Portal vein - tributaries, portocaval (portosystemic) anastomosis

Portal vein carries nutrient rich blood from stomach, intestines, pancreas and spleen to the liver. This is formed from the anastomosis of splenic vein and superior mesenteric vein at L2 level. As the portal vein enters the liver, it splits into left and right branches entering the liver parenchyma.

Portal vein - tributaries

It’s main tributaries include:

• Superior mesenteric vein
• Splenic vein
• inferior mesenteric vein (can also drain into superior mesenteric vein)

Additional veins that can drain directly into the portal vein after the union of the main venous branches

• Cystic vein
• Paraumbilical vein
• Left and right gastric vein
• Superior posterior pancreaticoduodenal vein

After entering the hepatoduodenal ligament, it runs retroperitoneally behind pancreas and duodenum, which allows the portal vein to divide into left and right branches.

Branches of splenic vein

• Small gastric vein
• Left gastroomental vein
• Posterior gastric vein
• Pancreatic vein

Branches of superior mesenteric vein

• Right gastroomental vein
• Pancreaticoduodenal vein
• Pancreatic Vein
• Jejunal vein
• Ileal vein
• Ileocolic vein
• right and medial colic vein

Branches of inferior mesenteric vein

• Left colic vein
• sigmoid ein
• superior rectal vein

Portocaval anastomosis

The portocaval anastomosis are connecting the systematic (superior and inferior vena cava) and portal venous system, which allows alternative routes for circulating venous blood to pass through, when a blockage in one of the veins occurred. This also ensures that blood from gastrointestinal system can reach the heart without going through the liver in case of any liver problems.

1. v. portae → vv. gastricae (v. gastrica sin.) → oesophageal venous plexus → vv. oesophageales →v. azygos + hemiazygos → v. cava sup.
2. v. portae → v. splenica → v. mesenterica inferior → v. rectalis superior → adventitia of rectum and its venous plexus (plexus venosus rectalis externus) + submucosa of rectum (plexus venosus rectalis externus = plexus haemorrhoidalis) → a) v. rectalis media → v. iliaca interna → v. iliaca communis → v. cava inf. /// b) v. rectalis inferior → v. pudenda interna → v. iliaca interna → v. iliaca communis → v. cava inf.
3. v. portae → vv. paraumbilicales (inside of lig. teres hepatis) → a) v. epigastrica superior → vv. thoracica interna → v. subclavia → v. brachiocephalica → v. cava sup. /// b) v. epigastrica inferior → v. iliaca externa → v. iliaca communis → v. cava inf.
4. v. portae → v. mesenterica sup. + v. splenica → small všine inside of mesenteries and peritoneal folds = Retzius‘s clutches → retroperitoneal veins → tributaries for v. suprarenales sin., v. renalis sin., vv. lumbales, vv. lumbales ascendentes → v. cava sup. + v. cava inf.
5. v. portae → veins of capsula fibrosa hepatis (in region of area nuda) → veins of diaphragm → vv. phrenicae superiores, vv. pericardiacophrenicae, vv. musculophrenicae, vv. intercostales posteriores → v. cava sup. / vv. phrenicae inferiores → v. cava inf.
6. v. portae → ductus venosus reapertus → vv. hepaticae → v. cava inf.

Bibiography

Sobotta, Anatomy Textbook. Jens Waschke et al. English Edition with Latin Nomenclature. ISBN 978-0-7020-6760-0

Rozgoňová, B. (n.d.) Portocaval Anastomoses, Second faculty of Medicine Charles University Department of Anaromy, Portocaval anastomoses. Available at: https://anatomie.lf2.cuni.cz/sites/anatomie/files/page/files/2017/portocaval_anastomoses_2_ap2.pdf