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The Facial Nerve

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Facial Nerve

The facial nerve is a long and complicated structure. It starts in the brain in the facial nucleus and the fibers coalesce into a discrete nerve in the middle cranial fossa. They form a complex along with the nerves of balance and hearing, and enter the temporal bone through a small opening in the bone. Here the nerve gives off a branch which re-enters the brain and ultimately winds its way back to the tear gland above each eye. The facial nerve then splits off independently from the other nerves and passes very close to the inner ear and the stapes (the stirrup bone within the middle ear behind the ear drum). It gives off a branch to the taste buds on the tongue, and another small nerve branch to the one of the small muscles within the middle ear, which acts like a sound dampener. The nerve then continues down completely through the temporal bone and mastoid (the bone immediately behind the external ear) and exits into the soft tissue of the face below the external ear. It quickly enters the parotid gland (the large salivary gland which sits in front of the ear) and divides into multiple smaller branches. Each branch heads off to different regions of the face to electrically stimulate and control different facial expressions. There are literally hundreds of different expressions/visual signals that can be created by combining different and subtle facial muscle contractions.