Revisiting the Topographic Anatomy of the Marginal Mandibular Branch of Facial Nerve Relating to the Surgical Approach.

Abstract

The marginal mandibular branch (Mbr) of the facial nerve is vulnerable to damage during rhytidoplasty, surgical reduction of the mandibular angle, parotidectomy, and excision of the submandibular gland. The authors sought to map the Mbr and determine the relationship between the number of Mbr offshoots and the course of the Mbr. The Mbr was examined in 29 hemifaces from 12 embalmed and 4 fresh cadavers (10 males, 6 females; mean age, 73.7 years). The Mbr was located ≤5 mm from the gonion (Go) in 24 of 29 hemifaces (82.8%) and ≤10 mm from the intersection of the facial artery and mandible (ie, FM) in 26 hemifaces (89.7%). In 16 hemifaces (55.2%), offshoots arose from the Mbr inferior to the mandible. The Mbr ran below the Go in 14 hemifaces (48.3%) and ran below FM in 13 hemifaces (44.8%). Except for minute offshoots deep to the platysma, the Mbr was not found to pass >2 cm below the mandible. The mean (± standard deviation) quantity of Mbr offshoots was 1.5 (± 0.6). A greater number of offshoots was associated with a higher likelihood of an inferiorly located nerve. The Mbr proceeded under the lower border of the mandible in 13 hemifaces (44.8%) and reached the mandible at a mean distance of 33.1±5.2 mm anterior to the Go. To avoid damaging the Mbr, surgical maneuvers should be positioned 4.5 cm anterior to the Go and 2 cm below the mandible.