Joint, in anatomy, junction or union between two or more bones, especially one in which bones move. Generally speaking, three kinds of junctions can be distinguished. A fibrous junction consists of connective tissue; almost no movement is possible in this type of joint. A cartilaginous junction is composed of cartilage; here only moderate movement is possible. The synovial junction is the most familiar type of joint. Here the extremities of the facing bones are covered with a thin layer of smooth cartilage, separated from each other by synovial fluid. This kind of joint permits the greatest amount of movement. The type of movement possible depends on the type of joint. Some examples are the hinge (knee and elbow), the pivot (neck and skull connection), and the ball and socket (hip and shoulder).
See also: Bone.