Final answer:
Parasympathetic preganglionic fibers in the vagus nerve synapse at terminal ganglia in the thoracic and abdominal cavities, especially those associated with the dorsal nucleus of the vagus nerve and nucleus ambiguus.
Step-by-step explanation:
Unlike parasympathetic preganglionic fibers that run in other cranial nerves, those in the vagus nerve synapse at terminal ganglia located in the thoracic and abdominal cavities. Specifically, neurons in the dorsal nucleus of the vagus nerve and the nucleus ambiguus project through the vagus nerve (cranial nerve X) to the terminal ganglia which are often incorporated into the structure of the organ. These include the mesenteric plexus of the digestive tract organs and the intramural ganglia. Parasympathetic output is critical for rest-and-digest functions, regulating organs such as the heart, bronchi, and esophagus in the thoracic cavity, and the stomach, liver, pancreas, gall bladder, and small intestine in the abdominal cavity.