The facial nerve is also known as the seventh cranial nerve (CN7). This nerve performs two major functions. It conveys some sensory information from the tongue and the interior of the mouth. Specifically, CN7 serves about two-thirds of the tongue's anterior. The nerve extends from the brain stem, at the pons and the medulla. Also, this nerve innervates facial muscles, controlling how to contract and produce facial expressions. During its course, CN7 splits into several branches. The greater petrosal nerve serves the lacrimal gland and the nasal cavity, as well sphenoid, frontal, maxillary, and ethmoid sinuses. The nerve to the tapedius provides motor signals to the stapedius muscle, which is situated in the inner ear. Plus, the chroda tympani serve the submandibular and sublingual glands. The chorda tympani also convey taste sensations from the anterior two-thirds of the tongue. Most problems involving the facial nerve include paralysis, commonly with Bell's palsy. This condition, as well as other forms of paralysis, is often triggered by a viral infection or complications of Lyme disease.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Facial nerve