What two major veins return blood to the right atrium?

The two major veins that return blood to the right atrium are the superior vena cava and inferior vena cava. The superior vena cava is responsible for returning deoxygenated blood from the upper part of the body, including the head, neck, arms, and upper torso, back to the heart. In contrast, the inferior vena cava returns deoxygenated blood from the lower part of the body, including the legs, abdomen, and pelvis.

Understanding the roles of these veins is essential for grasping the overall anatomy and physiology of the circulatory system. The right atrium then receives this deoxygenated blood before it flows into the right ventricle, which pumps it to the lungs for oxygenation. This process highlights the critical function of the superior and inferior vena cava in the systemic circulation and the heart's role in maintaining effective blood flow throughout the body.