vagus nerve /vā″gəs/ [L, vagus, wandering, nervus, nerve] , either of the longest pair of cranial nerves mainly responsible for parasympathetic control over the heart and many other internal organs, including thoracic and abdominal viscera. The vagus nerves communicate through 13 main branches, connecting to four areas in the brain. Also called nervus vagus, pneumogastric nerve, tenth cranial nerve.
