Location
It runs transversely in the groove between the left atrium and left ventricle on the posterior surface of the heart.
The coronary sinus orifice (opening, also known as the ostium of the coronary sinus) is on the posterior, inferior surface of the heart, medial to the inferior vena cava opening, just superior to the septal leaflet of the tricuspid valve. The coronary sinus orifice is guarded by the Thebesian valve.
Read more about this topic: Coronary Sinus