Transposition of the Hemimasseteric Muscle for Dynamic Rehabilitation of Facial Paralysis

Background: The masseter muscle is one of the muscles involved in mastication. Transposition of this muscle has been used for dynamic reanimation of facial palsy since the early years of the 20th century. We present an anatomic study of the masseter muscle and its neurovascular bundle to determine the possibility of using hemimasseteric transposition of the muscle for the rehabilitation of facial paralysis. Methods: Six white fresh cadavers were used to study the masseter nerve and the vascular supply to the masseteric muscle. Dissection was performed in each hemiface of each specimen. All the masseter nerve bundles were dissected to study their distribution. Anatomic Study: A constant anatomy was examined in all the specimens dissected. Dissection was performed inside the muscle body to expose the whole masseter nerve and its branches. A treelike design of the nerve branches was observed. Each nerve branch was accompanied by its corresponding vascular pedicle, which guaranteed the vascular supply to the muscle divisions. Conclusions: The knowledge of the anatomy of the masseter nerve and its vascular supply is the key to preventing nerve damage when the muscle is split for facial reanimation. The possibility of selecting the bundle included in the transposed section of the muscle could be used for dynamic reanimation of the paralyzed face.