It is the lower, or inferior, part of the vena cava—a large vein also made up of the superior vena cava that carries blood from the head, neck, arms, and chest in the upper body to the heart.

In regards to blood flow, deoxygenated blood from the superior and inferior vena cava and the coronary sinus collect in the right atrium. From there, blood flows across the tricuspid valve into ...