Name 5 muscles which are affected and list its actions.
1. Frontalis
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It produces facial expressions by raising the brows and wrinkling the skin on the forehead. It also aids in the lifting of the eyelids.
2. Orbicularis Oculi
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Closes the eye and the palpebral region's both voluntary and involuntary functions (blinking).
3. Orbicularis Oris
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It tightens the muscle, puckers the lips, and conceals the mouth.
4. Buccinator
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It tightens the muscle by compressing the cheeks against the teeth (mastication and whistling).
5. Platysma
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When teeth are clenched, it draws the corners of the mouth downward, depresses the lower jaw, and tenses the skin of the neck.
Describe the mechanism of his muscle weakness.
This condition is caused by abnormalities in a person’s facial nerve or cranial nerve VII. It affects the muscles on one side of the face. Due to the fact that Bell's palsy is related to viral infection, it temporarily prevents the nerve from transmitting signals to the muscles, causing weakness or paralysis. The most common symptoms include difficulty controlling the blinking of the eyes as well as facial expressions.
What other symptoms could the patient exhibit as a result of facial muscle weakness?
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Dry eyes, facial/ear pain, loss of taste, headache, changes in the amount of tears and saliva
References:
Tortora, G. J., & Derrickson, B. H. (2018). Principles of anatomy and physiology. John Wiley & Sons.
https://www.mayoclinic.org/diseases-conditions/bells-palsy/symptoms-causes/syc-20370028 (“Bell's palsy - Symptoms and causes”)