Facial Nerve Anatomy

Family enjoying pasta

The next time you enjoy a delicious treat, you can thank your facial nerve for allowing you to taste and smile about it. This nerve, also referred to as the seventh cranial nerve, controls taste sensation for the front two-thirds of the tongue as well as the muscles you use to make facial expressions.

Location and Function

The seventh cranial nerve originates in the brain stem and travels through the base of the skull to transmit information to and from the facial structures, explains Stanford Medicine. The nerve exits the skull at an opening in the bone near the base of the ear called the stylomastoid foramen.

The nerve branches off into a number of fibers that provide sensation to different oral and facial structures. According to the Yale School of Medicine, the seventh cranial nerve has four main components with unique functions:

  • Branchial Motor

    These fibers make up the largest component of the nerve and supports the muscles responsible for facial expression.
  • Visceral Motor

    This component controls the salivary glands, which provide saliva, and the hard and soft palates.
  • Special Sensory

    This portion of the nerve provides taste sensation to the front two-thirds of the tongue.
  • General Sensory

    This component provides general skin sensation to parts of the ear.

Causes of Facial Nerve Problems

Stanford Medicine reports that damage to the seventh cranial nerve can result in a number of problems, depending on which nerve branch has been affected. Impairment of the nerve may temporarily paralyze certain muscles in the face, affect a person's speech or cause difficulty eating and drinking.

The most common condition affecting the function of the facial nerve is Bell's palsy, which accounts for nearly 50 percent of facial paralysis cases, according to Stanford Medicine. Other medical conditions that may impair the facial nerve include Lyme disease, salivary gland tumors, stroke and trauma, such as a skull fracture. Very rarely, nerve paralysis may result from dental treatment involving local anesthesia, according to a report in the Journal of Oral and Maxillofacial Radiology.

Facial Paralysis and Bell's Palsy

A person with Bell's palsy will often experience sudden weakness in their facial muscles. Half of their face may appear to droop, and they may have trouble making facial expressions. According to the Mayo Clinic, this muscle weakness is associated with swelling or inflammation of the facial nerve, though the exact cause is not known. In most cases, the paralysis is temporary and doesn't come back later in life.

Medical and dental professionals can work together to resolve concerns with the function of the seventh cranial nerve. A doctor will take tests to determine whether your muscle weakness is related to Bell's palsy or another condition and recommend appropriate treatment. They may suggest physical therapy or medications to assist in recovery and ensure no further damage is done to the nerve, reports the Mayo Clinic.

Oral Hygiene Maintenance

Facial paralysis may make it difficult to brush and floss properly, especially on the affected side of the face, explains Facial Palsy UK. Therefore, it's important for patients with facial nerve damage to pay special attention to their oral hygiene. Additionally, some issues with the seventh cranial nerve may affect saliva production and lead to dry mouth.

Any patient who has experienced facial paralysis in the past should inform their dentist. With professional attention and a regular oral care routine of brushing twice a day and flossing daily, the patient can ensure their mouth stays healthy while they receive treatment to address the nerve problem.

This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to be a substitute for professional advice, diagnosis or treatment. Always seek the advice of your dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.

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