4. Remove the peritoneum from the right side of the mesentery to expose and identify the superior mesenteric artery and vein and their branches.

Dissection Intestinal Vessels The blood supply to the small intestine is found in its mesentery. In order to expose these vessels it is necessary to remove one side of the mesenteric attachment. Reflecting the intestine to the left, lower quadrant exposes the right side of the mesenteric attachment. This may be peeled off using blunt dissection, forceps works well to expose the underlying blood vessels which lie between the layers of peritoneum. Having exposed the vessels, now identify them. First of all, the superior mesenteric artery to the left and posterior and the vein, right and anterior. They give off intestinal branches to the intestine itself, some 17. The terminal end of the superior mesenteric artery loops downward and to the right to end near the cecum at the ileocecal junction. The next branch is the ileocolic artery, a large artery which goes towards the ileocecal junction named by its distribution to the colon and the ileum. In anastomosis, was its distal end of the superior mesenteric artery. The ascending colon is supplied by the right colic artery. In this particular cadaver, it is a branch of the ileocolic. It may also be a branch directly off the superior mesenteric artery and its course will be across as shown. The blood supply to the transverse colon is the middle colic artery off the superior mesenteric. It is found in the transverse mesocolon. The branches of the middle colic artery anastomose with the branches of the ileocolic and right colic artery to form an anastomotic channel along the margin of the large bowel called the marginal artery. Turn your attention to the intestinal branches and their actual distribution to the intestine. The intestinal branches are large proximally. They give rise to large arch-like anastomoses between the individual branches which are called arcades. These give rise to straight vasa recta which supply the intestine itself. The arcades are less numerous and larger proximally and more numerous and complex distally on the small intestine. In this close up view notice the arterial arcades and the anastomotic channels between the vessels which give rise to the vasa recta.