Temporomandibular Joint (TMJ) Anatomy

Temporomandibular Joint elements.

Top, The temporomandibular joint (TMJ) is formed at the meeting point of the temporal bone, which is part of the cranium (skull), and the lower jaw bone, called the mandible.

Bottom, The articular disc, which divides the joint into two, is composed of fibrocartilaginous tissue positioned between the two bones that form the joint. The TMJ is one of the few synovial joints in the human body with an articular disc. The lower joint compartment formed by the mandible and the articular disc is involved in rotational movement, the initial movement of the jaw when the mouth opens. The upper joint compartment formed, by the articular disc and the temporal bone, is involved in translational movement, the secondary gliding motion of the jaw as it is opened widely. The condyle is the undersurface facets formed where the mandible meets the bottom surface of the disc. The glenoid (or mandibular/articular) fossa is the portion of the temporal bone which mates to the upper surface of the disc.