Mesenteric (pre-aortic) lymph nodes

Lymph from the gastrointestinal tract follows its arteries back to the aorta. The superior mesenteric nodes of the small-bowel mesentery (≈ 100–150 nodes) are arranged in tiers: juxta-intestinal nodes near the gut wall, intermediate nodes along the jejunal and ileal arterial arcades, and central nodes at the root of the superior mesenteric artery. The colon has an analogous sequence — epicolic (on the wall), paracolic (along the marginal artery), intermediate (along the colic arteries) and principal nodes at the origins of the superior and inferior mesenteric arteries.

These ultimately drain to the three pre-aortic groups, following the embryological gut territories: coeliac nodes (foregut — stomach, duodenum to the major papilla, liver, gallbladder, pancreas, spleen), superior mesenteric nodes (midgut — to the distal third of the transverse colon) and inferior mesenteric nodes (hindgut — to the upper anal canal). Their efferents form the intestinal trunk, which enters the cisterna chyli. The mesenteric nodes therefore see enormous amounts of food and microbial antigen and, after meals, milky chyle.