The portal vein collects blood from the abdominal organs and transports it to the liver. It forms from the union of the superior mesenteric vein and splenic vein. It branches within the liver into left and right portal veins which supply the left and right sides of the liver through hepatic sinusoids before draining into the hepatic veins and inferior vena cava.

1. Portal vein
Dr Sunil Thomas George

2. Introduction
 The portal system includes all veins that carry blood from the abdominal part of the alimentary
tract, the spleen, pancreas and gallbladder.

3. Development
 Portal vein develops from the following sources:
1. Infraduodenal part -from a part of the left vitelline vein distal to the dorsal
anastomosis.
2. Retroduodenal part –from the dorsal anastomosis between the two vitelline veins.
3. Supraduodenal part –from the cranial part of the right vitelline vein.

4.  The portal vein is approximately 7.5 cm in length
 Portal pressure is about 7mmHg
 Portal blood flow in man is about 1000–1200ml/min
 Crossing-over of the bloodstream can occur in the portal vein.
 Portal venous blood derived from the mesenteric venous circulation
constitutes approximately 75% of total hepatic blood flow

5.  Formed by the union of the superior mesenteric vein and the splenic vein
 Inferior mesenteric vein, enters its medial third. Occasionally, the junction of the superior
mesenteric and splenic veins.
 Superior mesenteric vein is formed by tributaries from the small intestine, colon and head of the
pancreas, and irregularly from the stomach
posterior to the head of the pancreas at about the level of the second lumbar vertebra.
blood from the left part of the colon and rectum,
via the right gastroepiploic vein.

6.  Splenic veins (5–15 channels) originate at the splenic hilum join near the tail of the pancreas with
the short gastric vessels to form the main splenic vein.
tributaries from the head of the pancreas, and the left gastro-epiploic vein enters it near the spleen.

7.  Enters the hilum of the liver, the portal vein divides into the left and right portal
vein branches, which supply the left and right sides of the liver,
 The umbilical vein drains into the left portal vein,
 The cystic vein from the gallbladder drains into the right portal vein.
 Portal vein–derived and hepatic artery–derived blood flow converge in high
compliance, specialized vascular channels termed hepatic sinusoids
 Portal venules drain into hepatic sinusoids that, in turn, are drained by the hepatic
veins into the inferior vena cava.

8. Summary
 Portal vein is a large vein which collects blood from:
1. Abdominal part of alimentary tract
2. Gall bladder
3. Pancreas
4. Spleen
 Conveys to liver, breaks up into sinosoids

9. Summary
 Tributaries:
1. Splenic
2. Superior mesenteric
3. Left gastric
4. Right gastric
5. Superior pancreaticoduodenal
6. Cystic
7. Paraumblical veins