Facial Nerve

What is the facial nerve?

Your facial nerve, also known as cranial nerve 7 and CN VII, is a nerve in your head that sends signals from your brain to parts of your face and vice versa. You have two facial nerves, one on each side of your head. Your facial nerves are the seventh set of 12 cranial nerve pairs in your nervous system.

You may not be thinking about it, but your facial nerves are constantly working. They’re responsible for many important functions that make you human, like forming countless facial expressions, talking, tasting and tear production.

What are the functions of the facial nerves?

Your facial nerves contain motor (movement), sensory and parasympathetic nerve fibers. Each of these types of nerve fibers has specific roles.

Facial nerve parasympathetic functions

The parasympathetic nerve fibers of your facial nerves control the salivary glands in your mouth and the lacrimal glands in the corners of your eyes. They trigger your salivary glands to release saliva (spit) and your lacrimal glands to release tears.

Facial nerve sensory functions

The sensory nerve fibers of your facial nerve play a key role in hearing. They provide innervation to your ear canal, tympanic membrane (eardrum) and outer ear (pinna). They also carry taste sensations from the front (anterior) two-thirds of your tongue.

Facial nerve motor branches

Your facial nerve has five branches that have distinct motor (movement) functions:

• Frontal (temporal) branch: Controls your forehead muscles.
• Zygomatic branch: Helps you close your eyes.
• Buccal branch: Allows you to move your nose and blink. It also makes it possible to raise your upper lip and the corners of your mouth to make a smile.
• Marginal mandibular branch: Draws your lower lip down (like a frown). It also travels through your middle ear to your stapedius muscle, which helps your inner ear respond to loud noises.
• Cervical branch: Allows movement in your chin and the lower corners of your mouth by controlling the platysma muscle in your neck.

What is the anatomy of the facial nerve?

Each of your facial nerves extends from your brain throughout your face like tree roots. The structure (anatomy) of your facial nerves:

• Starts in your brainstem.
• Travels through the base of your skull near the vestibulocochlear nerve (eighth cranial nerve).
• Enters your face through an opening in a bone near the base of your ear.
• Branches out through an opening near your parotid gland, a major salivary gland.

From there, the motor branches spread out to various parts of your face and into your neck.

What happens when the facial nerve is damaged?

When something damages your facial nerve, it doesn’t function as it should. This may cause specific movement or sensory issues, depending on which nerve fibers are damaged. Several conditions and situations can damage your facial nerves, like:

• Autoimmune conditions like Guillain-Barré syndrome and sarcoidosis.
• Salivary gland cancer and meningioma (skull base tumor).
• Ear infections or ear tumors like acoustic neuromas and schwannomas.
• Facial surgery, including cosmetic procedures like facelifts.
• Head trauma and facial fractures.
• Lyme disease.
• Stroke.

Facial nerve palsy

When a facial nerve is malfunctioning — especially the motor (movement) functions — healthcare providers often call it facial nerve palsy. “Palsy” means “paralysis.”

Two specific types of facial nerve palsy include:

• Bell’s palsy: This condition causes temporary facial paralysis. It usually only affects the muscles on one side of your face. You may have a lopsided smile or an eyelid that you can’t fully close.
• Ramsay Hunt syndrome: This is a complication of varicella-zoster virus infections, including chickenpox or shingles. It causes facial nerve paralysis and intense ear pain. It may also cause a painful rash on your ear, face or mouth.

Sometimes, the motor branches of your facial nerve become overactive, leading to frequent facial muscle twitches. This condition is called hemifacial spasm.

What are the symptoms of facial nerve palsy?

Symptoms of facial nerve palsy (paralysis) vary depending on the cause and which part of the nerve is affected. The symptoms may be temporary or permanent. You may experience:

• Facial muscle weakness in parts of or all of one side of your face.
• Facial muscle spasms.
• Drooping eyebrow and/or eyelid.
• Trouble closing your eyes or blinking.
• Dry eye due to loss of tear production.
• Decreased sound tolerance (hyperacusis) in one ear.
• Lopsided smile or facial appearance.
• Unclear speech or slurred speech.
• Difficulty eating and drinking.
• Diminished taste and dry mouth.

It’s important to see a healthcare provider if you have any of these symptoms. Many conditions can damage your facial nerves — some of which are serious. Your provider will diagnose the underlying cause.

How can I keep my facial nerves healthy?

You can’t always prevent facial nerve damage. But these steps can help keep your nervous system — including your facial nerves — 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.

It’s also important to protect your head and brain from injury. Wear a helmet when playing contact or extreme sports and when you ride a bike or motorcycle.