Heart
Atria and Ventricles



The external surface of the heart with the great vessels and the coronary arteries and veins.
The heart lies in the middle mediastinum, enclosed by the pericardium, with its apex directed downwards, forwards and to the left. The right and left coronary arteries arise from the aortic sinuses and run in the coronary and interventricular sulci, while most cardiac veins drain into the coronary sinus.