posterior interventricular sulcus
The ventricles are separated by two grooves, one of which, the anterior longitudinal sulcus, is situated on the sternocostal surface of the heart, close to its left margin, the other posterior longitudinal sulcus (posterior interventricular sulcus, inferior interventricular groove), on the diaphragmatic surface near the right margin. In it run the posterior interventricular artery and middle cardiac vein.