Final answer:
The vagus nerve (CN X) is responsible for keeping the uvula in the midline.
Step-by-step explanation:
The cranial nerve responsible for keeping the uvula in the midline is the vagus nerve (CN X). The vagus nerve plays a crucial role in controlling the muscles of the neck, throat, and oral cavity. It also contributes to the regulation of organs in the thoracic and upper abdominal cavities, including pupillary constriction and salivation.