The superior vena cava ends in the right atrium at the third costal cartilage. The inferior vena cava pierces the diaphragm at the level of the xiphisternal joint, and after a course of half an inch, enters the right atrium at the level of the sixth costal cartilage.
Surgical Anatomy. Arch Surg. 1997;132(6):604. doi:10.1001/archsurg.1997.01430300046009