Human Anatomy and Physiology - N. I. Fedyukovich 2003

Cardiovascular System
Veins of the Systemic Circulation
Portal Vein System

From the unpaired abdominal Organs, excluding the Liver, Blood is first collected into the PORTAL VEIN SYSTEM, through which it flows to The Liver and then, via the hepatic Veins, into the INFERIOR VENA CAVA.

The portal vein (Fig. 96) is a large visceral vein (5–6 cm in length, 11–18 mm in diameter) formed by the confluence of the inferior and superior mesenteric veins and the splenic vein. It receives tributaries from The Stomach, small and large intestines, Spleen, Pancreas, and Gallbladder. The portal vein then runs toward the porta hepatis and enters the liver parenchyma. Within the liver, the portal vein divides into right and left branches, each of which further subdivides into segmental and smaller branches. Inside the liver lobules, they branch into wide capillaries (sinusoids) and drain into central veins, which continue into sublobular veins. The latter unite to form three or four hepatic veins. Thus, blood from the digestive tract passes through the liver before finally entering the inferior vena cava system.

The superior mesenteric vein ascends within the ROOT of the mesentery of the Small Intestine. Its tributaries include the jejunal and ileal veins, pancreatic, pancreaticoduodenal, ileocolic, right gastro-omental, right and middle colic veins, and the appendicular vein. The superior mesenteric vein collects blood from all of the aforementioned organs.

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Fig. 96. The portal vein system:

1 — superior mesenteric vein; 2 — stomach; 3 — left gastro-omental vein; 4 — left gastric vein; 5 — spleen; 6 — tail of pancreas; 7 — splenic vein; 8 — inferior mesenteric vein; 9 — descending colon; 10 — rectum; 11 — inferior rectal vein; 12 — middle rectal vein; 13 — superior rectal vein; 14 — ileum; 15 — ascending colon; 16 — HEAD of pancreas; 17, 23 — right gastro-omental vein; 18 — portal vein; 19 — cystic vein; 20 — gallbladder; 21 — duodenum; 22 — liver; 24 — prepyloric vein

The splenic vein collects blood from the spleen, stomach, pancreas, duodenum, and greater omentum. Its tributaries include the short gastric veins, pancreatic veins, and the left gastro-omental vein.

The inferior mesenteric vein is formed by the union of the superior rectal vein, left colic vein, and sigmoid veins; it collects blood from the walls of the upper rectum, sigmoid colon, and descending colon.



Last update: 08/08/2026

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