what is the thoracic vena cava also called
A vein running along the back wall of the thorax on the right side of the thoracic aorta; at the level of the fourth thoracic vertebra, the azygos vein curves forward, over the top of the hilum (root) of the right lung, and empties its blood into the superior vena cava.he vein accompanying the common iliac artery; it is formed by the union of the external and internal iliac veins, and it ends by merging with the opposite common iliac vein to form the inferior vena cava.