Anatomy, Appendicular Skeleton

Excerpt

The appendicular skeleton is 1 of 2 major bone groups in the body, the other being the axial skeleton (see Image. Appendicular Skeleton). The appendicular skeleton comprises the upper and lower extremities. The shoulder and hip are important limb segments connecting the appendicular and axial skeleton, essential for mechanical load transfer.

Of the 206 bones in the adult human body, 126 form the appendicular skeleton. A single upper extremity is composed of 14 phalanges (proximal, intermediate, and distal), 5 metacarpals, 8 carpals, 2 forearm bones (radius and ulna), the humerus, and the shoulder girdle (scapula and clavicle). A single lower extremity contains 14 phalanges (proximal, intermediate, and distal), 5 metatarsals, 7 tarsal bones, 2 leg bones (fibula and tibia), the femur, and the hip (ilium, ischium, and pubis).

Many ligaments, cartilage, and tendons strengthen bone articulations within the appendicular skeleton. Bony prominences and protuberances serve as muscle attachment sites. The appendicular skeleton is specialized for enhanced mobility and locomotion compared to the axial skeleton.