The Skeletal System: Bones and Joints

The adult human skeleton consists of 206 bones organized into the axial skeleton (skull, vertebral column, thoracic cage) and the appendicular skeleton (limbs and limb girdles).

Bones are classified by shape: long bones (femur, humerus), short bones (carpals, tarsals), flat bones (cranial bones, scapula), irregular bones (vertebrae), and sesamoid bones (patella).

Bone tissue is dynamic, constantly being remodeled by osteoblasts (bone formation) and osteoclasts (bone resorption). This process responds to mechanical stress (Wolff's law), hormonal signals, and nutritional factors.

Joints (articulations) are classified by structure and function. Synovial joints are the most common and mobile type, featuring a joint capsule, synovial membrane, and articular cartilage. Types include hinge, pivot, ball-and-socket, saddle, condyloid, and gliding joints.