Final answer:
The vagus nerve is the cranial nerve responsible for the majority of visceral innervation, regulating functions such as heart rate, digestion, and breathing.
Step-by-step explanation:
The cranial nerve responsible for the majority of visceral innervation is the vagus nerve. The vagus nerve, also known as cranial nerve X, is responsible for the autonomic control of organs in the thoracic and upper abdominal cavities. It plays a crucial role in regulating functions such as heart rate, digestion, and breathing.