Cranial Nerves: Function, Anatomy And Location - Cleveland Clinic

Home/Health Library/Body Systems & Organs/Cranial NervesAdvertisementAdvertisementCranial Nerves

Your cranial nerves are a set of 12 paired nerves that stem from your brain. They have a wide variety of functions, including helping you see, taste, smell, hear and feel sensations. They also help you make facial expressions, blink your eyes and move your tongue.

Advertisement

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Care at Cleveland ClinicNeurology Care for AdultsNeurology Care for ChildrenMake an AppointmentContentsArrow DownOverviewFunctionAnatomyConditions and DisordersCareAdditional Common QuestionsContentsArrow DownOverviewFunctionAnatomyConditions and DisordersCareAdditional Common Questions

Overview

What are the cranial nerves?

Your cranial nerves are a set of 12 nerves that send electrical signals between your brain and different parts of your head, face, neck and torso. These signals help you see, smell, taste, hear and move your facial muscles. Your cranial nerves begin toward the back of your brain. They’re a key part of your nervous system.

Advertisement

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

You might first think of your eyes, nose, ears and mouth when it comes to using your senses. But these body parts don’t work properly without healthy cranial nerves. You can also thank your cranial nerves for allowing you to make facial expressions and communicate.

How many cranial nerves are there?

You have 12 cranial nerve pairs. Each nerve pair splits to serve the two sides of your brain and body. For example, you have one pair of olfactory nerves. One olfactory nerve is on the left side of your brain, and one is on the right side of your brain.

Care at Cleveland ClinicNeurology Care for AdultsNeurology Care for ChildrenMake an Appointment

Function

What is the function of the cranial nerves?

Your cranial nerves play a role in relaying sensory and/or movement (motor) information.

Sensory nerves can help you:

• Feel touch and sense pain and temperature.
• Hear.
• See.
• Smell.
• Taste.

Motor nerves play a role in controlling specific muscles. Some cranial nerves have both sensory and motor functions.

Your 12 cranial nerves each have a specific function. Healthcare providers categorize the cranial nerves based on number and function:

• Olfactory nerve (CN I): Providing the sense of smell.
• Optic nerve (CN II): Providing vision.
• Oculomotor nerve (CN III): Opening and moving your eyes and adjusting pupil width.
• Trochlear nerve (CN IV): Looking down and moving your eyes toward your nose or away from it.
• Trigeminal nerve (CN V): Providing sensations in your eyes, most of your face and inside your mouth. It also allows you to chew food.
• Abducens nerve (CN VI): Moving your eyes from left to right.
• Facial nerve (CN VII): Controlling several facial muscles to make facial expressions and providing the sense of taste in part of your tongue.
• Vestibulocochlear nerve (CN VIII): Providing the sense of hearing and balance.
• Glossopharyngeal nerve (CN IX): Providing taste sensations to part of your tongue and controlling muscles for swallowing. It also has parasympathetic nerve fibers that play a role in blood pressure regulation and saliva (spit) production. 
• Vagus nerve (CN X): Regulating several automatic bodily processes, including your digestion, blood pressure, heart rate, breathing, mood, saliva production and more. It’s the main nerve of your parasympathetic nervous system.
• Accessory nerve or spinal accessory nerve (CN XI): Controlling shoulder and neck movement.
• Hypoglossal nerve (CN XII): Controlling tongue movement, which plays a role in speaking, eating and swallowing.

Advertisement

Anatomy

Where are the cranial nerves located?

Two of your cranial nerve pairs — your olfactory and optic nerves — begin in your cerebrum and branch out to their target tissues. The cerebrum is the largest portion of your brain that sits above your brainstem.

The other 10 pairs of cranial nerves start in your brainstem and then branch out. Your brainstem connects your brain and spinal cord.

What is the longest cranial nerve?

The longest cranial nerve is your vagus nerve. It runs from your brain to your large intestine, innervating several tissues along the way.

Conditions and Disorders

What conditions affect your cranial nerves?

When a cranial nerve experiences damage, it doesn’t function as it should. This may cause specific movement or sensory issues, depending on its underlying function. Several conditions and situations can affect the functioning of your cranial nerves, like:

• Head trauma or traumatic brain injury.
• Nervous system or brain conditions, such as neuropathy and amyotrophic lateral sclerosis (ALS).
• Pressure from nearby blood vessels, tumors or swelling.
• Circulatory issues, like microvascular disease and stroke.
• Inflammation from certain infections, such as the herpes zoster virus (the virus that causes shingles).
• Autoimmune conditions, like scleroderma and Sjögren’s syndrome.
• Accidental damage from brain, facial or dental surgery.

Cranial nerve palsies

When there’s an issue with a specific cranial nerve that has a motor (movement) function, healthcare providers often call it a palsy. “Palsy” means “paralysis.” A palsy results in muscle weakness and movement issues.

Examples of cranial nerve palsies include:

• Third nerve palsy (oculomotor palsy): This condition typically causes one of your eyes to stay positioned as though you’re looking down and out to the side.
• Fourth nerve palsy (trochlear nerve palsy): This condition typically causes double vision vertically and difficulty looking downward.
• Sixth nerve palsy (abducens nerve palsy): This condition typically causes eye misalignment (strabismus) and double vision.
• Bell’s palsy: This condition affects your facial nerve and is a type of facial nerve palsy. It usually causes temporary drooping on one side of your face.

Other cranial nerve conditions

Another specific type of cranial nerve condition is trigeminal neuralgia. This condition causes episodes of intense facial pain that can disrupt your everyday activities. It typically happens when a blood vessel puts pressure on your trigeminal nerve.

Some cranial nerves, like your optic nerve and vagus nerve, can have several types of dysfunction. For example, conditions that affect your optic nerve include glaucoma and optic neuritis. Conditions that can arise from vagus nerve dysfunction include gastroparesis and vasovagal syncope (fainting).

Advertisement

Care

How can I keep my cranial nerves healthy?

Some cranial nerve conditions are unpreventable. But you can help keep your brain, cranial nerves and entire nervous system healthier with these steps:

• Reach and maintain a weight that’s healthy for you.
• Eat nutrient-dense foods like fruits, vegetables and whole grains.
• Get regular physical activity.
• Keep your blood pressure within a healthy range.
• Manage any conditions that increase your risk of nerve damage, like diabetes.
• Drink alcohol only in moderation.
• Quit smoking.

When should I see my healthcare provider?

The symptoms of cranial nerve injuries or conditions vary depending on which nerve is affected. Contact your healthcare provider if you experience:

• Drooping on one side of your face.
• Facial pain or numbness.
• Muscle weakness or paralysis.
• Tingling anywhere in your body.
• Vision issues.
• Taste or smelling issues.
• Slurred speech (dysarthria).
• Difficulty chewing or swallowing (dysphagia).

Additional Common Questions

Is there an easy way to remember the cranial nerves with a mnemonic?

Cranial nerve mnemonics are memory devices to help you remember the names of the nerves in order of one through 12. They can also help you remember whether the nerves are sensory, motor or both.

Cranial nerve mnemonics to remember the names of the nerves in order include:

• On old Olympus’s towering top, a Finn and German viewed some hops.
• Ooh, ooh, ooh to touch and feel very good velvet. Such heaven!

Advertisement

It’s important to note that in these mnemonics, “some” and “such” refer to another name for the accessory nerve: spinal accessory nerve.

To remember cranial nerve functions, the words in the mnemonic start with:

• S for sensory.
• M for motor.
• B for both.

The word order mirrors the numerical order of nerves one through 12:

• Some say marry money, but my brother says big brains matter more.
• Some say my mother bought my brother some bad beer, my, my.

A note from Cleveland Clinic

Without your cranial nerves, it’d be impossible to experience the world around you — from seeing and hearing to smelling and tasting. They’re also essential for moving your eyes, tongue, mouth and various parts of your face. It’s easy to take these nerves for granted until something goes wrong. If you develop sudden issues with your senses or have symptoms related to functions involving your face, an issue with a cranial nerve may be the cause. It’s important to see a healthcare provider if this happens — they can get to the bottom of the issue.

Advertisement

Care at Cleveland Clinic

If you have a neurological condition, you want expert advice. At Cleveland Clinic, we’ll work to create a treatment plan that’s right for you.

Neurology Care for AdultsNeurology Care for ChildrenMake an AppointmentMedically Reviewed

Last reviewed on 08/15/2024.

Learn more about the Health Library and our editorial process.

References

AdvertisementAdvertisementAdAppointments 866.588.2264Appointments & LocationsRequest an Appointment