The roots of the portal vein anastomose with the roots of the veins belonging to the systems of the upper and lower hollow veins, forming the so-called portocaval anastomoses, which have practical significance. If we compare the abdominal cavity with a cube, then these anastomoses will be located on all its sides, namely:
1. Upstairs, in the esophagus pars abdominalis, between the roots v. gastricae sinistrae, which flows into the portal vein, and vv. esophageae flowing into vv. azygos et hemyazygos and further in v. cava superior.
2. Down in the lower part of the rectum, between v. rectalis superior, flowing through v. mesenteria inferior to the portal vein, and vv. rectales media (tributary v. iliaca interna) et inferior (tributary v. pudenda interna), flowing into v. iliaca interna, and further v. iliaca communis – from system v. cava inferior.
3. In front, in the navel, where their tributaries anastomose vv. paraumbilicales, going in the thickness lig. teres hepatis to portal vein, v. epigastrica superior from system v. cava superior (v. thoracica interna, v. brachiocephalica) and v. epigastrica inferior of system v. cava inferior (v. iliaca externa, v. iliaca communis). Portokavalny and caval caval anastomoses are obtained, having a meaning of a circulating pathway of blood outflow from the portal vein system in the event of obstructions in the liver (cirrhosis). In these cases, the veins around the navel expand and acquire a characteristic appearance (“the head of a jellyfish”).
4. Posteriorly, in the lumbar region, between the roots of the veins of the mesoperitoneal colon (from the portal vein system) and parietal vv. lumbales (from the system v. cava inferior).
5. In addition, there is a caval caval anastomosis between the roots vv on the posterior abdominal wall. lumbales (from the v. cava inferior system) that are associated with the v. lumbalis ascendens, which is the beginning of vv. azygos (right) et hemiazygos (left) (from the system v. cava superior).
6. Cavo-caval anastomosis between vv. lumbales and intervertebral veins, which in the neck are the roots of the superior vena cava.