Goals/Purpose:
Inadvertent violation of the platysma can lead to marginal mandibular nerve (MMN) injury. We attempted to clarify the distal facial anatomy and relationship of the mandibular osseocutaneous ligament (MOCL), platysma mandibular ligament (PML), MMN, and depressor anguli oris muscle (DAO) as guideline for facelift surgery dissections.
Methods/Technique:
The MOCL, PML, MMN branches, DAO, and facial vessels were identified in 22 cadaver hemifacial dissections. The gonial angle and lower mandibular border were used to define the locations of the facial ligaments to each other and to the MMN branch in the vertical and horizontal planes respectively. 95% confidence regions were created.
Results/Complications:
The mean length, width, and depth of the MOCL were 13.1, 3.6, and 5.4 mm, and 21.6, 3.5, and 5.6 mm for the PML, respectively. Within a 95% confidence interval the MOCL and PML (origins) were located 56.2 ± 3.1 and 48.5 ± 4.4 mm from the gonial angle (horizontal distance), and 9.1 ± 0.9 and 1.5 ± 0.8 mm from the lower mandibular border (vertical distance), respectively. The MOCL and PML (ends) were located 67.8 ± 3.3 and 67.8 ± 5.4 mm from the gonial angle, and 9.3 ± 1.6 and 1.3 ± 0.8 mm from the lower mandibular border, respectively. The MOCL was located on average 8.4 mm superior to the PML.
The MMN had an average of 2.1 branches, with variable branch points to the facial vessels and MOCL. The course of the terminal MMN branch was always superior to the MOCL, with a distance of 9.7 ± 1.2 mm and deep to the DAO.
Conclusion:
Inadvertent penetration of the platysma superior to the MOCL is more likely to lead to MMN injury than inferior violation. An understanding of the 3 dimensional anatomy of the lower face is the best strategy of minimizing facial nerve injury.
