The Superior Vena Cava (SVC) is the large vein which takes blood that has been deoxygenated (already used up and needs to be oxygenated by the lungs) from the upper part of the body to the heart. It connects to the right atrium of the heart. From there, the blood goes through the pulmonary artery and into the lungs to be oxygenated. The Vena Cava is the largest vein in the body. Part of it is the SVC and the other part is the Inferior Vena Cava (IVC).
The superior vena cava is a large vein that returns blood to the heart from the head, neck, and arms. The inferior vena cava is the large vein that returns blood from the lower half of the body.
The vena cava is the main vein in the body which returns blood to the heart from the systemic vasculature. It opens into the right atrium which pumps it to the right ventricle and from there it is pumped into the lungs. The vena cava can be broken down into 2 portions: Superior and inferior. The inferior portion generally collects the blood from below the heart and the superior portion drains the blood from above the heart (ie arms, head). The superior portion also receives lymph from the thoracic duct.