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A 50 year-old male complained of weakness on the right half of his face, which quickly led to the facial paralysis of this side. He was unable to wrinkle his forehead, smile, show his teeth. He was also unable to close his right eye. Taste perception was distorted over the left anterior portion of the tongue. There was complete recovery of the facial weakness and taste distortion within two months.

i) Which cranial nerve is involved?
ii) Why it causes paralysis on the right?
iii) How would you differentiate this condition from other cranial nerves involvement?

Solution Preview

I am sure you know that there are 12 pairs of cranial nerves in human. The 7th pair is the facial nerve and it emerges from the brainstem between the pons and the medulla. The function of this pair of nerves is to control the muscles in the face resulting in various facial expressions and imparts the sensation of taste in the anterior 2/3rd part of the tongue and controls the muscles of the inner ear.

The facial nerve is divided into 5 branches such as temporal, zygomatic, buccal, marginal mandibular and cervical branches. The facial nerve nucleus is branchial in origin and is located in the ...