183 Int. J. Morphol., 27(1):183-186, 2009. Anatomy of the Facial Nerve and its Implication in the Surgical Procedures Anatomía del Nervio Facial y sus Implicancias en los Procedimientos Quirúrgicos * Antonio de Castro Rodrigues; * Jesus Carlos Andreo; ** Laura de Freitas Menezes; *** Tatiana Pimentel Chinellato & * Geraldo Marco Rosa Júnior RODRIGUES, D. C. A.; ANDREO, J. C.; MENEZES, D. F. L.; CHINELLATO, P. T. & ROSA-JÚNIOR, G. M. Anatomy of the facial nerve and its implication in the surgical procedures. Int. J. Morphol., 27(1):183-186, 2009. SUMMARY: Facial palsy, parotid diseases and others are a relatively common clinical condition with a variety of causes. Irrespective of its etiology, facial palsy always represents a very serious problem for the patient. Parotid gland diseases also are very common occurrence. In this particular case, the knowledge of surgical anatomy of the facial nerve and its correlations with the parotid gland is very important for an adequate preservation in the cases of surgery of benign and malignant diseases of the parotid gland. Although the surgical anatomy of the facial nerve has been well documented, the concept of surgical treatment for parotid tumors, facial palsy (neurorraphy techniques) and submandibular surgical approach are rarely challenged now. KEY WORDS: Facial nerve; Surgical anatomy; Facial palsy; Parotid gland. INTRODUCTION The facial nerve consists of the facial nerve proper and the intermedius nerve. The former originates from motoneurons in the facial nucleus situated ventrolaterally in the caudal portion of the pons. The motor axons first turn dorso-medially towards the abducens nucleus round the dor- sal side of this nucleus and then course ventrolaterally. Both the facial nerve proper and the intermedius nerve emerge from the CNS in the cerebellopontine angle at the caudal border of the pons, between the abducens nerve and the stato- acoustic nerve (Machado, 1998). As it exits through the stylomastoid foramen, the extracranial portion of the facial nerve may be located 5 cm below the skin. Here, it immediately gives off branches to the auricular muscles, the posterior belly of the digastric muscle and the stylohyoid muscle. It supplies sensory (vagal) fibers to parts of the external auditory canal and some areas to the auricle, including the lobulus (Ranson & Clark, 1959; Barr & Kiernan, 1983; May & Schaitkin, 2000). The nerve then courses ventrally and at the posterior edge of the parotid gland, it splits into upper and lower divisions. Within the parotid gland, there is further branching with many indivi- dual variations (Davis et al., 1956). As a rule, the upper division of the facial nerve gives off temporal, zygomatic and buccal branches, whereas the lower division emits mar- ginal mandibular and cervical branches. There are 23 facial muscles, most of which are paired. In facial expressions, 17 muscles are activated (Freilinger et al., 1990). The knowledge of surgical anatomy of the facial nerve and its correlations with the parotid gland and facial muscles are very important for an adequate preservation in the cases of surgery in this area. The iatrogenic injury in this facial region is very common. The choice of the surgical approach is very relevant in the parotid surgery because of the extre- me anatomic variability of the parotideal area and the functional importance of the branches of facial nerve. MATERIAL AND METHOD Fifteen cadavers were dissected. They came from Laboratory of Anatomy (University of São Paulo - FOB/ * Department of Biological Sciences, FOB / USP, Bauru, São Paulo, Brazil. ** Laboratory of Anatomy Intern FOB/USP/Bauru, São Paulo, Brazil. *** University of Sacrated Heart, Student USC/Bauru, São Paulo, Brazil.