The coronary vessels in the heart of a marsupial, Trichosurus vulpecula

The coronary arteries and veins are described in the phalanger ( Trichosurus vulpecula ), an Australian marsupial, after study of 16 hearts. Several hearts were prepared by injection of the vessels with either latex or vinyl plastic. The distributing branches of both coronary arteries are within the myocardium and are not visible on the surface of the heart. The right coronary artery arises in typical fashion and supplies the non‐septal wall of the right ventricle almost entirely, the dorsal half of the interventricular septum, the dorsal part of the non‐septal wall of the left ventricle and part of the right artium and its ventral auricle. The left coronary artery also arises typically and supplies the greater part of the non‐septal wall of the left ventricle, the ventral part of the interventricular septum, part of the infundibulum, the left atrium and part of the right atrium. At its origin it is larger than the right coronary artery. The ventral and dorsal septal arteries have an unusual course lying in the subendocardial tissue of the right ventricle. It is believed that arteries in this position have not been described previously. The great cardiac vein opens directly into the right atrium. A typical coronary sinus is present but formed only from veins draining the dorsal aspect of the heart. It is concluded that the coronary circulation in T. vulpecula closely resembles that of the avian heart and is unlike both the monotreme and placental mammalian patterns.