Which vessel does not empty blood into the right atrium?

The pulmonary veins are unique among the listed vessels because they serve a distinct function in the circulatory system. Unlike the superior vena cava, inferior vena cava, and coronary sinus, which all transport deoxygenated blood back to the right atrium of the heart, the pulmonary veins carry oxygenated blood from the lungs directly to the left atrium. As a crucial part of the pulmonary circulation, the pulmonary veins undertake the important task of ensuring that oxygen-rich blood is delivered for systemic distribution, making them the correct answer in this scenario.