The superior vena cava ends in the right atrium at the 3rd 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 6th costal cartilage.
1. Grant JCB. A Method of Anatomy: Descriptive and Deductive. 5th ed. Baltimore, Md: Williams & Wilkins Co; 1952:544.