V. cava inferior, inferior vena cava, is the thickest venous trunk in the body, lies in the abdominal cavity near the aorta, to the right of it. It is formed at the level of the IV lumbar vertebra from the confluence of two common iliac veins. slightly below the aortic division and immediately to the right of it. The inferior vena cava is directed upwards and somewhat to the right, and the more it moves away from the aorta. The lower section adjoins the medial edge of the right m. psoas, then goes to the front of its surface and at the top lies on the lumbar part of the diaphragm. Then, lying in the sulcus venae cavae on the posterior surface of the liver, the inferior vena cava passes through the foramen venae cavae of the diaphragm into the chest cavity and immediately flows into the right atrium. Tributaries flowing directly into the inferior vena cava correspond to the paired branches of the aorta (except for vv. He paticae). They are divided into the wall veins and internal veins. Parietal veins flowing into the inferior vena cava:
1) vv. lumbales dextrae et sinistrae, four on each side, correspond to the arteries of the same name, take anastomoses from the vertebral plexuses; they are interconnected by longitudinal trunks, vv. lumbales ascendentes;
2) vv. phrenicae inferiores flow into the inferior vena cava where it passes in the groove of the liver.
The veins of the viscera flowing into the inferior vena cava:
1) vv. testiculares in men (vv. ovaricae in women) begin in the area of the testicles and braid like arteries in the form of a plexus (plexus pampiniformis); right v. testicularis flows directly into the inferior vena cava at an acute angle, the left – into the left renal vein at a right angle. This latter circumstance makes it difficult, perhaps, the outflow of blood and causes a more frequent appearance of varicose veins of the left spermatic cord in comparison with the right one (in a woman, v. Ovarica begins at the gate of the ovary);
2) vv. renales, renal veins, go in front of the arteries of the same name, almost completely covering them; the left is longer than the right and passes in front of the aorta;
3) v. suprarenalis dextra infuses into the inferior vena cava immediately above the renal vein; v. suprarenalis sinistra usually does not reach the vena cava and merges into the renal vein in front of the aorta;
4) vv. hepaticae, the hepatic veins, flow into the inferior vena cava where it passes along the posterior surface of the liver; hepatic veins carry blood from the liver, where blood flows through the portal vein and the hepatic artery.