Anatomical Reassessment of the Mandibular Septum: Relationship with The Marginal Mandibular Nerve and Deep Structures of Lower Face.

BACKGROUND: The mandibular septum is not a well-defined anatomical structure and mostly known as a ligamentous formation which separates the jowl and submandibular fat compartments. OBJECTIVES: This study aimed to investigate the anatomical relationships between the mandibular septum(MS), the platysma-mandibular ligament (PML), together with the mandibular osteocutaneous ligament(MOCL), and the marginal mandibular nerve(MMN), with a focus on their potential relevance in facelift surgery. METHODS: The MS, PML, MOCL, and the MMN were identified in 14 cadavers(28 hemifaces). Layer-by-layer dissection techniques were carried out in the subcutaneous and subplatysmal planes using 3.5 magnifying surgical loupes. RESULTS: The MS and PML were observed to be continuous with one another, functioning as a supportive structure that limits inferior migration of jowl fat toward the neck. The MOCL was located superiorly 5.79±0.80 mm on the right side, whereas 5.43±0.94mm on the left side to the PML and MS(p>0.05). The MMN was identified inferiorly 8.43±1.91mm on the right side and 8.71±1.94 mm on the left side, to the MS at the gonial angle(p>0.05). At the junction point of the MS and PML, MMN crossed the mandible and continued in the preperiosteally to the mental foramen. CONCLUSIONS: The MMN courses inferior to the MS along the masseter muscle and becomes deeper at the anterior margin of the masseter, where it may be at increased risk of injury. These findings may improve surgical awareness during facelift procedures and aid in nerve preservation.