Affected Muscles due to Bell’s palsy:
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Orbicularis oris - Closes and protrudes lips, compresses lips against teeth, and shapes lips during speech
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Orbicularis oculi - Closes eye
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Zygomaticus major - Draws angle of mouth superiorly and laterally, as in smiling
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Buccinator - Presses cheeks against teeth and lips, as in whistling, blowing, and sucking; draws corner of mouth laterally; and assists in mastication by keeping food between the teeth
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Platysma - Draws outer part of the lower lip inferiorly and posteriorly as in pouting and depresses the mandible
Mechanism of Muscle Weakness:
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Bell's palsy is often associated with swelling and inflammation of the facial nerve (cranial nerve VII) which controls the muscles of facial expression. This leads to disruption of the nerve’s ability to transmit signals to these muscles.
Other Symptoms:
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Drooling
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Eye dryness
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Difficulty in eating and drinking
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Headache
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Loss of taste