Nerves of the thoracic and abdominal regions. The autonomic nervous system (ANS), a division of the peripheral nervous system (PNS), is the system of motor neurons that innervate smooth and cardiac muscle and glands. The vagus nerves, within the ANS, provide fibers to the neck and contribute to nerve plexuses that serve the organs of the thoracic and abdominal cavities. The cardiac nerve plexus supplies fibers to the heart that slow heart rate as needed. The esophageal plexus supplies the esophagus, which innervate the stomach. ANS plexuses also contribute to fibers of the large intestine and mesentery.