Describe the appendicular skeleton
The appendicular skeleton is the portion of the skeleton that includes the bones of the limbs and the girdles that attach them to the axial skeleton. It is composed of the bones of the upper limbs, lower limbs, shoulder girdle, and pelvic girdle.
The upper limb includes the bones of the arm, forearm, wrist, and hands. It consists of the humerus, radius, ulna, carpals, metacarpals, and phalanges. The humerus is the long bone of the upper arm, while the radius and ulna are the bones of the forearm. The carpals, metacarpals, and phalanges make up the bones of the wrist and hand.
The lower limb comprises the bones of the thigh, leg, ankle, and foot. It includes the femur, patella, tibia, fibula, tarsals, metatarsals, and phalanges. The femur is the longest and strongest bone in the body and forms the thigh. The patella, commonly known as the kneecap, is located on the front of the knee joint. The tibia and fibula are the bones of the leg, with the tibia being the larger and stronger bone. The tarsals, metatarsals, and phalanges form the bones of the ankle and foot.
The shoulder girdle consists of the clavicle and scapula, which connect the upper limb to the axial skeleton. The clavicle is commonly known as the collarbone and runs horizontally across the front of the shoulder. The scapula, or shoulder blade, is a flat, triangular bone located on the back of the shoulder.
The pelvic girdle includes the bones of the hip and pelvis. It consists of two hip bones, each composed of three fused bones: the ilium, ischium, and pubis. The hip bones articulate with the sacrum, a bone in the axial skeleton, to form the sacroiliac joints.
Overall, the appendicular skeleton provides support, stability, and attachment for the muscles of the limbs, allowing for movement and mobility in humans.