The venae cordis minimae (smallest cardiac veins) are the small veins of the heart proper. They drain deoxygenated blood from the capillary network in the heart wall, especially those in the myocardium. They open through the foramina venarum minimarum (small venous orifices in the endocardium) on the atrial septum and the lower parts of the lateral and anterior walls of the atrium.
There are more venae cordis minimae in the right atrium than in the other three chambers. Their openings are found in the endocardium. They allow these tiny veins to return blood into the heart cavities. Thus, the smallest cardiac veins are an alternative venous drainage system of the myocardium.
