TMJ Biomechanics and Structure of the Mandibular Condyle

The TMJ, a structurally and functionally complex unit, is enclosed in an articular capsule, which extends from the articular eminence and mandibular fossa superiorly to the neck of the mandibular condyle inferiorly. The condyle is covered and protected by the TMJ disc as the disc slides between the mandibular fossa and articular eminence with joint movement. The presence of the TMJ disc reduces the shape and size incongruence between the condyle and the articular eminence because the disc's biconcave surfaces conform to the shapes of these articulating structures. Furthermore, the TMJ disc separates the articular capsule into superior and inferior joint compartments. The disc is held in place by the disc attachments to the mandibular condyle and the superior belly of the lateral pterygoid muscle. These anatomical structures facilitate a seamless articulation in the biomechanically demanding TMJ.