During a right hemicolectomy, inadvertent damage to the superior mesenteric plexus disrupts sympathetic innervation. Which visceral response is specifically expected?

• A Increased peristalsis and secretion in the small intestine and right colon
• B Decreased peristalsis and secretion in the small intestine and right colon
• C Loss of pain sensation from the small intestine
• D Both A and C ✓

Explanation

Sympathetic supply to the small intestine and right colon (via greater and lesser splanchnic nerves → coeliac and superior mesenteric ganglia → superior mesenteric plexus) inhibits peristalsis and secretion (via alpha-2 and alpha-1 receptors). Loss of sympathetic input therefore disinhibits the gut causing increased motility and secretion. Critically, visceral afferents (pain fibres) from the small intestine and right colon also travel with the sympathetic fibres through the superior mesenteric plexus back to the T5–T10 spinal cord — so damage also abolishes visceral pain from these segments.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.