Middle cardiac veinThe middle cardiac vein commences at the apex of the heart. It passes posteriorly along the Posterior [interventricular sulcus|inferior interventricular sulcus] to end at the coronary sinus near the sinus' termination.StructureOriginThe middle cardiac vein commences at the cardiac apex.VariationThe middle cardiac vein has a constant location on the surface of the ventricles.Clinical significanceThe middle cardiac vein is useful for epicardial access to the inferior side of the ventricles.