Muscles Affected
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Occipitofrontalis
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Actions: Draws scalp anteriorly or posteriorly. It can raise eyebrows, and wrinkle the skin of the forehead horizontally as in look of surprise.
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Orbicularis oculi
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Actions: Closes eyes.
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Orbicularis oris
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Actions: Closes and protrudes lips, as in kissing; compresses lips against teeth; and shapes lips during speech.
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Buccinator
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Actions: Presses cheeks against teeth and lips, as in whistling, blowing, and sucking; draws corner of mouth laterally; and assists in mastication (chewing) by keeping food between the teeth (and not between teeth and cheeks).
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Platysma
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Actions: Draws outer part of lower lip inferiorly and posteriorly as in pouting; depresses mandible.
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Mechanism of Bell’s Palsy
Bell’s palsy is defined as a condition wherein a part of an individual’s face muscles weakens. As with patient AM’s facil condition it is evident that there is muscle weakness on the left side of his face. The weakening of the muscles in the face is caused by the dysfunction of the innervations of the muscle, most prominently, facial (VII) nerve.
Other symptoms
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Difficulty of closing eyelids
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Loss of facial sensation
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Disordered movement of muscles
References:
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Taylor, D. C. (2023, June 13). Bell’s Palsy. Practice Essentials, Background, Anatomy. https://emedicine.medscape.com/article/1146903-overview#:~:text=The%20facial%20nerve%20passes%20through,%2C%20buccinator%2C%20and%20platysma%20muscles.
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Tortora, G. J., & Derrickson, B. (2017). Principles of anatomy and physiology (15th ed.). Wiley Custom Learning Solutions.
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U.S. Department of Health and Human Services. (n.d.). Bell’s Palsy. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/bells-palsy#:~:text=Bell’s%20palsy%20is%20the%20most,with%20taste%20and%20ear%20sensation).