Final answer:
The vagus nerve, also known as cranial nerve X, is responsible for autonomic control of organs in the thoracic and upper abdominal cavities.
Step-by-step explanation:
The vagus nerve, also known as cranial nerve X, is responsible for autonomic control of organs in the thoracic and upper abdominal cavities. It is one of the twelve cranial nerves that serve the head and neck. The vagus nerve primarily targets autonomic ganglia in these regions, controlling functions such as pupillary size, salivary glands, and visceral activities.