The inferior vena cava conveys most of the blood from the body below the diaphragm to the right atrium of the heart. It is formed by the union of the common iliac veins behind the right common iliac artery at the level of the 5th lumbar vertebra. It ascends on the right side of the aorta, pierces the central tendon of the diaphragm at the level of the 8th thoracic vertebra, and drains into the right atrium of the heart.
The right sympathetic trunk lies behind its right margin and the right ureter lies close to its right border. The entrance into the lesser sac separates the inferior vena cava from the portal vein.