Mesenteric lymph nodes

Nodi lymphoidei mesenterici superiores

Lymphatic & immuneLymphaticsAbdomen

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What it is

A hundred or more nodes strung along the branches of the superior mesenteric artery inside the fan-shaped mesentery that suspends the small intestine, densest along its root, which runs obliquely from the upper left to the lower right of the abdomen. Each node is a bean-shaped filter 5-15 mm long with a fibrous capsule, an outer cortex of B-cell follicles, a T-cell paracortex and an inner medulla. Several afferent lymphatics enter its convex surface; one or two efferents leave at the hilum.

Function

Filter lymph from the small intestine, including fat-laden chyle absorbed after a meal, and pass it to the intestinal trunk and cisterna chyli.

Size

100-150 nodes of 3-10 mm

Clinical note

Viral or Yersinia infection makes them swell and ache (mesenteric adenitis), the commonest mimic of appendicitis in children. They are a favoured site of lymphoma and of spread from bowel cancer.