Blood drains from the myocardium into which chamber of the heart?

Blood drains from the myocardium, which is the muscular tissue of the heart, into the right atrium through the coronary sinus. The coronary sinus is a large vein that collects deoxygenated blood from the heart muscle itself. Once the myocardium has utilized the oxygen and nutrients delivered via the coronary arteries, it needs a way to return the used blood back to the heart. This return is facilitated by the coronary sinus which collects blood from smaller cardiac veins and empties into the right atrium.

This pathway is critical for maintaining the overall efficiency of the heart's function, allowing the heart muscle to receive a fresh supply of oxygenated blood while simultaneously removing the deoxygenated blood effectively. Other options involve pathways that do not accommodate the drainage of blood from the myocardium directly to the heart's chambers.