The Facial Nerve
The “facial nerve” is a the proper term for a specific nerve, not just a nerve of the face, as the name might suggest. The trigeminal nerve (cranial nerve v), for example, provides general sensation for much of the face and controls the muscles used for chewing, but is a different nerve from “The” facial nerve, cranial nerve VII. the facial nerve mainly serves to move muscles of the face.
Anatomy and function
The facial nerve and facial muscles.
The facial nerve, also known as cranial nerve VII, is the nerve controlling the muscles of facial expression, including raising the eyebrows, closing the eyes, smiling or closing the lips. Each side of the face has seventeen muscles innervated by branches of the 7th cranial nerve, called the facial nerve. Problems with this nerve may lead to weakness of one or more of these muscles.
Originating from the brainstem, this nerve exits the skull base below the ear, passes through the parotid gland, where it branches out and innervates the muscles of facial expression on that side of the face. The branching pattern is quite variable from person to person.
A branch of the facial nerve, named the chorda tympani, takes off from the main trunk of the facial nerve as it passes through the middle ear, making its way to the tongue from which it conveys sensation of taste to the brain.
Facial nerve weakness or paralysis
The left or right facial nerve may become weak or paralyzed due to trauma, infection, or stroke. Branches of the facial nerve allow for blinking and closing of the eyelids, moving the lips for speech and eating, as well as for facial expression. If the eyelid is unable to close well, the eye (especially the cornea) may dry out and cause irritation or even loss of vision.
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