Coronary Sinus

The coronary sinus is a collection of veins joined together to form a big vessel that collects blood from the heart muscle. It delivers deoxygenated blood to the right atrium, as do the superior and inferior vena cavae. It is present in all mammals, including humans. The coronary sinus drains into the right atrium, at the coronary sinus orifice, an opening between the inferior vena cava and the right atrioventricular orifice or tricuspid valve.