Muscles Affected by Bell’s Palsy
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Frontalis - raise eyebrows, facial weakness in general, & wrinkle forehead
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Orbicularis oris - closes, protrudes & compresses the lips against teeth
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Orbicularis oculi - the orbicularis oculi muscle aids in the closure of the eyelids
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Buccinator - pressing cheeks against teeth & lips and drawing corner of mouth laterally
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Platysma muscles - tenses the skin of the anterior neck & depresses mandible and lower lip
Mechanism of Muscle Weakness
Bell's palsy is a disorder that causes muscular weakness on one side of the face. It's a nerve disease that controls the movement of the muscles of the face. A viral or bacterial infection damages the facial (VII) nerve. It begins right away and worsens over 48 hours. In most situations, the weakness is just transient and recovers considerably over a few weeks. Because of the weakness, half of the face seems to droop. Smiles are one-sided, and the afflicted eye refuses to close.
Other symptoms may include: altered taste, dry eye and mouth, drooling, sensitivity to sound, an inability to make facial expressions, such as smiling or frowning, and difficulty pronouncing certain words.