Marginal mandibular branch of the facial nerve: An anatomical study

IntroductionKnowledge of the course and anatomical relations of the marginal mandibular branch of the facial nerve (MMBFN) in the head and neck is important to avoid its injury during surgery.AimThe aim of this work was to study the course and relations of the (MMBFN) to the lower border of the mandible and parotid gland.Material and methodsThe material of this work included thirty halves of formalin preserved head and neck specimens obtained from the Dissecting Room of Anatomy Department, Faculty of Medicine, Alexandria University.ResultsResults showed that the (MMBFN) arises as a single branch, two branches, and three branches in 36.7%, 43.3% and 20% of specimens, respectively. In 83.3% of cases, one of the main or secondary branches of the marginal mandibular nerve crosses superficial (lateral) to the facial vessels. There are communications either between the main or the secondary branches of the marginal mandibular nerve itself in 53.6% of specimens and with the buccal branch of the facial nerve in 40%, also with the anterior branch of the great auricular nerve in 3.3%, and with the transverse cervical nerve in 3.3% of specimens. The relationship of the nerve to the lower border of the mandible at a point midway between the angle of the mandible and symphysis menti is variable; it is either totally above it in most of the specimens 80%, or below it in 10% or at it in the remaining 10% of the specimens. The branches that lie above the lower border of the mandible are always deep into the superficial layer of the parotid fascia, while those branches that lie below the lower border of the mandible are intrafascially. The termination of the nerve is deep into the muscles of the ipsilateral lower lip in all specimens.