Inferior vena cava system

The inferior vena cava (v. cava inferior) is the largest, has no valves, and is located retroperitoneally. It begins at the level of the intervertebral disc between the IV and V lumbar vertebrae from the confluence of the left and right common iliac veins on the right and slightly below the division of the aorta into the arteries of the same name. Initially, the inferior vena cava follows upward along the anterior surface of the right psoas major muscle. Situated to the right of the abdominal part of the aorta, the inferior vena cava passes behind the horizontal part of the duodenum, behind the head of the pancreas and the root of the mesentery. Then the vein lies in the groove of the same name in the liver, receiving the hepatic veins. Upon exiting the groove, it passes through its own opening in the tendinous center of the diaphragm into the posterior mediastinum of the thoracic cavity, penetrates into the pericardial cavity and, being covered by the epicardium, flows into the right atrium. In the abdominal cavity behind the inferior vena cava are the right sympathetic trunk, the initial sections of the right lumbar arteries and the right renal artery.

There are parietal and visceral tributaries of the inferior vena cava. Parietal tributaries are formed in the walls of the abdominal cavity and pelvic cavity. Visceral tributaries carry blood from the internal organs.

Parietal tributaries:

1. The lumbar veins (vv. lumbales, 3-4 in total) form in the walls of the abdominal cavity. Their course and the areas from which they collect blood correspond to the branches of the lumbar arteries. Often the first and second lumbar veins flow into the azygos vein, and not into the inferior vena cava. The lumbar veins of each side anastomose with each other using the right and left ascending lumbar veins. Blood flows into the lumbar veins from the vertebral venous plexuses through the spinal veins.
2. The inferior phrenic veins (vv. phrenicae inferiores), right and left, are adjacent in two to the arteries of the same name and flow into the inferior vena cava after it exits the groove of the liver of the same name.

Visceral tributaries:

1. The testicular (ovarian) vein (v. testicularis s. ovarica) is paired, begins at the posterior edge of the testicle (at the ovarian hilum) with numerous veins that encircle the artery of the same name, forming the pampiniform plexus (plexus pampiniformis). In men, the pampiniform plexus is part of the spermatic cord. Merging with each other, small veins form one venous trunk on each side. The right testicular (ovarian) vein flows at an acute angle into the inferior vena cava, slightly below the right renal vein. The left testicular (ovarian) vein flows at a right angle into the left renal vein.
2. The renal vein (v. renalis) is paired, runs from the renal hilum in a horizontal direction (in front of the renal artery). At the level of the intervertebral disc between the first and second lumbar vertebrae, the renal vein flows into the inferior vena cava. The left renal vein is longer than the right, runs in front of the aorta. Both veins anastomose with the lumbar veins, as well as with the right and left ascending lumbar veins.
3. The suprarenal vein (v. suprarenalis) emerges from the hilum of the adrenal gland. It is a short valveless vessel. The left adrenal vein flows into the left renal vein, and the right into the inferior vena cava. Some of the superficial adrenal veins flow into the tributaries of the inferior vena cava (inferior phrenic, lumbar, renal veins), and others flow into the tributaries of the portal vein (into the pancreatic, splenic, gastric veins).
4. The hepatic veins (vv. hepaticae, 3-4 in total) are short and located in the liver parenchyma (their valves are not always expressed). They flow into the inferior vena cava where it lies in the liver groove. One of the hepatic veins (usually the right one) is connected to the venous ligament of the liver - an overgrown venous duct that functions in the fetus - before flowing into the inferior vena cava.