of the body is lying in supine position with the back touching the surface. Both lower limbs are flexed and abducted at hip joints and flexed at the knee joints.
    This position of the body is used for
    • Child birth
    • Operations in the pelvic and perineal regions
    • Dissection of the perineal and pelvic regions in the cadavers.
 
THE PLANES OF THE BODY
  1. The median sagittal (median) plane: It is the vertical plane passing through the center of the body and dividing the body into two equal halves—right and left.
  2. The sagittal (para-sagittal) plane: It is the vertical plane that lies parallel to the median sagittal plane.
  3. The coronal plane: It is the vertical plane that is placed perpendicular to the sagittal planes.
  4. The transverse (horizontal) plane: It is the horizontal plane that lies perpendicular to the sagittal and coronal planes.
 
THE DESCRIPTIVE ANATOMICAL TERMS
  1. Anterior-posterior
    • Anterior (ventral) is towards the front of the body.
    • Posterior (dorsal) is towards the back of the body.
  2. Superior-inferior
    • Superior (upper) is towards the head end of the body.
    • Inferior (lower) is towards the foot end of the body.
  3. Medial-intermediate-lateral
    • Medial is nearer the median plane of the body.
    • Intermediate is in between medial and lateral.
    • Lateral is away from the median plane of the body.
  4. Cranial-caudal
    • Cranial is towards the head end of the body.
    • Caudal is towards the lower end of the trunk or cauda (tail)
      These terms are used in cases of embryo and fetus usually.
  5. Proximal-distal
    • Proximal is closer to the median plane of the body or the origin of the structure.
    • Distal is farther from the median plane of the body or the origin of the structure.
  6. Superficial-deep
    • Superficial (external) is closer to the surface of the body.
    • Deep (internal) is farther from the surface of the body.
  7. Palmer-plantar
    • Palmer refers to the ventral aspect of the hand.
    • Plantar refers to the sole of the foot.
  8. Peripheral-central
    • Peripheral is away from the median plane of the body.
    • Central is closer to the median plane of the body.
 
THE TERMS RELATED TO THE MOVEMENTS
The movements take place mostly at various joints of the body and are responsible for changing position of diferent parts of the body.
  1. Flexion-extension takes place at the transverse axis of the joint.
    • Flexion is the angular movement which consists of bending at the joint.
    • Extension is the straightening movement, whereby a joint is made straight.3
  2. Abduction-adduction takes place at an antero-posterior axis of the joint.
    • Abduction is the movement of the joint away from the median plane of the body or a fixed axis.
    • Adduction is the opposite movement towards the median plane of the body or a fixed axis.
  3. Circumduction is combined movement of flexion—extension and abduction—adduction at a joint. This movement is possible only in very mobile joints, e.g. shoulder joint and hip joint.
  4. Medial rotation-lateral rotation takes place at the vertical axis of the joint.
    • Medial rotation consists of rotating the ventral surface of the part towards the median plane.
    • Lateral rotation consists of rotating the ventral surface of the part away from the median plane.
  5. Elevation-depression
    • Elevation is the movement whereby the part is raised towards the head end of the body.
    • Depression is the movement of lowering the part towards the foot end of the body.
  6. Protraction-retraction
    • Protraction is moving a joint or a structure towards the front of the body.
    • Retraction is moving a joint or a structure backwards.
  7. Inversion-eversion
    • Inversion is the movement of rotating the foot so that sole faces inwards.
    • Eversion is the movement of rotating the foot so that the sole faces outwards.
      These movements occur in relation to the foot only.
  8. Pronation-supination
    • Pronation is the movement of rotating the forearm and hand so that the front of the forearm and palm faces backwards.
    • Supination is the opposite movement of rotating the forearm and hand so that the front of the forearm and palm face forwards.
      These movements occur in relation to the forearm and hand only.
Most of the anatomical names are derived from the Latin and Greek languages. There are nearly 5,000 terms in anatomy, which are used for naming the structures. These terms were adopted at a meeting of the German Anatomical Society, held at Basle in the year 1895. Therefore, these terms are called BNA (Basle Nomina Anatomica). These terms are universally accepted all over the world.
Subsequently, some revisions were made at the Fifth International Congress of Anatomists held at Oxford in the year 1950. In the meeting a new body called International Anatomical Nomenclature Committee has been formed for subsequent revisions of terms.