Anatomy: Anatomical Position and Directional Terms

Anatomical Position

• The standard anatomical position is the fundamental reference point for describing the location of body structures.
• The body is upright, facing forward, with the arms at the sides, and the palms and toes facing forward.
• This consistent reference position ensures that anatomical descriptions are unambiguous.

Directional Terms

• These terms describe the relative position of one body part to another, allowing for clear communication about locations within the body.
  • Superior: Toward the head or upper part of the body. (e.g., the head is superior to the chest)
  • Inferior: Away from the head or toward the lower part of the body. (e.g., the stomach is inferior to the lungs)
  • Anterior (ventral): Toward the front of the body. (e.g., the breastbone is anterior to the spine)
  • Posterior (dorsal): Toward the back of the body. (e.g., the shoulder blades are posterior to the ribcage)
  • Medial: Toward the midline of the body. (e.g., the heart is medial to the lungs)
  • Lateral: Away from the midline of the body. (e.g., the arms are lateral to the chest)
  • Proximal: Closer to the origin of the body part or the point of attachment of a limb to the trunk. (e.g., the elbow is proximal to the wrist)
  • Distal: Farther from the origin of a body part or the point of attachment of a limb to the trunk. (e.g., the fingertips are distal to the elbow)
  • Superficial: Toward or at the body surface. (e.g., the skin is superficial to the muscles)
  • Deep: Away from the body surface; more internal. (e.g., the bones are deep to the skin)

Body Planes

• Planes are imaginary flat surfaces used to section the body for anatomical study.
  • Sagittal plane: Divides the body into right and left portions.
    • Midsagittal (median) plane: Divides the body into equal right and left halves.
    • Parasagittal plane: Divides the body into unequal right and left portions.
  • Frontal (coronal) plane: Divides the body into anterior (front) and posterior (back) portions.
  • Transverse (horizontal) plane: Divides the body into superior (upper) and inferior (lower) portions.

Body Cavities

• Body cavities are spaces within the body that house vital organs.
  • Dorsal cavity: Located near the back of the body.
    • Cranial cavity: Contains the brain.
    • Vertebral (spinal) cavity: Contains the spinal cord.
  • Ventral cavity: Located near the front of the body.
    • Thoracic cavity: Contains the heart, lungs, and other structures.
      • Pleural cavities: Surround the lungs.
      • Pericardial cavity: Surrounds the heart.
    • Abdominopelvic cavity: Contains the digestive organs, reproductive organs, and urinary bladder.
      • Abdominal cavity: Contains stomach, intestines, liver, and other digestive organs.
      • Pelvic cavity: Contains urinary bladder, portions of the large intestines, and internal reproductive organs.

Body Regions

• Sectionsing the body into regions helps to precisely locate and describe the relative positions of body structures related to specific regions.
  • Common anatomical regions include:
    • Head: Includes the skull and face.
    • Neck: Connects the head to the trunk.
    • Trunk: Includes the chest, abdomen, and back.
    • Upper limbs: Arms, forearms, wrists, and hands.
    • Lower limbs: Thighs, legs, ankles, and feet.