Mesenteric Arteries (MESENTERICAE ARTERIAE,)

MESENTERICAE ARTERIAE, VENAE. A distinction is made between the superior and inferior mesenteric arteries. The superior mesenteric artery, a. mesent. sup., is unpaired and is a branch of the abdominal aorta (sometimes the fourth branch of the celiac artery) (see Vol. X, pp. 213-214, Fig. 20); it arises from the anterior surface

Figure 1. 1-superior mesenteric artery; 2-uncinate process of the pancreas; 3-inferior pancreaticoduodenal artery; 4-intestinal branches; 5-middle colic artery; 6-ileocolic artery; 7-gastroduodenal artery; 8-right gastroepiploic artery; 9-inferior mesenteric artery; 10-left colic artery; 11-sigmoid artery; 12-superior hemorrhoidal artery.

of the aorta at the level of L1, slightly below the celiac artery (see Vol. IV, Table II, Fig. 3, pp. 147-148, and Vol. X, Figs. 2-3, pp. 203-204), and descends behind the head of the pancreas. In the region of the pancreatic notch, it emerges to the surface, lies in front of the uncinate process of the pancreas (see Pancreas) and the inferior, or ascending, part of the duodenum (Fig. 1), and continues further downward, lying between the layers of the peritoneum in the thickness of the mesentery and forming a small arc with its convexity facing left and forward (Fig. 2). Along its path, the artery gives off the following branches (Fig. 1): 1. Inferior pancreaticoduodenal artery; it arises from the right side of the trunk of the superior mesenteric artery, in front of the uncinate process, and runs to the left along the convexity of the inferior part of the duodenum, between it and the pancreas. It nourishes the wall of the duodenum and the pancreas along the way. Above, it anastomoses with the superior artery of the same name. 2. Intestinal arteries, intestinal branches. In a variable number (from 10 to 20 or more), they arise to the left from the trunk of the superior mesenteric artery, lie in the thickness of the mesentery, and nourish the wall of the jejunum (jejunal branches) and the ileum (ileal branches) (Fig. 2). Along their path, the intestinal arteries branch in a tree-like fashion and form a network of anastomoses arranged in a series of arcs called arcades. A distinction is made between arcs of the 1st, 2nd, 3rd order, etc. The number of arcs, as well as the number of their rows, is very variable (usually there are 2-5 rows of anastomotic arcs). From each arc, branches extend to the mesentery, and the arcs of the last order give off numerous branches to the walls of the intestines. The rightmost ileal artery connects with the ileocecal-colic-appendicular artery. 3. Ileocecal-colic-appendicular artery (abbreviated as ileocolic artery); it arises from the right side of the trunk of the superior mesenteric artery and descends downward behind the peritoneum to the ileocecal angle, breaking up into the following branches: a) terminal ileal artery, running to the terminal section of the ileum; b) cecal artery, supplying the cecum and branching mainly in the posterior and left sections of the cecum; c) right colic artery, a branch to the ascending colon; it runs from the ileocecal angle from bottom to top along the inner edge of the ascending colon; d) appendicular artery; it is usually a branch of the terminal ileal artery and descends downward, behind the terminal section of the ileum, to the mesentery of the vermiform appendix, where it gives off 3-7 branches nourishing the wall of the latter; very of

Figure 2. 1-superior mesenteric artery; 2-superior mesenteric vein; 3-jejunal intestinal arteries; 4-ileal arteries; 5-ileocecal-colic-appendicular artery; 6-right colic artery; 7-middle colic artery; 8-ascending colon; 9-duodenum; 10-transverse colon; 11-cecum; 12-ileum; 13-sigmoid colon.