This is patient AM, 28-year-old male who came in the ER because of drooping of his left face. He said he woke up and he could not move his left face.
He has no other muscle weakness. He is conscious and coherent although he had a little difficulty speaking because the left side of his lips drooped. He had normal blood pressure and he had no other co-morbidities. He was diagnosed to have Bell’s palsy. Name 5 muscles which are affected and list its actions. Describe the mechanism of his muscle weakness. What other symptoms could the patient exhibit as a result of facial muscle weakness?
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Muscles:
- Frontalis
- Action: Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally
- Orbicularis oris
- Action: Closes and protrudes lips; compresses lips against teeth; and shapes lips during speech
- Orbicularis oculi
- Action: closes the eyelids and assists in pumping the tears from the eye into the nasolacrimal duct system
- Buccinator
- Action: Presses cheeks against teeth and lips; draws corner of mouth laterally; and assits in mastication (chewing) by keeping food between the teeth (and not between teeth and cheeks)
- Plastyma
- Action: Draws outer part of lower lip inferiorly and posteriorly; depresses mandible
- Frontalis
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Mechanism of Muscle Weakness:
- The facial nerve is damaged by inflammation within the nerve causing it to become enlarged, at the point where the nerve exits the skull through the stylomastoid foramen. Ischemia occurs as the nerve swells in its bony canal, blocking neural blood supply.
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Other symptoms:
- Drooping of the mouth, drooling, inability to close eye (causing dryness of the eye), excessive tearing in one eye, facial pain or abnormal sensation, altered taste, and intolerance to loud noise.