Hepatic Portal System (Advanced) USMLE, Limited Edition > Gross Anatomy > Gross Anatomy

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Hepatic portal system

• A special circulation system that transports venous blood from the digestive organs to the liver.

• Transports blood from the stomach, spleen, pancreas, and small and large intestines to the liver. This distinct circulatory pathway exists to allow the liver to metabolize nutrients and toxins from blood that leaves the digestive organs.

Primary tributaries of the hepatic portal vein:

Superior mesenteric vein Drains tissues of the right side of the abdomen.

- Ileocolic vein drains blood from the distal small intestine and the proximal large intestine

- Right colic vein courses from the right side of the abdomen to drain blood from the large intestine

- Middle colic vein drains blood from the large intestine.

- Intestinal veins drain the jejunum and ileum of the small intestine. These drain into the left side of the superior mesenteric vein.

- Pancreatic and duodenal veins

- Right gastro-omental vein, which runs along the inferior border of the stomach (aka, greater curvature), drains into the superior mesenteric vein.

• The "omental" portion of the gastro-omental name is derived from the greater "omentum," the apron-like fold of peritoneum that drapes over the intestines anteriorly.

Splenic vein Drains structures on the left side of the abdomen.

- Merges with superior mesenteric vein to form hepatic portal vein

- Short gastric veins from stomach

- Left gastro-omental vein, which courses along the inferior border of the stomach and meets the right gastro-omental vein.

- Pancreatic veins

- Inferior mesenteric vein

Inferior mesenteric vein

1 / 2 Drains tissues of the lower left side of the abdomen into the splenic vein.

- Superior rectal vein

- Multiple sigmoid veins, which drain the sigmoid colon

- Left colic vein, which drains the descending and transverse colon segments.

Additional information:

• Hepatic vein

- Drains blood from liver to inferior vena cava

- Helps secure liver in place

• Smaller tributaries of the hepatic portal vein:

- Cystic veins from gallbladder

- Left and right gastric veins from stomach

Clinical Correlations:

• Portal hypertension occurs when the hepatic portal vein becomes blocked.

• Blood clots can cause obstruction of the hepatic portal vein, but, more commonly, portal hypertension is the result of cirrhosis, in which the liver tissue is replaced by scar tissue in response to damage from a variety of causes, including chronic alcohol intoxication or hepatitis C.

• As blood flow is obstructed, blood pressure in the hepatic portal system increases, and venous engorgement occurs. These enlarged veins form thin-walled varices, which are susceptible to trauma.

• Rupture of esophageal varices, which form at the junction of the stomach and esophagus, can cause fatal gastrointestinal hemorrhage.

Review veins of the trunk.