Lateral Perspective of the Mandibular Branch of the Facial Nerve

Description

Arising from the parotid plexus, the marginal mandibular branch of the facial nerve (ramus marginalis mandibulae nervi facialis) courses anteriorly from the parotid gland across the lateral face toward the lower lip. From this lateral perspective, its yellow neural filaments track along and just inferior to the inferior border of the mandible, superficial to the masseter at the mandibular angle and then running toward the region of the depressor anguli oris and depressor labii inferioris. Nearby, the parotid gland sits posterolateral to the mandibular ramus, while the facial artery and facial vein sweep across the mandible near the anterior border of the masseter. Small lymph nodes and channels cluster along the submandibular region. Surgical anatomy of this branch is unforgiving. During parotidectomy, submandibular gland surgery, or a facelift (rhytidectomy) with SMAS dissection, the marginal mandibular branch is at risk where it crosses the mandible and traverses the upper neck, and an injury produces asymmetric lower lip depression with drooling and an uneven smile. Relationship to the facial vessels matters because the nerve often runs superficial to the facial vein and may dip below the mandibular margin, a variant that increases vulnerability with low incisions. Plastic surgery atlases, head and neck anatomy courses, and operative consent materials benefit from a clear lateral map of the mandibular branch against the masseter, mandible, and parotid tissues. Add it to teaching sets on cranial nerve VII, facial expression musculature, and regional lymphatics for dental, ENT, and maxillofacial trainees. Anatomical accuracy verified by SciePro's Medical Advisory Board.