Superior vena cava

The superior vena cava (SVC, Latin: vena cava superior) is a short, large-diameter vein of the thorax that is located vertically and drains into the right atrium of the heart.

Most of the SVC lies on the anterior and right side of the superior mediastinum. However, the lower half of the SVC is covered by the pericardium and is therefore contained within the middle mediastinum. 

The SVC begins by the merging of the right and left brachiocephalic veins. The fusion happens posterior to the lower edge of the 1st right costal cartilage. The SVC descends vertically and ends at the lower edge of the right 3rd costal cartilage, where it drains into the right atrium.

Immediately before entering the pericardial sac (at the level of the 2nd costal cartilage), it receives the azygos vein and may also receive pericardial and mediastinal veins.

The SVC is one of the two large veins by which deoxygenated blood is returned from the body to the right side of the heart. The SVC drains everything above the diaphragm, while the inferior vena cava (IVC) drains the lower body below the diaphragm.