Anatomic Divisions and Terms

The 206 bones of the body divide into two major groups

  • Axial bones – comprise the vertical axis of the skeleton; 80 bones.
  • Appendicular bones – bones that append (aka attach) to the axial skeleton; 126 bones.

Anatomical position

  • The vertebral column is vertical, the arms are extended with palms facing anteriorly, and the legs are extended with toes pointing anteriorly (towards the front of the body).

Axial skeleton

Skull

  • Encloses and protects brain

Hyoid bone

  • U-shaped bone; muscles of speech and swallowing attach to the hyoid bone

Vertebral column

Bones of the spine, terminates in the sacrum

Thoracic cage

  • Sternum – breast bone
  • Ribs – form the lateral walls of the thoracic cage

Appendicular skeleton

Pectoral girdle

  • Comprises the scapula (aka shoulder blade), which articulates with the humerus; and, the clavicle, which articulates with the sternum and scapula

Arm

  • The humerus articulates with the scapula

Forearm

  • The radius (laterally)
  • The ulna (medially)

Hand

  • Carpals (wrist)
  • Metacarpals (palm)
  • Phalanges (fingers)

Pelvic girdle

  • Bilateral os coxa bones (aka hip bone), articulate with the sacrum posteriorly

Thigh

  • Femur (aka thigh bone) articulates with the lateral side of the coxal bone; it is the longest and strongest bone in the body

Leg

  • Fibula, laterally; very slim, attachment site for muscles
  • Tibia, medially (“shin” bone); thick, weight-bearing bone of the leg

Kneecap

  • Patella; encased within tendons that pass over the knee, so is a sesamoid bone

Foot

  • Tarsals (ankle)
  • Metatarsals (foot base)
  • Phalanges (toes)

Directional nomenclature

Proximal

  • Closer to the center of the body or limb attachment

Distal

  • Further from the center of the body or limb attachment

Contralateral

  • On opposite sides of the body

Ipsilateral

  • On same side of the body

Intermediate

  • A structure between two others

Superior

  • Towards the top of the head

Inferior

  • Towards the feet

Medial

  • Towards the midline of the body

Lateral

  • Away from the midline of the body

Sagittal plane

  • Divides body into right and left sides

Transverse plane

  • Divides body into superior and inferior divisions

Superficial

  • Structure that is close to the surface of the body

Deep

  • A structure that is near the center of the body

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