do the superior and inferior vena cava meet
The cavoatrial junction (CAJ) is the point at which the superior vena cava meets and melds into the superior wall of the cardiac right atrium. Both the superior and inferior vena cavae enter the right atrium, but only the superior entry is called the cavoatrial junction. This junction marks the inferior end of the superior vena cava, the continuation below that point being considered part of the heart.
Cavoatrial junction