The facial nerve and its branches regulate a number of functions of the mouth and face.
Most of its divisions stimulate muscles that allow eyelids to open and close, as well as facial movements.
The facial nerve is the seventh of the12 cranial nerves.
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Bells palsyis the most common medical problem involving theseventh cranial nerve.
Anatomy
The facial nerve has a complex anatomy.
Each of the motor nerve branches signals a different set of muscles to move.
Some muscles are controlled by more than one branch, and some branches control more than one muscle.
The brainstem is the part of the brain that is continuous with thespinal cord.
The nerve continues in the internalauditory canalnear the ear as the meatal segment.
As it travels near the structures of the ear, the labyrinthine segment is the shortest segment.
The tympanic segment runs through the bones of the middle ear.
These differences may be picked up when detailed imaging studies are performed for a medical reason.
Variations can be challenging when it comes to surgical procedures that involve the facial nerve.
Sensory
The facial nerve detects sensation from the small area behind the ear described as the auricle.
Parasympathetic
Nerve branches of the facial nerve simulate glands in the face.
The lacrimal glands are located around the eyes.
These glands regularly produce small amounts oftearsto lubricate and protect the eyes.
They also produce more tears when a person cries.
And thesublingual glandsin the lower part of the mouth produce saliva as well.
Parasympathetic branches of the facial nerve also stimulate mucous glands of the nose.
Associated Conditions
There are a few medical conditions that result in decreased function of the facial nerve.
The symptoms typically involve weakness of the face because most branches of the facial nerve control facial movement.
However, impairment of any of the other three components of facial nerve function can occur as well.
Bells palsy can be very distressing, often causing trouble speaking or even chewing.
One eye can become dry, red, and irritated because it can be difficult to shut the eyelid.
Tear production can be impaired as well.
Stroke
A stroke is an interruption of blood flow in the brain.
In those cases, the entire side of the face will get weak, like with Bell’s palsy.
However, a stroke is a serious condition requiring urgent medical attention.
Shingles affecting the facial nerve is described as Ramsay Hunt syndrome.
The symptoms of Ramsay Hunt syndrome include face weakness and a skin rash on one side of the face.
This condition can also cause decreased sensation, dizziness, or hearing loss.
This syndrome can begin suddenly and it may be fatal due to the weakness of the breathing muscles.
Facial nerve reconstruction and grafting are methods that have been used to repair a damaged facial nerve.
These procedures may improve motor function for some facial nerve injuries.
Techniques include stereotactic and minimally invasive procedures, as well as more extensive open procedures.
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