Trigeminal Nerve

What is the trigeminal nerve?

Your trigeminal nerve, also known as cranial nerve 5 or CN V, is a large, three-part nerve in your head that sends signals from your brain to parts of your face, and vice versa. You have two trigeminal nerves — one on each side of your face. They’re one set of 12 cranial nerve pairs. Your trigeminal nerve is the largest of the cranial nerves.

Your trigeminal nerve is an important nerve that provides sensation to large parts of your face and allows you to chew food. But you may not think about your trigeminal nerve unless you or someone you know has trigeminal neuralgia — a condition that causes episodes of intense facial pain.

What is the function of the trigeminal nerve?

Your trigeminal nerve provides motor (movement) and sensory information for different aspects of your head and face. Motor nerve fibers tell your muscles when and how to move. Sensory nerve fibers send pain, touch and temperature sensations from your skin to your brain.

Your trigeminal nerve consists of three branches:

• Ophthalmic (V1) nerve.
• Maxillary (V2) nerve.
• Mandibular (V3) nerve.

Each of the three branches has different functions.

Ophthalmic nerve branch function

“Ophthalmic” means “eye.” The ophthalmic nerve branch provides sensory information for your face and skull in the opening between your eyelids of each eye (palpebral fissure). It also provides sensation for portions of your nasal cavity.

Sympathetic nerve fibers of this nerve branch play a role in dilating your pupils and supply sensation to the following parts of your eyes:

• Ciliary body.
• Iris.
• Lacrimal gland.
• Conjunctiva.
• Cornea.

Maxillary nerve branch function

“Maxillary” refers to your upper jaw. This nerve provides sensory information for portions of your:

• Nasal cavity.
• Sinuses.
• Maxillary teeth (the teeth in your upper jaw).
• Palate.
• Middle portion of your face and skull — the area below your eyes and above your mouth.

Mandibular nerve branch function

“Mandibular” refers to your lower jaw. This nerve branch is the largest of the three and has both sensory and motor fibers. It provides sensory innervation of:

• The inner lining of your cheeks (buccal mucosa).
• The floor of your mouth.
• Your mandibular teeth (the teeth in your lower jaw).
• Your tongue.
• The skin below your mouth.

The motor portion provides movement information to all the muscles involved in chewing (mastication). These include your:

• Masseter muscles.
• Temporalis muscles
• Pterygoid muscles.

Your mandibular nerve also plays a role in swallowing by supporting your digastric muscle and mylohyoid muscle.

Where is the trigeminal nerve?

You have two trigeminal nerves, one on each side of your head. They start in your brain and travel throughout your head, splitting into three branches.

What is the anatomy of the trigeminal nerve?

The structure (anatomy) of your trigeminal nerves resembles tree branches extending from your brain throughout your face. Here’s what that looks like:

1. The trigeminal nerves begin within four nuclei — or collections of nerve cell bodies — in your brain. Three of these nuclei are responsible for sensory information. The fourth controls motor (movement) function.
2. These three sensory nuclei merge to become one sensory root near the pons, which is the largest, central part of your brainstem.
3. This sensory root becomes the trigeminal ganglion as it leaves your brainstem on each side. (A ganglion is a cluster of nerve cell bodies in your peripheral nervous system.) Each trigeminal ganglion is near your temple at the side of your head, in front of your ear. It’s located within Meckel’s cave, a space filled with cerebrospinal fluid between two layers of dura mater over your temporal bone.
4. The trigeminal ganglion splits into three trigeminal nerve branches — the ophthalmic, maxillary and mandibular branches. These branches travel along each side of your head to different parts of it.

What conditions affect your trigeminal nerve?

Several conditions and situations can affect the functioning of your trigeminal nerve, like:

• Head trauma or brain conditions.
• Pressure from nearby blood vessels, tumors or swelling.
• Inflammation from certain infections, like the herpes zoster virus (the virus that causes shingles).
• Circulatory issues, like microvascular disease.
• Autoimmune conditions, like scleroderma and Sjögren’s syndrome.
• Accidental damage from brain, facial or dental surgery.

Specific conditions related to issues with your trigeminal nerve include:

• Trigeminal neuralgia: This is a chronic pain disorder that causes episodes of intense facial pain. It typically happens when a blood vessel puts pressure on your trigeminal nerve near your brainstem.
• Trigeminal neuropathy: This is an umbrella term for nerve damage (neuropathy) that affects your trigeminal nerve. It typically causes symptoms like numbness, pain or other abnormal sensations (paresthesia).
• Cluster headache: This is pain on one side of your head that lasts from 15 minutes up to three hours. The pain occurs daily for weeks to months, often happening at the same time each day and up to eight times per day. Irritation or inflammation of part of your trigeminal nerve may play a role in cluster headaches.
• Lateral medullary syndrome (Wallenberg syndrome): This condition happens after an event that affects how blood flows to your brainstem like a stroke or blood clot. It affects the function of your trigeminal nerve and leads to symptoms like difficulty swallowing, dizziness and involuntary eye movements.

Treatment for trigeminal nerve issues depends on the underlying cause. Your trigeminal nerve can often recover from minor damage with time. In rare cases, you may need surgery to reconnect severed nerves. Some people need a nerve graft to replace the damaged nerve with a healthy one.

What are the symptoms of trigeminal nerve damage?

The symptoms of trigeminal nerve damage vary significantly due to the large size of the nerve and its various functions. A trigeminal nerve injury may affect a small area (like part of your gum) or a large area (like one side of your face). It depends on where the nerve has damage.

Examples of signs and symptoms of trigeminal nerve damage include:

• Facial numbness or tingling.
• Facial pain.
• Corneal abrasions.
• Vision issues.
• Jaw muscle spasms or weakness.
• Difficulty chewing, speaking or swallowing.

See a healthcare provider if you have any of these symptoms.

How can I keep my trigeminal nerve healthy?

You can’t always prevent trigeminal nerve damage. But these steps can help keep your nervous system — including your trigeminal nerve — healthy:

• Eat nutritious foods, especially those with vitamin D and vitamin B12. These vitamins support nerve health.
• Manage chronic conditions that can damage nerves, like diabetes and high blood pressure.
• Seek help to quit smoking. Tobacco use slows blood flow to your nerves.
• Reach and maintain a weight that’s healthy for you.
• Decrease stress through meditation, walking or other healthy techniques.