Perspectives on the role of the lateral pterygoid muscle and the sphenomandibular ligament in temporomandibular joint function.

The lateral pterygoid muscle plays an important role in the movement of the mandible and has been studied from several points of view, including structural and functional anatomy. What matters clinically is the relative position of the muscle fibers attached medially to the mandibular condyle. In the following study, we observed not only the attachment of the lateral pterygoid muscle fibers to the articular disk, but also the relative position of the mandibular condyle to a base line set up on the mandibular condyle. According to our observations, the lateral pterygoid muscle fibers attach to the articular disk at the inner point of the medial pole. Based on this finding, we can say that the muscle fibers can both draw the articular disk anteriorly and balance it by supporting it posteriorly. That is to say, the lateral pterygoid muscle has two actions: to elevate the articular disk anteriorly and to support the articular disk. Furthermore, the sphenomandibular ligament has continuity with the articular disk tissue medially. This relationship suggests that the ligament fibers attached to the articular disk draw the disk posteriorly in its course of mandibular closing, thus enabling the articular disk to move smoothly.