superior vena cava
Diagram of the human heart. The superior vena cava, inferior vena cava, and pulmonary vein are the large veins that empty into the heart; the aorta and pulmonary artery are large arteries that lead out of the heart.
The superior vena cava starts at the top of the chest, behind the lower edge of the right first rib and close to the sternum (breastbone). It travels some 7.5 cm downward, passing through the pericardium (outer lining of the heart) before connecting to the right atrium.
The superior vena cava is formed by the junction of the right and left brachiocephalic (innominate) veins, which themselves are formed from the union of the subclavian veins (draining venous blood from the arms), the jugular veins (draining blood from the head and neck), and several minor veins. The superior vena cava also receives blood from the azygos vein, which drains much of the chest.