Trigeminal Nerve(redirected from fifth cranial nerve)
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trigeminal nerve[trī′jem·ə·nəl ′nərv]
the fifth pair of cranial nerves. It contains sensory, motor, and autonomic fibers.
The nuclei of the trigeminal nerve are located in the brain stem. The fibers of the trigeminal nerve that constitute the larger, or posterior, root pass from the brain stem to the apex of the temporal bone, where the trigeminal ganglion is located. Three branches depart from the trigeminal ganglion, as follows. The ophthalmic (sensory) nerve leaves the skull through the superior orbital fissure and innervates the upper eyelids, the conjunctiva, the skin of the forehead, and the anterior part of the scalp. The superior maxillary (sensory) nerve leaves the skull through the foramen rotundum, enters the pterygopalatine fossa, and innervates the skin of the lower lid, the cheek and nose, the mucosa of the nasal cavity, and the upper jaw. The inferior maxillary nerve (which is joined to the smaller, or anterior, root of the trigeminal nerve, containing the motor fibers) leaves the skull through the foramen ovale and innervates the skin of the lower part of the face, the mucosa of the cheeks and tongue, the lower jaw, and the muscles of mastication.
The trigeminal nerve takes part in many reflexes, including the corneal and mandibular (jaw) reflex. The most common disease of the trigeminal nerve is neuralgia, manifested by attacks of acute pain in the zone of innervation. Other diseases of the trigeminal nerve, including neuritis and infection with the virus of herpes zoster, are accompanied by sensory and motor disturbances in the zone of innervation.
V. A. KARLOV