Celiac Trunk

This is the first major branch arising from the abdominal aorta. It is located between the twelfth thoracic and first lumbar vertebral disk space. It gives rise to three major branches: the left gastric, hepatic, and splenic arteries. These three arteries are responsible for providing the blood supply to the organ systems in the superior portion of the abdomen, the liver, spleen, stomach, and pancreas.

In order of their origin the left gastric artery is the first to branch from the celiac trunk. This vessel runs along the lesser curvature of the stomach to supply the fundus and the gastroesophageal junction. It courses back toward the aorta and finally joins with the right gastric artery, which is a branch of the common hepatic artery.

The celiac trunk then bifurcates into two vessels, the common hepatic and the splenic arteries. The splenic artery is considered to be the largest branch of the celiac trunk. As its name implies, it runs toward the spleen, providing a supply of blood to various organs along the way. It is a tortuous vessel that gives off several branches including the pancreatic vessels, left gastroepiploic artery, short gastric arteries, and finally the splenic branches at its terminus.

The first branch of the common hepatic artery is the gastroduodenal artery. This vessel gives off the superior pancreaticoduodenal artery, which supplies the head of the pancreas with blood. Another branch continues as the right gastric epiploic artery to join with the left gastric epiploic artery. The common hepatic artery also gives rise to the right gastric artery, which runs toward the lesser curvature of the stomach and joins with the left gastric artery. At this point the hepatic artery is referred to as the hepatic artery proper. It courses upward to the liver and divides into the left and right hepatic arteries. The right hepatic artery usually gives off the cystic artery, which supplies the gallbladder with blood. The right and left hepatic arteries give off many branches and run in close proximity with branches from the hepatic portal vein. They empty into the hepatic sinusoids, which carry the blood to the central veins and out of the liver. Table 14-1 summarizes the various branches of the celiac trunk and the organ systems that are supplied by these vessels.

Superior Mesenteric Artery

The superior mesenteric artery (Fig. 14-3) arises from the aorta approximately 1.5 cm below the celiac trunk. It lies at about the level of the first and second lumbar intervertebral space. It is responsible for providing the blood supply for the viscera from the middle portion of the duodenum to the transverse colon.

The first major branch of the superior mesenteric artery is the inferior pancreaticoduodenal. It generally travels caudally, giving off approximately 10 to 14 branches to the small intestine. These intestinal arteries are referred to as the jejunal and ileal arteries. These branches usually join with branches above and below to form arches. As the arches approach the intestine they get smaller and smaller, finally giving rise to small straight vessels called the vasa recta that run to both sides of the small intestine.

The middle colic artery also arises in the same vicinity as the inferior pancreaticoduodenal artery. This artery divides into a right and left branch. The right branch of the middle colic artery joins with the right colic artery, and the left branch joins with the left colic branch of the inferior mesenteric artery. These form the marginal artery, which runs along the mesenteric border of the colon.

The right colic artery is the next vessel to arise from the superior mesenteric artery. It runs toward the ascending colon where it divides into an ascending and descending branch. There is an anastomosis between the descending branch of the right colic artery and the ascending branch of the ileocolic artery. The ascending branch of the right colic artery joins with the middle colic artery.

The ileocolic branch of the superior mesenteric artery is the most inferior of the major branches. It courses toward the cecum and gives off an ascending branch, which joins with the descending branch of the right colic artery. The ileocolic branch terminates at the level of the ileocecal junction and divides into a number of smaller branches (Table 14-2). One of these branches, the appendicular artery, supplies the appendix with blood.

Inferior Mesenteric Artery

The third major branch arising from the abdominal aorta is the inferior mesenteric artery (see Fig. 14-3). This vessel also provides a portion of the blood supply to the gastrointestinal system from the midtransverse colon to the rectum. It can be found on the ventral surface of the aorta at about the level of the third lumbar vertebra. The main trunk is longer than the superior mesenteric and is usually about 3 to 5 cm in length before it divides. The major branches from the vessel are the left colic artery, sigmoid arteries, and the superior rectal (hemorrhoidal) artery.

The left colic artery divides into an ascending and a descending branch. The ascending branch joins with the left branch of the middle colic artery and services the upper portion of the descending colon and a portion of the transverse colon. The descending branch supplies the midportion of the descending colon. It joins with the ascending branch of the sigmoid artery to supply the lower portion of the descending and sigmoid portions of the colon. There are usually two to three sigmoid arteries which give off both ascending and descending branches that form arcades or loops from which vasa recta are given off to supply the sigmoid colon with blood.

The inferior mesenteric artery continues into the superior rectal (hemorrhoidal) arteries, which divide to form middle and inferior rectal branches. These vessels supply the rectum and the anal canal. Table 14-3 summarizes the vasculature of the inferior mesenteric artery.

Venous Circulation

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