Anatomical Terminology and Body Organization

Anatomical Position

  • Standard reference position:
    • Body is erect.
    • Feet are slightly apart.
    • Palms face forward.

Regional Terms

  • Divisions of the body:
    • Axial: Head, neck, and trunk.
    • Appendicular: Limbs (attached parts).

Orientation and Directional Terms

  • Superior (cranial): Toward the head; above.
  • Inferior (caudal): Away from the head; below.
  • Ventral (anterior): Toward the front of the body; in front of.
  • Dorsal (posterior): Toward the back of the body; behind.
  • Medial: Toward the midline; on the inner side.
  • Lateral: Away from the midline; on the outer side.
  • Intermediate: Between a more medial and a more lateral structure.
  • Proximal: Closer to the origin of the body part or point of attachment.
  • Distal: Farther from the origin of the body part or point of attachment.
  • Superficial (external): Toward or at the body surface.
  • Deep (internal): Away from the body surface; more internal.

Body Planes

  • Flat surfaces used for anatomical study. There are three main types:
    • Sagittal plane: Divides body vertically into right and left parts.
      • Midsagittal (median) plane: Lies on the midline.
      • Parasagittal plane: Not on the midline.
    • Frontal (coronal) plane: Divides body vertically into anterior and posterior parts.
    • Transverse (horizontal) plane: Divides body horizontally into superior and inferior parts; produces a cross section.

Body Cavities

  • Dorsal Cavity: Protects the nervous system.
    • Cranial cavity: Encases the brain.
    • Vertebral cavity: Encases the spinal cord.
  • Ventral Cavity: Houses internal organs (viscera); separated from the dorsal cavity by the diaphragm.
    • Thoracic cavity: Houses heart and lungs.
      • Two pleural cavities: Each houses a lung.
      • Mediastinum: Central compartment containing pericardial cavity, surrounding thoracic organs.
      • Pericardial cavity: Encloses the heart.
    • Abdominopelvic cavity:
      • Abdominal cavity: Contains stomach, intestines, spleen, liver.
      • Pelvic cavity: Contains urinary bladder, reproductive organs, rectum.

Serous Membrane (Serosa)

  • Thin, double-layered membrane separated by serous fluid.
    • Parietal serosa: Lines internal body walls.
    • Visceral serosa: Covers internal organs.
    • Serous fluid: Allows organs to slide without friction.
  • Body can be divided into 99 abdominopelvic regions and 44 abdominopelvic quadrants.

Other Body Cavities

  • Oral and digestive cavities
  • Nasal cavity
  • Orbital cavities
  • Middle ear cavities
  • Synovial cavities (joint cavities)