Which components comprise the enteric nervous system that regulate GI motility and secretion?

• A. Meissner and Auerbach plexuses
• B. Vagus nerve and sympathetic trunk
• C. Spinal cord segments
• D. Somatic nerves

Answer: (A)

Two neural networks reside within the wall of the GI tract that form the enteric nervous system and regulate function: the myenteric (Auerbach) plexus and the submucosal (Meissner) plexus. The myenteric plexus sits between the circular and longitudinal muscle layers and primarily coordinates GI motility, guiding peristaltic and mixing contractions. The submucosal plexus lies in the submucosa and mainly controls secretions, local blood flow, and absorption, adjusting the environment inside the lumen. Together, they enable intrinsic regulation of GI activity, with additional modulation coming from extrinsic autonomic inputs like the vagus nerve and sympathetic nerves. The other neural components listed—extrinsic nerves and spinal/somatic pathways—do not comprise the enteric nervous system itself.