Small cardiac vein

The small cardiac vein (right coronary vein) runs in the coronary sulcus between the right atrium and ventricle, and opens into the right extremity of the coronary sinus.

It receives blood from the back of the right atrium and ventricle; the right marginal vein ascends along the right margin of the heart and joins it in the coronary sulcus, or opens directly into the right atrium.