Hypoglossal Nerve

What is the hypoglossal nerve?

Your hypoglossal nerve is one of your 12 paired cranial nerves. Your hypoglossal nerve starts at the base of your brain. It travels down your neck and branches out, ending at the base and underside of your tongue. Its name comes from the Greek words “hypo,” which means under, and “glossal,” which means tongue.

Your hypoglossal nerve is a motor nerve that carries signals to and from your brain to control muscle movement.

Other names for your hypoglossal nerve include:

• Cranial nerve 12.
• 12th cranial nerve.
• CNXII.

What is the function of the hypoglossal nerve?

Your hypoglossal nerve controls muscles that move your tongue, allowing you to:

• Make noises with your mouth, like clicking sounds.
• Move substances around in your mouth.
• Speak.
• Swallow.

Which muscles do the hypoglossal nerve control?

Your hypoglossal nerve controls your:

• Genioglossus muscles: These muscles push your tongue forward.
• Hyoglossus muscles: These muscles pull your tongue back and flatten it.
• Intrinsic muscles: These muscles change your tongue’s shape, including curving and narrowing.
• Styloglossus muscles: These muscles move your tongue up and down.

What is the hypoglossal nerve anatomy?

Your hypoglossal nerve starts in the base of your brain near the top of your spinal cord (brainstem).

Before reaching your tongue, it:

• Travels down your spinal cord to your cervical plexus. This complex nerve network lets you feel sensation and movement in your neck and trunk.
• Runs down your neck past important blood vessels (carotid artery and jugular vein).
• Extends past the back of your throat until it reaches the floor of your mouth.
• Branches off to connect with muscles that control different types of tongue movement.

What conditions affect hypoglossal nerve function?

Any of the following conditions may affect hypoglossal nerve function:

• Amyotrophic lateral sclerosis (ALS): Also called Lou Gehrig’s disease, ALS is a neuromuscular disorder that leads to muscle weakness. In advanced cases, your hypoglossal nerve might not be able to communicate with your brain.
• Encephalitis: Encephalitis can occur when an infection or an autoimmune reaction causes swelling (inflammation) of your brain. The inflammation can cause your brainstem to press on your hypoglossal nerve.
• Head and neck cancer: This refers to types of cancers that can affect your mouth, throat or other parts of your head and neck. Cancer treatments can disrupt nearby tissue, including your hypoglossal nerve.
• Sleep apnea: This is a sleep disorder that causes you to stop breathing while you’re asleep. Your hypoglossal nerve controls muscles in the back of your throat. If they relax too much during sleep, your tongue can slide out of place, blocking your airway.
• Stroke: A stroke is a condition that occurs when part of your brain doesn’t have enough blood flow. It most commonly happens because of bleeding in your brain or a blocked artery. A lack of blood flow can affect your brain’s ability to communicate with your hypoglossal nerve.
• Trauma: Trauma can occur in various forms, from car accidents to falls to violence. Serious accidents can sever your hypoglossal nerve.

Hypoglossal nerve damage symptoms

If you have hypoglossal nerve damage, your tongue weakens on the side that’s affected. It will eventually waste away (atrophy), leading to paralysis of your tongue. Because of this, you may have trouble swallowing, chewing and/or speaking.

Damage due to ALS can lead to subtle, tiny twitching movements (fasciculations) on the surface of your tongue.

If you have sudden pain along with any of these symptoms, you may have a dissected internal carotid artery.

How do you test for hypoglossal nerve function?

To test for hypoglossal nerve stimulation, your healthcare provider may ask you to protrude your tongue. Hypoglossal nerve damage usually only affects one side of your tongue. When you stick your tongue out, it may point to the damaged side. Your provider may also ask you to push your tongue against your cheek while feeling for pressure on the opposite side.

Your provider may also order certain tests, including:

• Magnetic resonance imaging (MRI): To check for evidence of a stroke or to see if you may have a tumor.
• Spinal tap (lumbar puncture): To look for signs of cancer or infection.

Common treatments for hypoglossal nerve damage

Treatment for hypoglossal nerve damage depends on the cause. Your healthcare provider will discuss this with you. For example, treatment for ALS may include medications and therapies to manage your symptoms and slow down the progression of the disease. Treatment for head and neck cancer may include surgery, radiation therapy and/or chemotherapy.

How can I prevent issues with my hypoglossal nerve?

Hypoglossal nerve issues can impact your ability to eat, speak or swallow. Some causes, like trauma and surgical complications, can be difficult to avoid. Seeing an experienced surgeon if you need a mouth or throat procedure may lower your risk.

Taking care of yourself can help you avoid disruption to hypoglossal nerve function. These efforts include:

• Following care instructions to slow the progression of chronic conditions, like ALS.
• Living a lifestyle that’s healthy for you to help prevent stroke.
• Maintaining a weight that’s healthy for you to help avoid sleep apnea or prevent it from worsening.
• Quitting smoking if you use tobacco and limiting alcohol consumption. Both of these can help prevent head and neck cancer.

When should I call a healthcare provider about problems with my hypoglossal nerve?

Call a healthcare provider if you experience issues on one or both sides of your tongue.

These may include:

• Difficulty speaking (aphasia) or swallowing (dysphagia).
• Lack of sensation.
• Muscle weakness.
• Pain or a burning sensation.
• Uncoordinated movement.