The oblique vein of the left atrium is partly responsible for venous drainage; it derives from the embryonic left superior vena cava.

When the left common cardinal vein disappears in the tenth week, with the only the oblique vein of the left atrium and the coronary sinus remaining.

On the right it is limited by the sulcus terminalis of the right atrium and on the left by the ligament of the left vena cava and the oblique vein of the left atrium.

The left portion shrinks in size and eventually forms the coronary sinus (right atrium) and oblique vein of the left atrium, whereas the right part becomes incorporated into the right atrium to form the sinus venarum.