Gross anatomy of the cardiac blood vessels in the North American beaver (Castor canadensis).

The cardiac arteries and veins are described in the North American beaver (Castor canadensis) following the injection of the vessels of 15 hearts with either latex, vinyl plastic or barium sulfate. The left coronary artery gives off the typical circumflex and paraconal interventricular branches which supply the left atrium and ventricle and part of the right ventricle and interventricular septum. The right coronary artery vascularizes the right atrium and ventricule and by means of its subsinuosal interventricular branch, part of the left ventricle and interventricular septum. The paraconal interventricular branch of the left coronary artery lies within the myocardium and is not visible on the surface of the heart. There are no intercoronary anastomoses between the right and left vessels. The major cardiac veins open into the terminal end of the left cranial vena cava. Unlike the arteries, there are venous anastomoses interconnecting the great cardiac vein and the middle cardiac vein. It is concluded that the cardiac blood vessels in Castor canadensis are typically mammalian and resemble those of both land and aquatic mammals.