Marginal mandibular branch of the facial nerve – morphology and variability

Abstract

Introduction The marginal mandibular branch (MMB) of the facial nerve is at high risk of iatrogenic injures in submandibular gland excisions, lymph nodes dissection, mandible trauma repairs and other surgeries of the head and neck. Considering high variability of the MMB, the aim of the current study was to determine its anatomical variants and clinical relevance, with a focus on its course, branching patterns, and spatial relationships to adjacent morphological structures, for enhancement of the surgical management. Material and methods A systemic review of relevant articles from PubMed, Web of Science, Scopus, MEDLINE, Google Scholar and Semantic Scholar databases has been done. As keywords the marginal mandibular branch, facial nerve, facial nerve trunk, parotid plexus and branching pattern were used. Results The number of the MMB varied from 1 to 4 branches, preponderantly being reported 1-2 MMB. An obvious difference of the MMB number, branching patterns and topography, between the analyzed studies, was emphasized. Three variants of its topography towards mandibular margin were revealed: above the mandibular margin, at its level and below it. The positioning of the MMB related to the facial vessels was lateral, medial and intermediate one. The MMB formed connections mainly with the cervical branch of the facial nerve and with the buccal branches. Connections with the buccal and mental nerves have also been reported. Conclusions The number, course, branching pattern and topography of the marginal mandibular branch are variable depending on gender, laterality and nationality.