Which nerves are primarily involved in parasympathetic regulation of the GI tract?

• A. Vagus nerve and pelvic splanchnic nerves
• B. Hypoglossal nerve
• C. Phrenic nerve
• D. Spinal accessory nerve

Answer: (A)

Parasympathetic control of the GI tract comes mainly from two sources: the vagus nerve and the pelvic splanchnic nerves. The vagus carries preganglionic fibers to much of the gut (foregut and midgut), promoting peristalsis and secretions. The pelvic splanchnic nerves (S2–S4) provide parasympathetic input to the hindgut and pelvic organs, supporting continued bowel movements and secretions in that region.

Other nerves listed aren’t involved in GI parasympathetic regulation: the hypoglossal nerve controls tongue muscles; the phrenic nerve supplies the diaphragm; and the spinal accessory nerve supplies neck and shoulder muscles.