A radiographic and histologic study of the topographic relations in the temporomandibular joint region: implications for a nerve entrapment mechanism.

A radiographic and histologic investigation was performed in 18 temporomandibular joint (TMJ) autopsy specimens. Disc position was determined arthrotomographically. The pathway of the nerve branches in the vicinity of the joint was reconstructed from serial sagittal or frontal histologic sections. The relationship between the joint components and the different nerves running in the vicinity of the joint was studied. The results revealed the existence of topographical prerequisites for mechanical influence upon the nerve branches passing in the TMJ region. In two joints, both with a displaced disc, the auriculotemporal nerve trunk was almost in contact with the medial aspect of the condyle instead of having its normal sheltered course at the level of the condylar neck, thus exposing the nerve to the risk of mechanical irritation during condylar movements in an anteromedial direction. Two joints with normal disc position had an extension of the medial fossa wall in a caudal direction. In these joints the auriculotemporal nerve had its course between the condyle and the elongated fossa wall, exposing it to the risk of mechanical irritation during medial disc displacement. Compression of the masseteric nerve anterior to the TMJ was found in one joint with excessive condylar translation. The deep posterior temporal nerves may pass close to the anterior insertion of the joint capsule on the temporal bone, exposing them to the risk of mechanical irritation when there is condylar hypermobility. It was also found that the inferior alveolar and the lingual nerves may pass close to the medial part of the condyle. In joints with this nerve topography, a medially displaced disc could interfere mechanically with these nerves. These findings could offer an explanation for the sharp, shooting pain felt locally in the joint with jaw movements and the pain and other sensations projecting to the terminal area of distribution of the nerve branches in the vicinity of the TMJ such as the ear, temple, cheek, tongue, and teeth.