5 muscles affected
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Buccinator
Action: Compresses cheek against molar teeth
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Orbicularis Oculi
Action: Closes the eyelids
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Frontalis
Action: Raises the eyebrows and wrinkles the forehead
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Risorius
Action: Extends angle of mouth laterally
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Mentalis
Action: Elevates and protrudes lower lip, wrinkles skin of chin
Mechanism of Muscle Weakness
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His muscle weakness is mainly on the Orbicularis Oculi which causes the drooping of his eye. His risorius is also affected which causes the drooping of the left side of his lips. He is also having a hard time speaking because of the weakness of his Mentalis muscle. Patients with Bell’s Palsy develop unilateral facial paralysis which results in muscle weakness on one side of the face. The cause of facial muscle weakness or paralysis is thought to be the inflammation affecting the body’s immune system.It usually resolves on its own and causes no complications.
Other symptoms he may experience due to facial muscle weakness are:
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Pain around the jaw
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Headache
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Loss of taste
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Pain behind the ear of the affected side
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Drooling
Reference: Tortora, G. J., & Derrickson, B. (1975). Principles of Anatomy & Physiology. http://ndl.ethernet.edu.et/bitstream/123456789/1717/1/36%2c2012.pdf.pdf