A. 5 muscles affected
1. Frontalis
Actions: Elevates the eyebrows and wrinkles the forehead
2. Orbicularis oculi
Actions: Closes the eyelids
3. Orbicularis oris
Actions: Purses the lips
4. Buccinator
Actions: Pulls the corner of mouth laterally; presses the cheek against the teeth
5. Platysma
Actions: Draws the corners of the mouth down; it aids in depression of the mandible
B. Mechanism of muscle weakness
Bell's palsy occurs when one of the nerves that controls muscles in the face become injured or stops working properly. It results from a problem in cranial nerve VII, also called the facial nerve, connecting the brain to the muscles that control facial expressions.
C. Other symptoms
- Drooling
- Dry eyes
- Difficulty speaking, eating, or drinking
- Facial or ear pain
- Headache
- Loss of taste
- Ringing in your ears (tinnitus)
- Sensitivity to sounds (hyperacusis)
References
Bell’s Palsy. (2024, August 8). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/5457-bells-palsy#symptoms-and-causes
Bell’s Palsy. (n.d.). National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/bells-palsy
Univ of Michigan - Gross Anatomy - Muscles Tables. (n.d.). Copyright 2000 the University of Michigan. https://www.med.umich.edu/lrc/anatomy-tables/muscles_alpha.html