<P> The anterior cardiac veins do not drain into the coronary sinus but drain directly into the right atrium . Some small veins known as smallest cardiac veins drain directly into any of the four chambers of the heart . </P> <Ul> <Li> <P> Diagram showing completion of development of the parietal veins . </P> </Li> <Li> <P> Posterior view of coronary circulation </P> </Li> </Ul> <Li> <P> Diagram showing completion of development of the parietal veins . </P> </Li> <P> Diagram showing completion of development of the parietal veins . </P>

Superior vena cava inferior vena cava and coronary sinus