Inferior vena cava. The inferior vena cava is also referred to as the posterior vena cava. The inferior vena cava is a large vein that carries de-oxygenated blood from the lower body to the heart. De-oxygenated blood means most of the oxygen has been removed by tissues, and therefore the blood is darker.he right atrium is located on the lower right back side of the heart. The inferior vena cava runs posterior, or behind, the abdominal cavity. This vein also runs alongside the right vertebral column of the spine. The inferior vena cava is the result of two major leg veins coming together.