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Overview of the Cranial Nerves

By

Michael Rubin

, MDCM, New York Presbyterian Hospital-Cornell Medical Center

Last full review/revision Sep 2020| Content last modified Sep 2020
Click here for the Professional Version
Topic Resources

Twelve pairs of nerves—the cranial nerves—lead directly from the brain to various parts of the head, neck, and trunk. Some of the cranial nerves are involved in the special senses (such as seeing, hearing, and taste), and others control muscles in the face or regulate glands. The nerves are named and numbered (according to their location, from the front of the brain to the back).

Viewing the Cranial Nerves

Twelve pairs of cranial nerves emerge from the underside of the brain, pass through openings in the skull, and lead to parts of the head, neck, and trunk.

Viewing the Cranial Nerves

A cranial nerve disorder may result when the following are damaged or malfunction:

Some cranial nerve disorders interfere with eye movement. Eye movement is controlled by 3 pairs of muscles. These muscles move the eye up and down, right and left, and diagonally. The muscles are controlled by the following cranial nerves:

If one of these nerves or the area in the brain that controls these muscles is damaged, the muscles may become paralyzed to varying degrees (called a palsy), and people may not be able to move their eyes normally. How eye movement is affected depends on which nerve is affected. People with one of these palsies may have double vision when they look in certain directions.

Did You Know...

  • Some cranial nerve disorders interfere with eye movement, causing double vision.

Causes

Cranial nerve disorders have many causes, including the following:

Symptoms

Symptoms of cranial nerve disorders depend on which nerves are damaged and how they were damaged. Cranial nerve disorders can affect smell, taste, vision, sensation in the face, facial expression, hearing, balance, speech, swallowing, and muscles of the neck.

For example, vision may be affected in various ways:

If the 8th cranial nerve (auditory or vestibulocochlear nerve) is damaged or malfunctions, people may have problems hearing and/or have vertigo Dizziness and Vertigo Dizziness is an inexact term people often use to describe various related sensations, including Faintness (feeling about to pass out) Light-headedness Dysequilibrium (feeling off balance or... read more —a feeling that they, their environment, or both are spinning.

Cranial nerve disorders can also cause various kinds of facial or head pain.

Diagnosis

  • A doctor's evaluation

  • Tests of cranial nerve function

  • Usually magnetic resonance imaging

When doctors suspect a cranial nerve disorder, they ask the person detailed questions about the symptoms. They also test the function of the cranial nerves Cranial Nerves When a neurologic disorder is suspected, doctors usually evaluate all of the body systems during the physical examination, but they focus on the nervous system. Examination of the nervous system—the... read more by asking the person to do simple tasks, such as to follow a moving target with the eyes.

Imaging of the brain with magnetic resonance imaging (MRI) is often needed.

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Treatment

  • Treatment of the cause

Treatment of specific cranial nerve disorders depends on the cause.

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Others also read

Test your knowledge

Bell Palsy
Bell palsy is sudden weakness or paralysis of the muscles on one side of the face due to malfunction of the seventh cranial nerve. This nerve moves facial muscles, stimulates salivary and tear glands, detects tastes, and controls a muscle involved in hearing. Which of the following is often the first symptom of Bell palsy?
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