A patient asks to say 'Aaah' and notices the uvula deviates to the left. This suggests a lesion to which nerve?

A patient asks to say 'Aaah' and notices the uvula deviates to the left. This suggests a lesion to which nerve?

• A. Right Glossopharyngeal (CN-IX)
• B. Left Glossopharyngeal (CN-IX)
• C. Right Vagus (CN-X)
• D. Left Vagus (CN-X)

Answer: (D)

When a patient says “Aaah,” the soft palate should elevate evenly because the palatal muscles are innervated by the vagus nerve. In a unilateral vagus nerve palsy, the muscles on the affected side are weak, so the intact side pulls the uvula toward itself. The result is the uvula deviating away from the side of the lesion. If the uvula deviates to the left, the lesion is on the right vagus nerve. The glossopharyngeal nerve (involved in the gag reflex and some swallowing functions) doesn’t produce a simple uvula deviation, so those nerves don’t explain this sign.

When a patient says “Aaah,” the soft palate should elevate evenly because the palatal muscles are innervated by the vagus nerve. In a unilateral vagus nerve palsy, the muscles on the affected side are weak, so the intact side pulls the uvula toward itself. The result is the uvula deviating away from the side of the lesion.

If the uvula deviates to the left, the lesion is on the right vagus nerve. The glossopharyngeal nerve (involved in the gag reflex and some swallowing functions) doesn’t produce a simple uvula deviation, so those nerves don’t explain this sign.