5 MUSCLES INVOLVED:
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Occipitofrontalis
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Action: Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally as in look of surprise
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Orbicularis oculi
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Action: Closes eye
- Orbital part: closes eyelids tightly
- Palpebral part:closes eyelids gently
- Deep palpebral part: compresses lacrimal sac
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Orbicularis oris
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Action: Closes and protrudes lips, as in kissing; compresses lips against teeth; shapes lips during speech
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Buccinator
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Action:
- 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 the teeth and cheeks)
- Maintains the tightness of the cheeks and presses them against the teeth during chewing
- Assists the tongue to keep the bolus of food central in the oral cavity.
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Platysma
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Action: Draws outer part of lower lip inferiorly and posteriorly as in pouting; depresses mandible
Mechanism:
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The nerve that controls facial muscles passes through a narrow corridor of bone on its way to the face. In Bell's palsy, that nerve becomes inflamed and swollen — usually related to a viral infection. Besides facial muscles, the nerve affects tears, saliva, taste and a small bone in the middle of the ear.
Other Symptoms:
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Loss of feeling in the face
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Headache
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Tearing
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Drooling
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Loss of the sense of taste on the front two-thirds of the tongue
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Hypersensitivity to sound in the affected ear (hyperacusis)
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Inability to close the eye on the affected side of the face
References:
Facn, D. C. T. D. M. (n.d.). Bell Palsy: Practice Essentials, background, anatomy. https://emedicine.medscape.com/article/1146903-overview#:~:text=These%20nerves%20serve%20the%20muscles,%2C%20buccinator%2C%20and%20platysma%20muscles.
Professional, C. C. M. (n.d.). Bell’s Palsy. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/5457-bells-palsy
Tortora, G. J., & Derrickson, B. H. (2017). Tortora’s Principles of Anatomy & Physiology. Wiley.