Which nerve is injured when tonsillar pillars sag and the uvula deviates?

Which nerve is injured when tonsillar pillars sag and the uvula deviates?

• A. Glossopharyngeal
• B. Hypoglossal
• C. Vagus
• D. Accessory

Answer: (C)

Unilateral injury to the vagus nerve impairs most of the muscles of the soft palate (via the pharyngeal plexus). When one side can’t elevate or tense the soft palate, that side sags, and the intact side pulls the uvula toward itself. So the uvula deviates to the healthy side. The tonsillar pillars appear to sag because the muscles of the soft palate on the injured side are not functioning properly. Other nerves listed don’t innervate the soft palate muscles responsible for lifting and tensing the palate (glossopharyngeal mainly provides sensory and a single pharyngeal muscle; hypoglossal to tongue muscles; accessory to trapezius/SCM).

Unilateral injury to the vagus nerve impairs most of the muscles of the soft palate (via the pharyngeal plexus). When one side can’t elevate or tense the soft palate, that side sags, and the intact side pulls the uvula toward itself. So the uvula deviates to the healthy side. The tonsillar pillars appear to sag because the muscles of the soft palate on the injured side are not functioning properly.

Other nerves listed don’t innervate the soft palate muscles responsible for lifting and tensing the palate (glossopharyngeal mainly provides sensory and a single pharyngeal muscle; hypoglossal to tongue muscles; accessory to trapezius/SCM).