INTRODUCTIONrnThe upper part of the temporomandibular joint (TMJ) is formed by the temporomandibular fossa or glenoid fossa, and the lower part is formed by the mandibular condyle. An ellipsoidal articular disc composed of fibrous connective tissue divides the joint into two parts:the upper and the lower articular cavities. These cavities are limited by the synovial membrane and filled with fluid.