Your brainstem hosts multiple cranial nerves. The facial nerve is the seventh cranial nerve. It controls your facial movements and expressions. The nerve fibers controlled by your facial nerve also involve your tongue and tear production. The facial nerve affects several other muscles and can moderate your sensitivity to sound volume.
What Is the Facial Nerve?
The facial nerve is the seventh of the twelve cranial nerves and operates out of your brainstem. Your facial nerve is responsible for making facial expressions, and it stimulates the sensors in the front two-thirds of your tongue. The facial nerve also helps to stimulate your oral cavity and lacrimal glands.
Your facial nerve originates in your brain stem and connects to the pons, which the nerve travels through to reach your face. Your facial nerve goes through your temporal bone and emerges from your stylomastoid foramen.
What Does the Facial Nerve Do?
The facial nerve has four primary functions. The first function is to provide motor instructions to your facial muscles. These signals instigate facial expressions.
The second primary function is to provide a pathway for your facial nerves to the salivary and lacrimal glands.
The third function is giving you sensation at the front of your tongue.
The last primary function of the facial nerve is to provide sensation to the skin around your ear.
Where Is the Facial Nerve Located?
The seventh cranial nerve starts in your brainstem and then travels through the base of your skull near the eighth cranial nerve. Once your facial nerve is past the ear, it enters your face through a bone at the bottom of your ear. From there, the facial nerve branches out near a major salivary gland.
What Are the Facial Nerve Branches?
Your facial nerve stimulates many parts of your head and neck. Three nuclei comprise the facial nerve: the central motor nucleus, the parasympathetic nuclei, and the sensory nucleus.
These three parts of the facial nerve send messages throughout your glands and head. When the facial nerve sends a message, that signal can branch into one of five divisions. These branches input information into a group of muscles that regulate facial expressions. Overlap between the branches is common.
Frontal branch. This branch sends information to your forehead muscles.
Zygomatic branch. This branch goes to the muscles involved in conscious eye closure.
Buccal branch. This nerve sends information to the muscles that control your nostrils, upper lip movement, spontaneous blinking, and raising of the corner of your mouth to smile.
Marginal mandibular branch. Information on this branch goes to muscles that control lowering your lower lip.
Cervical branch. This branch goes to your lower chin muscle and lowers the corners of your mouth.
Signs Something Could Be Wrong With Your Facial Nerve
Facial nerve paralysis indicates a significant problem with your facial nerves. If you lose the ability to smile, blink, or make other facial movements, you may have facial nerve paralysis. In many cases, this condition only affects one side of your face, though.
If your facial nerve becomes inflamed or damaged, it can affect your control over muscle groups in your:
Symptoms may include drooping skin around the muscle groups you can't control as the muscles relax, providing no motor function. Other facial nerve problems can also occur because of facial nerve paralysis.
What Conditions Affect the Facial Nerve?
The potential result of temporary restriction of facial blood flow, Bell's palsy is the most common cause of facial nerve paralysis. Bell's palsy can develop quickly without warning and only affects one side of your face.
Typically, though, the facial nerve recovers. Facial paralysis often goes away within a year.
A traumatic head injury is another condition that causes one-sided facial nerve paralysis. If you experience head trauma that damages your seventh cranial nerve, you may lose complete control over the muscles on one side of your face. A stroke caused by a lack of blood flow to your brain stem can similarly damage the facial nerve.
Other conditions that can affect the facial nerve include:
Injury in different branches of your facial nerve can have different results. If your frontal branch is injured, you may have paralysis in your forehead or be unable to move your eyebrow. Trauma to your zygomatic branch, on the other hand, can make it hard for your body to force your eye closed.
Trauma can make smiling and moving your mouth difficult if your buccal branch is affected. This also affects your speech due to the inability to move your lips and make sounds. Your nostrils may become paralyzed, making breathing difficult too. Trauma to your marginal mandibular branch makes eating and drinking harder.
The cervical branch doesn't typically affect vital functions of your face, though, even if you have trauma or impairment in this area.
How to Protect Your Facial Nerve
Protecting your facial nerve means safeguarding your face and head from illness or a traumatic injury. Inflammation, swelling, and injury can cause damage to the soft-tissue planes related to the facial nerve branches.
Unfortunately, the exact location of facial nerve branches is different from person to person. This makes avoiding them in surgery more challenging. Surgeries that cause complications include facelifts.
In the case of facial nerve paralysis, you can work with your doctor for access to facial retraining and facial reanimation. Specialized physical therapists will create a treatment plan to help you develop movement and coordinate muscles in your face. This rehabilitation can help you reestablish your facial functions.