1. Muscles Affected:
- Orbicularis oris
- Action: Closes lips, compresses lips against teeth, protrudes lips, and shapes lips during speech
- Zygomaticus
- Action: Draws angle of mouth upward and outward as in smiling or laughing
- Levator palpebrae superiosis
- Action: Elevates upper eyelid
- Buccinator
- Action: Major cheek muscle; compresses cheek as in blowing air out of mouth and causes cheeks to cave in, producing the action of sucking
- Platysma
- Action: Draws outer part of lower lip downward and backward as in pouting; depresses mandible
2. Mechanism
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- Bell's palsy, also known as "acute peripheral facial palsy with unknown cause," is the weakening of facial muscles on one side of the face. It causes half of the face to look droopy, affecting smiles and the closing of eye.
3. Other Symptoms
- Drooling
- Headache
- Pain around jaw or behind ear
References:
Mayo Clinic. (2022, May 4). Bell’s palsy. https://www.mayoclinic.org/diseases-conditions/bells-palsy/symptoms-causes/syc-20370028#
Tortora, G. J., & Grabowski, S. R. (1993). Principles of Anatomy and Physiology (7th ed.). HarperCollins College.