The inferior vena cava is valveless and is formed in the abdomen by the union of the right and left common iliac arteries, anterior to the fifth lumbar vertebral body.  It ascends to the right of the abdominal aorta, anterior to the lumbar and lower thoracic vertebrae.  On reaching the liver it passes in a deep groove on the posterior surface of the liver to pierce the tendinous part of the diaphragm at the level of the eighth thoracic vertebra with the phrenic nerve.  It passes through the fibrous pericardium to end in the postero-inferior part of the right atrium.  Anteriorly at its origin it is overlapped by the right common iliac artery, posteriorly are the lower three lumbar vertebral bodies and intervening intervertebral discs, the anterior longitudinal ligament, right psoas major, right sympathetic trunk, third and fourth lumbar arteries, right crus of the diaphragm and medial part of the right adrenal gland.  It receives the lumbar, right gonadal and suprarenal, inferior phrenic, renal and hepatic veins.