Anatomical study of trigeminal-facial nerve communications: Application to facial transplant surgery

Understanding the distribution of nerves in the superficial layer of the face and the communication (nerve anastomosis) between them is essential for preventing paralysis during tumor removal and for planning during nerve grafting. However, communication between the peripheral branches of the trigeminal and facial nerves has not been fully elucidated owing to the delicacy of their structures and the ambiguity of definitions in previous reports. In this study, we used whole-mount nerve staining to differentiate between the two types of interaction between the trigeminal and facial nerves. "Nerve communication" is defined as an exchange of fibers between the two nerves, while "nerve crossing" indicates that only the epineuria are in close contact, with no exchange of fibers. The skin and soft tissues of six human faces were excised, and the nerves were stained using Sihler's method. The peripheral branches of the ophthalmic nerve showed no communication with the facial nerve. In half of the cases (3/6), the infraorbital nerve, representing the peripheral branch of the maxillary nerve, communicated with the facial nerve. Peripheral branches of the mandibular nerve communicated with the facial nerve via the auriculotemporal (6/6), buccal (6/6), and mental (3/6) nerves. Our findings demonstrate moderate communication between the peripheral branches of the trigeminal and facial nerves in the maxillary nerve region but more concentrated communication in the mandibular nerve region.