Affected Muscles
- Orbicularis oris: Closes and protrudes lips, as in kissing; compresses lips against teeth; and shapes lips during speech.
- Buccinator: Presses cheeks against teeth and lips, as in whistling, blowing, and sucking; draws corner of mouth laterally; and assists in mastication (chewing) by keeping food between the teeth (and not between teeth and cheeks).
- Risorius: Draws angle of mouth laterally, as in grimacing.
- Orbicularis oculi: Closes eye.
- Corrugator supercilii: Draws eyebrow inferiorly and wrinkles skin of forehead vertically as in frowning.
Mechanism of Bell's Palsy
- Bell’s palsy, also known as facial paralysis, is a unilateral paralysis of the muscles of facial expression. It is due to damage or disease of the facial (VII) nerve. Possible causes include inflammation of the facial nerve due to an ear infection, ear surgery that damages the facial nerve, or infection by the herpes simplex virus. The paralysis causes the entire side of the face to droop in severe cases. The person cannot wrinkle the forehead, close the eye, or pucker the lips on the affected side. Drooling and difficulty in swallowing also occur. Eighty percent of patients recover completely within a few weeks to a few months. For others, paralysis is permanent. The symptoms of Bell’s palsy mimic those of a stroke.
Other Symptoms of Bell's Palsy
- Drooling from one side of your mouth
- Difficulty closing an eyelid, which causes eye dryness
- Facial pain or abnormal sensations
- Excessive tearing in one eye
- Problems with taste
- Low tolerance for loud noises
- Pain around the jaw and behind the ear
- Problems eating or drinking
References:
National Institute of Neurological Disorders and Stroke. (2023, February 7). Bell’s Palsy. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/bells-palsy
Tortora, G. J., & Derrickson, B. H. (2020). Principles of Anatomy and Physiology (16th ed.). John Wiley & Sons, Inc.