Sensory Auricular Branch of the Facial Nerve

Goal To better describe the anatomy of the sensory auricular branch of the facial nerve. Background Clinical experience and the medical literature suggest that the facial nerve supplies sensory fibers to the external auditory canal and pinna. The anatomic distribution of these fibers remains poorly defined. Methods Ten cadaveric temporal bone dissections with photographic documentation, two clinical cases, and histologic examination of a candidate nerve fiber were collected. Results The anatomic distribution and histologic confirmation of a facial nerve branch coursing through the posterior wall of the external auditory canal is described. Mean (±SD) measurements along the mastoid segment of the facial nerve from the short process of the incus and chorda tympani nerve origin to the auricular branch origin were 11.6 ± 1.4 mm (range 9–13 mm) and 3.9 ± 3.0 mm (range 0–8 mm), respectively. Sacrifice of this nerve in a patient resulted in posterior external auditory canal and inferior conchal bowl hypesthesia. Conclusion The anatomy of a facial nerve branch coursing through the external auditory canal is presented. The anatomic and functional findings of this study suggest that this nerve represents an auricular sensory branch. Understanding these anatomic details may help in identifying the main trunk of the facial nerve in surgery, preventing postoperative external auditory canal hypesthesia, as well as understanding the significance of Ramsay-Hunt Syndrome and Hitselberger's Sign.