Abdominal Veins and Arteries

Veins usually carry blood straight to the atria of the heart, but those of the abdominal tissues are exceptions. These come from networks in the stomach, intestines, pancreas, and spleen, and carry blood from these organs through a "portal vein" to the liver. There, the blood enters capillarylike "hepatic sinusoids," called the "hepatic portal system." The tributaries of the portal vein include (1) the right and left "gastric veins" from the stomach; (2) the "superior mesenteric vein" from the small intestine, ascending colon, and transverse colon, and (3) the "splenic vein" from a number of merging veins from the spleen, pancreas, and part of the stomach. Its largest tributary is the "inferior mesenteric vein," which brings blood up from the descending colon, sigmoid colon, and the rectum. After passing through the portal veins of the liver, blood is carried through a series of merging vessels into the "hepatic veins." These empty into the "inferior vena cava," and return the blood into circulation. The corresponding arteries of the same names are taking oxygenated blood to these sites in paths parallel to those of the veins.