Book 4 - Self Instructional Manual for Cancer Registrars - SEER ...

The blood supply to the wall of the large intestine is derived from branches of the superior andthe inferior mesenteric arteries. The superior mesenteric artery and its branches supply the right sideof the colon, hepatic flexure and just beyond the midline of the transverse. The inferior mesentericartery and its branches supply the left side of the colon and a portion of the left transverse. Theveins enter the inferior mesenteric vein and eventually the portal vein.The lymphatics of the large intestine drain primarily into the superior and inferior mesentericlymph nodes before eventually reaching the cisterna chyli and thoracic duct. To refresh your memory,turn to page 58 of the lymphatic system.Epicolic lymph nodules lying beneath the serosa and paracolic lymph nodes in the adjacentmesentery are found along the length of the colon. Lymph collected in the paracolic nodes drainsthrough the lymphatic vessels and intercalating lymph nodes in the mesentery toward the branchingof the superior and inferior mesenteric arteries from the aorta.Perirectal lymph nodes drain, in addition, to nodes along branches of the internal iliac artery andto sacral promontory nodes.The branches of the major arteries and lymphatics are:Superior MesentericInferior Mesentericileocolicleft colicright colic hemorrhoidal, superiormid-colicsigmoidal (sigmoid mesenteric)cecal, anterior/posteriorInternalIliac (Hypogastric)sacral (lateral sacral)hemorrhoidal, middleOften lymph nodes whose configurations have been obliterated by tumor are described by thepathologist as tumor nodules in pericolic fat. These are not to be confused with Peyer's patcheswhich are areas of lymphoid tissue in the mucosa.221