Structural and functional basis for internal derangement of the temporomandibular joint: a histological investigation

Recent years have seen increased interest in treating temporomandibular joint (TMJ) disorders. Much therapy, both surgical and non-surgical, has been based on assumptions of anatomy largely defined by gross dissection studies with insufficient level of detail to illustrate its intricacy. This study defines the insertion of the superior head of the lateral pterygoid (SLP) muscle. Twenty-five cadaveric joints were retrieved en bloc and sectioned parasagittally. Histologic sections were taken every 100-200 µm, stained using the Masson trichrome technique, and examined for muscular insertion. Results showed that very little of the SLP muscle appears to insert into the disc; rather, the majority of the insertion was into the condylar neck at the pterygoid fovea. It was noted that only a few specimens demonstrated any appreciable number of fibres inserting into the disc. These observations provide further context in the consideration of treatment options for management of anterior disc displacement of the TMJ.