Dislocation of jaw

Displacement of the mandible, the largest and strongest bone of the face constituting the lower jaw. Dislocation of the temporomandibular joint is a painful condition that occurs when the mandibular condyle becomes fixed in the anterosuperior aspect of the articular eminence.

TMJ dislocation is due to either trauma or, more commonly, excessive opening of the mandible. Spasm of the masseter, temporalis, and internal pterygoid muscles results in trismus, preventing return of the condyle to the temporal fossa.