Question

Lesions to CN X (vagus) result in deviation of the uvula away from the side of the lesion. What happens to the weak side and the direction in which the uvula points?

1) The weak side collapses and the uvula points away from the lesion
2) The weak side collapses and the uvula points towards the lesion
3) The weak side remains unaffected and the uvula points away from the lesion
4) The weak side remains unaffected and the uvula points towards the lesion

Answer 1

Lesions to the CN X (vagus nerve) result in the uvula pointing away from the lesion because the muscle on the affected side is weak and collapses, which leads to uvular deviation towards the stronger side.

Step-by-step explanation:

Lesions to the CN X (vagus nerve) result in a characteristic clinical sign where the uvula deviates away from the side of the lesion. The uvula points towards the side with intact muscle function because the muscle on the affected side (weak side) cannot contract effectively to center the uvula. Consequently, the weak side collapses or has reduced muscular function. This means, in response to the given choices, that the weak side collapses and the uvula points towards the lesion should be the other way around:

1. The weak side collapses and the uvula points away from the lesion.

This uvular deviation can be observed when the patient is asked to open their mouth and say 'ah', which normally prompts the elevation of the palate. This clinical sign helps differentiate the side of the neurological deficit, aiding in diagnosis. It can be a part of neurological examinations when brainstem lesions are suspected. In the given scenario presented, the uvula would deviate towards the stronger side, which is not affected by the lesion, indicating muscle weakness on the opposite side.