Bony Anatomic Landmarks to Avoid Injury to the Marginal Mandibular Nerve

Background: Marginal mandibular nerve injuries are more likely to be symptomatic than other facial nerve injuries following facelift procedures. The marginal mandibular nerve courses over the facial artery in the region of the mandible. The nerve is most susceptible to injury in this location because it lies superficial to the anterior facial artery. Objectives: The authors describe the location of the marginal mandibular nerve based on superficial anatomic landmarks as it crosses the facial artery above the mandibular border, in order to help surgeons avoid injury to this nerve during facelift procedures. Methods: Eighteen cadaveric facial halves were dissected with the aid of loupe magnification. The distance from the facial artery to the palpable masseteric tuberosity at the angle of the mandible was measured. The distance from the masseteric tuberosity to the mental midline was also measured to determine a ratio of the facial nerve from the masseteric tuberosity to the mental midline. Results: The facial artery was found to be an average of 3.05 +/- 0.13 cm anterior to the masseteric tuberosity along the mandible. The marginal mandibular nerve crossed the facial artery along the mandibular border approximately 3 cm anterior to the masseteric tuberosity. The distance from the masseteric tuberosity to the mental midline averaged 11.3 +/- 0.54 cm. Therefore, the marginal mandibular nerve courses superficial to the facial artery at approximately one-fourth of the distance from the masseteric tuberosity to the mental midline. Conclusions: Knowledge of the masseteric tuberosity and mental midline landmarks of the facial artery can provide a reliable and safe approach to surgery of the lower face.