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The fifth cranial nerve, also known as the trigeminal nerve, is part of the central nervous system. This nerve is considered to be a sensory nerve, primarily responsible for the sensations felt in the facial area. In spite of being classified as a sensory nerve, it is responsible for a limited amount of motor function as well, particularly related to the acts of chewing and swallowing.
Cranial nerves have their origin in the brain, and this nerve begins in the brain stem. The brain stem is located near the bottom of the skull at the back of the head and is responsible for such functions as consciousness, attention, and arousal.
The largest of the cranial nerves, the fifth cranial nerve has three branches, each responsible for facial sensation. One of the branches is also responsible for limited motor function. The three branches of this nerve are referred to as the maxillary, ophthalmic, and mandibular branches, or nerves.
The maxillary branch provides sensation to the top portion of the face, as well as to the nose and cheeks. It is a purely sensory nerve, not contributing to any of the motor function involving the face.
The ophthalmic branch, like the maxillary branch, is purely a sensory nerve. It provides the nerve supply to the eyes and the surrounding structures, including the skin of the forehead and nose.
The mandibular branch is the largest and also provides some motor function. This is the nerve branch responsible for sensation in the lower portion of the face. The acts of biting, chewing, and swallowing are influenced by this nerve as well.
Trigeminal neuralgia is a medical condition that affects the fifth cranial nerve. The exact cause of this condition is unknown, although there is a higher prevalence of it in patients with certain other medical conditions, such as multiple sclerosis. This condition causes extreme facial pain that can last from a few minutes to several hours at a time. Treatment is generally administered by a dentist and often includes prescription medications, with dosages and medicine combinations often having to be changed from time to time. In some cases, surgery is necessary to relieve pressure on the nerve.