joint

The junction of two or more bones; an articulation. The joint is an anatomical structure that constitutes a functional unit biologically and biomechanically. It is composed of cartilage-lined extremities of the articulating bones (see articular cartilage), a layer of bone directly beneath the cartilage (known as the subchondral layer), a fibrous capsule with ligaments, and the joint capsule and associated musculature. The different parts of a joint are functionally interdependent; damage to one part usually affects all other parts. See also amphiarthrosis, ball-and-socket joint, condyloid joint, gliding joint, hinge joint, pivot joint, saddle joint, synarthrosis, syndesmosis, synovial joint.