facial nerve

The seventh cranial nerve (VII). The facial nerve arises from the pons and medulla oblongata (parts of the brainstem) and leaves the posterior fossa of the skull by entering the interior auditory meatus on the inner aspect of the temporal bone with the eighth cranial nerve (the auditory nerve). After a winding course, it emerges in front of the mastoid process, and enters the parotid gland, in which it divides, sending branches to the face, neck, salivary glands, and outer ear.

The facial nerve performs both motor and sensory functions. It controls the muscles of the neck and of facial expression (including muscles in the forehead); it also stimulates secretion by the submandibular and sublingual salivary glands. In addition, the facial nerve conveys taste sensations from the front two thirds of the tongue and carries sensations from the outer ear. A small branch to the middle ear regulates the tension on the auditory ossicles.

Paralysis of the facial nerve, causing weakness and loss of function of the muscles it serves, results in facial paralysis. It occurs in Bell's palsy. The commonest cause is infection with the herpes simplex virus.

Related category

• ANATOMY AND PHYSIOLOGY

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