The Subzygomatic Triangle: Rapid, Minimally Invasive Identification of the Masseteric Nerve for Facial Reanimation

Background: The masseteric nerve is a valuable donor nerve in the management of facial paralysis; however, its location is less familiar to surgeons because this motor nerve is not commonly exposed in other head and neck procedures. Current techniques for masseteric nerve identification rely on physical measurements from surface or bony landmarks that may be unpredictable across patient age, ethnicity, and size. The authors sought to identify a rapid and minimally invasive technique based on surgical anatomy independent of intraoperative physical measurements. Methods: A two-phase, fresh-frozen cadaver study was performed followed by a clinical application that included 11 consecutive patients undergoing facial reanimation procedures between May of 2012 and October of 2012. Results: Ten cadavers were dissected and 11 clinical applications are reported. In all dissections, the masseteric nerve was identified through the newly described "subzygomatic triangle." This triangle is formed by the zygomatic arch superiorly, the temporomandibular joint posteriorly, and the frontal branch of the facial nerve inferiorly and anteriorly. This finding was consistent across patient ages (8 to 49 years) and ethnicities. By using the short-scar, minimal dissection approach described in the study, average time to nerve identification was 10.2 minutes during the clinical application. Conclusions: The subzygomatic triangle is a consistent anatomic landmark for rapid, reliable, and minimally invasive identification of the masseteric nerve. Use of the subzygomatic triangle obviates the need for extensive dissection and surgeon reliance on soft-tissue measurements that may vary among patients of different size, sex, or ethnicity.