Superior mesenteric plexus

Superior mesenteric plexus is a downward continuation of the celiac prevertebral plexus and refers to a meshwork of neurons which is situated near the root of superior mesenteric artery and posterior to the pancreas. Various secondary plexuses arise here, which follow the course of arterial branches of superior mesenteric artery. These include plexuses around jejunal and ileal arteries, and the arterial branches to the colon in the hind gut, such as ileocolic, right and middle colic arteries.

The superior mesenteric plexus contains parasympathetic motor neurons from the vagus nerve and sympathetic motor neurons which arrive via the splanchnic nerves. In addition, visceral afferent neurons also exist inside the superior mesenteric plexus, which transmit the visceral sensory information to the central nervous system via the vagus nerve and the sympathetic splanchnic nerves.

An important ganglion, called the superior mesenteric ganglion, is situated within the superior mesenteric plexus, close to the root of the superior mesenteric artery. The sympathetic preganglionic neurons arriving from the splanchnic nerves synapse with cell bodies of post-ganglionic sympathetic neurons inside this ganglion. The post-ganglionic sympathetic neurons then innervate the vessels and glands within the gastrointestinal tract, causing vasoconstriction and reducing secretions.