Which cranial nerve provides parasympathetic innervation to thoracic and abdominal organs?

• A. Facial nerve
• B. Vagus nerve
• C. Trigeminal nerve
• D. Glossopharyngeal nerve

Answer: (B)

The vagus nerve carries parasympathetic fibers that reach the thoracic and much of the abdominal organs. Its preganglionic fibers travel from the brainstem, descend into the thorax, and then into the abdomen, forming networks like the esophageal plexus and the anterior and posterior vagal trunks. These fibers innervate the heart, lungs, and most of the foregut and midgut organs (stomach, liver, pancreas, and much of the intestines up to the proximal two-thirds of the transverse colon), helping regulate heart rate, bronchoconstriction, digestion, and glandular secretions.

The other nerves have different roles: the facial nerve mainly supplies parasympathetic input to lacrimal and certain salivary glands in the head; the glossopharyngeal nerve targets the parotid gland; and the trigeminal nerve is primarily sensory and motor for the face without parasympathetic innervation to thoracic or abdominal organs.