Optimizing facial reanimation: surgical landmarks for masseteric-to-facial nerve anastomosis

This study aimed primarily to establish a precise surgical anatomical guide for masseteric-to-facial nerve (MN-FN) anastomosis using reproducible anatomical landmarks. The secondary objective was to identify novel and reliable landmarks to facilitate the localization and dissection of the masseteric nerve (MN) during facial reanimation procedures.

A cadaveric study was performed on 22 hemifaces from 11 formalin-fixed cadavers. Standardized preauricular and temporal scalp incisions were used to expose the facial nerve (FN) and identify the MN. Distances from the tragus, zygomatic arch, and relevant bony landmarks to the MN were measured. Angles and depths were recorded bilaterally. Statistical analyses included Wilcoxon signed-rank test (p < 0.05).

For the primary objective, the MN was consistently located deep to the zygomatic arch, at a mean distance of 2.6 ± 0.4 cm anterior to the tragus and a mean depth of 1.2 ± 0.3 cm. The trajectory formed an average angle of 52.1 ± 6.2° with the zygomatic arch. These parameters were symmetrical bilaterally (p > 0.05), confirming their reproducibility. For the secondary objective, we identified a new "subzygomatic triangle" bordered by the zygomatic arch, posterior masseter border, and condylar neck. The MN was reliably found within this triangle in all specimens (12/12, 100%), with significantly reduced depth variability compared to standard techniques (p = 0.018).

This study defines reproducible anatomical references and introduces a novel landmark to enhance the safety and precision of MN-FN anastomosis in facial reanimation surgery.