Finding the masseteric nerve: an illustrated surgical guide for facial reanimation

The masseteric nerve (MN) is a reliable donor nerve in facial reanimation. Masseteric-to-facial nerve transfer offers advantages including close proximity to facial nerve branches, strong axonal input, and minimal donor-site morbidity. However, safe and efficient identification of the MN can be challenging, particularly for surgeons less familiar with this region. A structured, reproducible approach is therefore essential.

14 fresh-frozen hemifaces were dissected to identify the MN and define its topographic relationships. Distances were measured relative to the apex of the tragus, the caudal edge of the zygomatic arch, and the superficial musculoaponeurotic system (SMAS). Based on these findings, a step-by-step surgical guide was developed, completed by schematic illustrations and an intraoperative video tutorial.

The MN was consistently located 3.89 ± 0.27 cm anterior to the apex of the tragus, 1.01 ± 0.18 cm inferior to the zygomatic arch, and 1.11 ± 0.21 cm deep to the SMAS. It was found in close proximity to the frontal branch of the facial nerve, typically directly beneath it or slightly anterior or posterior to it. Despite minor anatomical variations, a reproducible dissection pathway was defined. The resulting illustrated guide and video tutorial highlight key anatomical landmarks and safe dissection zones.

This cadaveric study and surgical tutorial provide a practical, reliable guide to identify the MN. The structured, step-by-step approach is designed to support both trainees and experienced surgeons, thereby improving safety, precision, and surgical efficiency in facial reanimation.