THE HEART. 193 



trunk of the aorta, somewhat above the margins of the semi- 

 lunar valves; so that when the latter are applied against the 

 aorta, the orifices of these arteries are still visible. > 



The Right Coronary Artery begins above the anterior valve, 

 and passes to the right, beneath the pulmonary artery; it then 

 shows itself in the upper part of the fissure, between the right 

 auricle and right ventricle, and follows the course of this fissure 

 to the flat 'side of the heart. It detaches, as it goes along, se- 

 veral small branches, which come off at right angles from it. 

 One set of these branches is distributed upon the right ventricle, 

 and another set upon the right auricle. Small branches are 

 also sent from it to the root of the pulmonary artery, and to 

 that of the aorta. 



The Left Coronary Artery begins above the left semi-lunar 

 valve. While its root is still obscured by the pulmonary artery, 

 it divides into two principal branches, of which the anterior runs 

 in the fissure on the upper part of the septum of the ventricles 

 to the apex of the heart, and in this course distributes branches 

 to the right and left ventricle: those to the right anastomose 

 with the branches of the right coronary artery, which go to 

 the same ventricle. The other branch goes along the groove, 

 on the septum, between the left auricle and left ventricle, and 

 reaches the under surface of the heart; and in this course dis- 

 tributes many branches to the left auricle and left ventricle, 

 both on their upper and under surfaces. It anastomoses freely 

 with the branches of the trunk that run along the upper part of 

 the septum. 



In consequence of the frequency of the anastomoses between 

 the two coronary arteries, injecting matter thrown into one 

 very readily finds its way into the other. 



The Coronary Veins receive the blood, which is distributed 

 by the coronary arteries through the substance of the heart. 



The Great Coronary Vein (Vena Coronaria Maxima Cordis) 

 is formed by the union of several trunks, which run from the 

 apex towards the base of the heart. One of them begins at 



VOL. If. 18 



