Arterial system of the atrium in the human heart

We dissected the atrial arterial system of 22 adult human hearts from donated cadavers. Atrial branches (ABs) of coronary arteries, more than 0.5 mm in diameter at their origin, were selected to trace systematically their origin and course. A total of 135 ABs were observed, of which 68 were from the circumflex branch, and 67 from the right coronary artery. The origins of ABs were classified into the following five regions where they arose from coronary arteries: (A) from the left aortic bulb to the one-third of the left auricle, (B) from the end of region A to the point of anastomosis of the coronary sinus (CS) with an oblique vein of the left atrium (OVLA), (C) from the end of region B to the opening of the CS, (D) from the end of region C to two-thirds of the right auricle, (E) from the end of region D to the right aortic bulb. With regard to the course of the ABs, they were classified according to the following 8 areas where they passed: (I) underneath Bachmann's bundle (BB); (II) the area connecting the right and left superior pulmonary veins; (III) the dorsal part of the interatrial septum; (IV) beside the OVLA; (V) the atrial side beside the CS; (VI) the ventral part of the interatrial septum; (VII) the dorsal wall of the left atrium; (VIII) on the dorsal surface of the right atrium. Thus, ABs showed various combinations of regions and courses.