5 muscles affected:
1. Orbicularis oculi- closes the eye
2. Orbicularis oris- Closes and protrudes lips, as in kissing; compresses lips against teeth; and shapes lips during speech.
3. Frontalis- raises eyebrows, and wrinkles skin of forehead horizontally
4. Buccinator- Presses cheeks against teeth and lips, as in whistling, blowing, and sucking; draw corner of mouth laterally; and assists in mastication by keeping food between the teeth
5. Platysma- Draws outer part of lower lip inferiorly and posteriorly as in pouring; depresses mandible
Mechanism of Weakness
The mechanism behind the muscle weakness is due to the disorder in the facial or seventh cranial nerve. The paralysis in this nerve makes the facial muscles on one side of the face unresponsive causing sagging of the muscle nerves physically appearing as total drooping of the face.
Other symptoms of Bell’s palsy may include:
- Headache
- Loss of taste
- Changes in the amount secretion of tears and saliva
- Increased sensitivity to sound on the affected side
- Pain around the jaw or in or behind the ear on the affected side
- In rare cases, Bell’s palsy can affect the nerves on both sides of your face.
References:
Tortora, G. J., & Derrickson, B. (2011). Principles of anatomy & physiology. (13th ed., pp. 376-377). Danvers, MA, Wiley.
Bell's palsy - Symptoms and causes. (2022, May 4). Mayo Clinic. Retrieved September 23, 2022, from https://www.mayoclinic.org/diseases-conditions/bells-palsy/symptoms-causes/syc-20370028