facial nerve

facial

 [fa´shal]

pertaining to or directed toward the face.

facial nerve the seventh cranial nerve; its motor fibers supply the muscles of facial expression, a complex group of cutaneous muscles that move the eyebrows, skin of the forehead, corners of the mouth, and other parts of the face concerned with frowning, smiling, or any of the many other expressions of emotion. The sensory fibers of the facial nerve provide a sense of taste in the anterior two thirds of the tongue, and also supply the submaxillary, sublingual, and lacrimal glands for secretion. Irritation of the facial nerve can produce a paralysis known as bell's palsy, which usually involves only one side of the face with a resulting distortion of facial expression such as inability to close the eye or part of the mouth on the affected side. See anatomic Table of Nerves in the Appendices.

facial nerve

n.

Either of the seventh pair of cranial nerves that control facial muscles and relay sensation from the taste buds of the front part of the tongue.

SUPERFICIAL BRANCHES OF FACIAL NERVE (7TH CRANIAL))

facial nerve

A mixed nerve consisting of efferent fibers supplying the facial muscles, the platysma muscle, the submandibular and sublingual glands; and of afferent fibers from taste buds of the anterior two thirds of the tongue and from the muscles.

Sensory

Taste fibers from the anterior two thirds of the tongue and the soft palate follow the chorda tympani to their neuronal cell bodies in the geniculate ganglion; the axons of these neurons follow the nervus intermedius (the sensory root of the facial nerve) into the pons where they synapse in the nucleus of the tractus solitarius (the gustatory nucleus).

Motor

Somatic motor axons from the motor nucleus of the facial nerve in the pons emerge as the motor root of the facial nerve and enter the bone of the skull through the internal auditory meatus. The motor axons follow the facial canal inside the temporal bone and exit the skull through the stylomastoid foramen. From there, the axons innervate all the muscles of facial expression. Preganglionic parasympathetic axons from the superior salivatory nucleus take the nervus intermedius to the region of the geniculate ganglion inside the facial canal. From there, some of the axons join the chorda tympani and later reach the submandibular ganglion by following the lingual nerve. Other preganglionic parasympathetic axons follow the major superficial petrosal nerve and the vidian nerve to reach the pterygopalatine ganglion.

Synonym: seventh cranial nerve See: illustration; cranial nerve

See also: nerve

facial nerve

One of the 7th of the 12 pairs of CRANIAL NERVES. Each facial nerve supplies the muscles of the face on its own side. Loss of function in a facial nerve causes partial or total paralysis of one side of the face. This is called BELL'S PALSY.

facial nerve

the 7th cranial nerve, a dorsal root that in mammals is mainly motor in function, supplying facial muscles, the salivary glands and the front-of-tongue taste buds.