Upper Vena cava, also called the Superior vena cava is a vein that is a short but large (carries a large amount of blood) vein that carries deoxygenated blood to the heart from the upper half of the body and gives this blood to the heart at the right atrium. . The right and left brachiocephalic veins which receive blood from the head, neck and the hands or upper limbs merge together to form the superior vena cave. Just before entering the right atrium, the azygous vein that carries blood from the rib area also merges with the superior vena cava. So the main function of the vein is to carry deoxygenated blood from the upper parts to the heart so that it is pumped for oxygenation to the lungs.