Facial nerve


The lower portion of the pons contributes the nuclei which produces the facial nerve. The facial nerve takes a path along the petrous portion of the temporal bone to come out along the side of the face nearly adjacent to the salivary gland, also known as the parotid gland.

This mixed nerve is responsible for sending impulses that control the posterior belly of the digastric muscle and the facial expression muscles including the scalp muscles and platysma muscles, through its motor impulses. The lacrimal gland, the submandibular and sublingual glands are able to receive a specific amount of parasympathetic autonomic motor innervation from the facial nerve.


The taste buds on the back two thirds of the tongue yield the origins of the sensory fibers for the facial nerve. The taste buds, while not originally considered to have receptor qualities in the most directive sense, are of course the chemoreceptors for the facial nerve, as they are the primary receptors which discern chemical stimuli.


Facial nerve
Image: Facial nerve

Just prior to the point where the facial nerve makes its entrance to the pons, there lies an enlargement which has been determined to be the geniculate ganglion.


When the sensations that register taste are acknowledged, they are sent via the impulses to the nuclei within the medulla oblongata, through the thalamus, and pulsate onward to reach their ultimate destination, the gustatory section within the parietal lobe of the cerebral cortex.

Damage to the facial nerve can result in a host of different issues, including the loss of taste (particularly related to the sensation that registers tastes regarding sweets) and the inability to control or contract the muscles in the face, causing a loss of facial expression. Many patients who experience damage to the facial nerve also experience facial sagging as a result of lost muscle tone.

There is a functional disorder which is probably viral in nature, that cause these symptoms along with the loss of the facial nerve’s effectiveness, known as Bell’s palsy.
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