Temporomandibular joint innervation: Anatomical study and clinical implications.

BACKGROUND: Temporomandibular disorders and related pain are commonly seen in clinical practice. Due to its recurrent nature, they adversely affect a patient's social life. Current knowledge on the temporomandibular joint (TMJ) innervation is debatable and insufficient to ensure optimal treatment for the underlying pathology. This study aimed to elucidate the pathophysiology of temporomandibular pain by revealing the TMJ innervation topography, its variations, and its relationships with the surrounding anatomical structures. This will aid in creating a guide for temporomandibular, infratemporal, and preauricular interventions. METHODS: A total of 20 cadaver half heads, 10 fresh frozen and 10 embalmed, were used. The TMJ nerves were dissected together with the surrounding anatomical structures. RESULTS: We showed that the TMJ is mainly innervated by the auriculotemporal nerve posteriorly, the masseteric nerve anteriorly, the posterior deep temporal nerve anteromedially, and the TMJ branch originating directly from the mandibular nerve medially, and that there are variations in these innervation pathways. Additionally, we emphasized how these nerves might be affected in certain clinical conditions based on their anatomical relationships and pathophysiological mechanisms. To our knowledge, this is the first study showing the existence of a branch of the mandibular nerve directly innervating the TMJ. CONCLUSION: In light of our findings, elucidating TMJ pain based on the anatomical characteristics of the region will allow precise treatment algorithms and better clinical outcomes in these patients. Based on this study, new clinical studies and interventions can be designed to reduce healthcare costs and alleviate the burden of temporomandibular disorders.

Defining a Preauricular Safe Zone: A Cadaveric Study of the Frontotemporal Branch of the Facial Nerve.

BACKGROUND: In the preauricular region, the frontotemporal branch of the facial nerve is vulnerable to injury, which can result in facial palsy and poor cosmesis after surgical interventions. OBJECTIVES: The purpose of this study was to describe variations in the branching patterns of the frontotemporal branch of the facial nerve and the relation between this branch and the surrounding anatomic landmarks. Based on our findings, we propose a Danger Zone and Safe Zones for preauricular interventions to avoid frontal branch injury. METHODS: Twenty cadaveric half-heads, 10 freshly frozen and 10 embalmed, were dissected. The anatomy of the auriculotemporal nerve, facial nerve, and variations of its branching pattern in the preauricular region were investigated. RESULTS: The mean [standard deviation] number of frontotemporal branches crossing the zygomatic arch was 2.05 [0.6]. Beginning from the X point at the apex of the intertragal notch, frontal branches ran over the zygomatic arch at a distance extending from 10 to 31 mm anterior to the tragus, which can be defined as the Danger Zone for frontal branches. Safe Zones A and B are triangular regions located behind and in front of the Danger Zone, respectively. CONCLUSIONS: Mapping of these Safety and Danger Zones is a reliable and simple approach in preauricular interventions to avoid frontal branch injury because the facial nerve typically has multiple frontal branches. This approach provides practical information for surgeons rather than estimating the trajectory of a single frontal branch from Pitanuy's line.