Introductory Chapter: Facial Nerve - An Overview

The facial nerve (seventh cranial nerve—CNVII) is the nerve of facial expression. It innervates all superficial muscles of the face and scalp, the contraction of which is responsible for all our numerous facial expressions like anger, pain, fear, smile, etc. Facial disfigurement resulting from facial nerve disorders can affect the physical, psychological, and emotional integrity of an individual. This might result in social, occupational, and educational handicap. The facial nerve is one of the most common cranial nerves implicated by disorders. It is a mixed nerve, which carries motor, sensory, and parasympathetic fibers. The motor fiber-innervated muscles developed from second branchial arch, the sensory fibers transmit the special sense of taste, and the parasympathetic fibers supply the submandibular, sublingual, and lacrimal glands [1]. Embryologically speaking, it is formed very early within the acousticofacial complex from the second branchial arch [2]. Facial nerve consists of the juxtaposition of somatic and branchial elements of the cranial nerve nuclei, in particular, accounting for trigeminal and facial nerve anastomosis [3]. A wide variety of disorders can involve the facial nerve including congenital, traumatic, infectious, inflammatory, and neoplastic disorders.