Which vein should not empty into the coronary sinus?

The superior vena cava does not empty into the coronary sinus, making this choice correct. Understanding the anatomy of the heart and its venous drainage is crucial in this context.

The coronary sinus is a large venous structure located in the atrioventricular groove that collects blood from the heart muscle itself, specifically the myocardium. It receives blood from several important veins, including the great cardiac vein, the middle cardiac vein, and the small cardiac vein, among others. However, the superior vena cava and inferior vena cava primarily drain deoxygenated blood from the systemic circulation directly into the right atrium, bypassing the coronary sinus altogether.

The great cardiac vein, which runs alongside the left anterior descending artery, drains blood from the anterior part of the heart and directly empties into the coronary sinus. The left atrial vein, while not commonly referenced, would typically be included in the broad context of pulmonary veins, which return oxygenated blood from the lungs to the left atrium, and again, do not drain into the coronary sinus.

Thus, the specificity of the superior vena cava’s drainage directly into the right atrium, rather than into the coronary sinus, establishes it as the correct answer.