Muscles Affected by Bell's Palsy
- platysma- draws outer part of lower lip inferiorly and posteriorly; depresses mandible
- buccinator- compresses the cheeks against the teeth during mastication and whistling
- frontalis- moves up the scalp, raises the eyebrows, and wrinkles the skin of the forehead horizontally.
- orbicularis oris- compresses, closes, and protrudes lips
- orbicularis oculi- closing of eyes and blinking
Mechanism of Muscle Weakness
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.
Other Symptoms
- Drooling and difficulty in swallowing
- speech difficulty
- headaches
- loss of sense of taste
- jaw pain
Reference: Tortora, & Derrickson. (2012). Chapter 11: The Muscular System. In Principles of anatomy and physiology (13th ed.)