The anatomy of the heart

The normal heart is the size of the patient’s closed fist. The venae cavae drain into the right atrium, which bears the fossa ovalis and receives the coronary sinus and the anterior cardiac vein. The atrium empties into the right ventricle through the tricuspid valve. Both ventricles have trabeculated walls (trabeculae carneae), and from some project the papillary muscles, bearing the chordae tendinae attached to the free borders of the tricuspid valve. The same arrangement is seen on the left side. The right ventricle leads to the pulmonary trunk, guarded by its three valve cusps. Oxygenated blood returns to the left atrium via the four pulmonary veins and passes to the left ventricle via the mitral valve. Exit is through the tricuspid aortic valve. The right and left coronary arteries arise above the valves, their orifices lying in the sinuses of Valsava. The right coronary artery lies in the right part of the atrioventricular groove and gives off the posterior interventricular artery. The left coronary arteries divide into the anterior (descending) interventricular branch and the circumflex branch. Major veins accompany the arteries, except for the anterior cardiac vein, which drains directly into the right atrium.