What is the hypoglossal nerve?
The hypoglossal nerve is one of 12 cranial nerves. It’s also known as the 12th cranial nerve, cranial nerve 12 or CNXII.
This 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.
What type of nerve is the 12th cranial nerve?
It’s a motor nerve that carries signals to and from the brain to control muscle movement.
What is the function of cranial nerve 12?
The hypoglossal nerve controls muscles that move the tongue, enabling you to:
- Make noises with your mouth, like clicking sounds.
- Move substances around in your mouth.
Which muscles do the hypoglossal nerve control?
Cranial nerve 12 controls the:
- Genioglossus muscles, which push the tongue forward.
- Hyoglossus muscles that pull the tongue back and flatten it.
- Intrinsic muscles that change the tongue’s shape, including curving and narrowing.
- Styloglossus muscles, which move the tongue up and down.
What is the anatomy of the 12th cranial nerve?
The hypoglossal nerve starts in the base of the brain near the top of the spinal cord (brain stem).
Before reaching the tongue, it:
- Travels down the spinal cord to the cervical plexus. This complex nerve network enables sensation and movement in the neck and trunk.
- Runs down the 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.
Conditions and Disorders
What conditions affect hypoglossal nerve function?
Conditions affecting this nerve include:
- Amyotrophic lateral sclerosis (ALS): In advanced cases, the hypoglossal nerve might not be able to communicate with the brain.
- Encephalitis: Inflammation can cause the brain stem to press on the hypoglossal nerve.
- Head and neck cancer: Treatments can disrupt nearby tissue, including the hypoglossal nerve.
- Sleep apnea: The 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 the airway.
- Stroke: A lack of blood flow can affect the brain’s ability to communicate with the hypoglossal nerve.
- Trauma: Serious accidents like a stabbing can sever the hypoglossal nerve.
How can I prevent issues with cranial nerve 12?
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 such as ALS.
- Living a healthy lifestyle to prevent stroke.
- Maintaining a healthy weight to avoid sleep apnea or prevent it from worsening.
- Quitting smoking if you use tobacco and limiting alcohol consumption. Both of these prevent head and neck cancer.
Frequently Asked Questions
When should I call a healthcare provider about problems with my hypoglossal nerve?
Call your 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.
A note from Cleveland Clinic
The hypoglossal nerve helps you move your tongue. It enables you to speak, swallow and push substances around in your mouth. Conditions affecting hypoglossal nerve function include stroke, cancer and ALS. You can protect cranial nerve 12 from some of these conditions by living a healthy lifestyle.
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