Jaw muscle attachments to the temporomandibular joint: Some anatomical and pathophysiological considerations

Although the form and function of the articular disc and capsular tissues of the temporomandibular joint (TMJ) have been well described, the clinical anatomy and neuromuscular physiology of the various muscle and medial ligamentous attachments to the disc-capsule complex of the TMJ are poorly understood. Pathophysiological concepts have been proposed in relation to these articular attachments but they lack supporting evidence and are often based on theoretical constructs of clinical anatomy rather than anatomical research. In this presentation dissection observations on the articular attachments of the TMJ and the anatomy and innervation of the temporomasseteric complex – documented as part of research for a doctoral thesis entitled ‘The anatomy of the infratemporal fossa: dissections and historical representations’ (The University of Sydney, under the supervision of Professor Iven Klineberg and submitted in 2000) – are discussed in the context of both the historical and contemporary anatomical literature.

Dissection observations in this research project confirmed that fine fibrous septa from the perimysium of the deep masseter and posterior temporalis muscles were inserted into the antero-lateral aspect of the disc-capsule complex of the TMJ, although the particular temporalis and masseter muscle fibre bundles associated with these articular attachments, were neither as extensive nor demarcated as sometimes reported. A temporomasseteric complex (TMC) – formed by the interlacing of postero-medial masseter muscle fibres with fleshy postero-lateral temporalis fibre bundles, originating from tendinous attachments to posterior temporalis as well as the deep temporalis fascia – was consistently found.

The masseteric component of the TMC was innervated by branches of the temporomasseteric nerve trunk (TMNT) and the superior division of the masseteric nerve, while the temporal component was innervated by branches of a deep temporal nerve (DTN), which arose from the TMNT or plexus, traversed (postero-laterally) the infratemporal crest – where it was bound to periosteum by a discrete fascial band – and passed posteriorly in close association with the posterior temporalis tendon. This nerve was distinguished from the classically described posterior DTN, which is not tightly bound to periosteum and passes supero-laterally over the infratemporal crest. A revised classification of the DTNs is proposed to accommodate the dissection observations in this research.