The lining membrane of a joint cavity.
A layer of cells that form a membrane to line the inner surfaces of a joint. The synovial membrane secretes synovial fluid that fills and lubricates the joint space. This fluid is essential to proper functioning of the joint and aids in the movement of joints, supplies nutrients and oxygen to the joint tissues, destroys foreign matter in the blood and tissues of a joint, and fights infection.
The synovium is the tissue that lines the capsule surrounding a movable joint. It also provides a protective sheath for specific tendons in the hands and feet. This membrane produces synovial fluid, which serves to lubricate either the joint or the tendon. Inflammation of the synovium within a joint is termed synovitis, whereas inflammation occurring in a tendon sheath is called tenosynovitis.