Inferior vena cava
Inferior vena cava is one of the two major vein (the other being superior vena) of the systemic circulation, which bring blood from the body back to the heart. It conveys most of the blood from the body below the diaphragm.
The inferior vena cava is formed by the union of the common iliac veins behind the right common iliac artery. This union occurs at about the level of fifth lumbar vertebra.
After its origin, the inferior vena cava ascends to the right side of the aorta and pierces the central tendon of the diaphragm at the level of eighth thoracic vertebra. Finally, the vena cava drains into the right atrium.
Important structures related to the inferior vena cava include:
- Right sympathetic trunk: It lies behind the right margin of the inferior vena cava.
- Right ureter: It lies at a distance of about half inch from the right border of inferior vena cava.
- Entrance into lesser sac of peritoneal cavity: It separates the inferior vena cava from the portal vein.
Inferior vena cava is a major vein of body. Therefore, as per expectation, it has a large number of tributaries, including the following:
- Anterior visceral tributaries: These include the two hepatic veins.
- Lateral visceral tributaries: These include the right suprarenal vein, renal veins and right testicular or ovarian vein.
- Abdominal wall tributaries: These include the inferior phrenic vein and four lumbar veins.
- Veins of origin: These are the veins which unite to form the inferior vena cave. These are: Median sacral vein and left and right common iliac veins.
Remembering the tributaries of inferior vena cava seems difficult, however, if one keeps in mind that abdominal portion of the gastrointestinal tract is drained by portal vein, and that the left suprarenal and testicular (or ovarian) veins first drain into the left renal vein, then it becomes apparent that the tributaries of the inferior vena cava correspond to the branches of abdominal aorta.