TEE CORONARY ARTERIES. 



339 



anterior of the three sinuses of Valsalva, on a level with the margins of 

 the semilunar valves. 



The right coronary artery, about the size of a crow's quill, runs obliquely 

 towards the right side of the heart, lodged in the groove which separates 

 the auricle from the ventricle. It continues its course in the same groove, 

 along the posterior aspect of the organ, until it reaches the line of separation 

 between the two ventricles, where it divides into two branches. The smaller 



Fig. 253. 



Fig. 253. VIEW OF THE HEART AND 

 CORONARY ARTERIES FROM BEFORE (from 

 R. Quain). 



The pulmonary artery has been cut short 

 close to its origin in order to show the first 

 part of the aorta. 1, anterior part of the 

 right ventricle ; 2, left ventricle ; 3, root of 

 the pulmonary artery ; 4, ascending part of 

 the arch of the aorta ; 4', the posterior or 

 descending part of the arch ; between these 

 is seen the transverse or middle part from 

 which the brachio-cephalic arteries take their 

 origin ; 4", the descending thoracic aorta ; 

 5, the appendix and anterior part of the 

 right auricle ; 6, those of the left auricle ; 

 7, the right, and 7', the left innominate or 

 brachio-cephalic veins joining to form the 

 vena cava superior ; 8, the inferior vena 

 cava below the diaphragm ; 9, one of the 

 large hepatic veins ; +, placed in the right, 

 auriculo-ventricular groove, points to the 

 right or posterior coronary artery ; + + , 

 placed in the anterior interventricular 

 groove, points to the left or anterior coronary 

 artery. 



of these continues transversely in the 

 groove between the left auricle and 

 ventricle, approaching the termina- 

 tion of the transverse branch of the 

 left coronary artery ; while the other 

 branch runs longitudinally downwards 

 along the posterior wall of the septum between the ventricles, giving 

 branches to each ventricle and to the septum between them. 



In its course the right coronary artery gives, besides the offsets already 

 noticed, small branches to the right auricle and ventricle, and also to the 

 first part of the pulmonary artery. Along the right border of the ventricle 

 a rather large branch usually descends towards the apex of the heart, and 

 gives offsets, in its progress, to the anterior and posterior surfaces of the 

 ventricle. 



The left coronary artery is rather smaller than the preceding, and arises 

 from the left anterior sinus of Valsalva. It passes behind and then to the 

 left side of the pulmonary artery, appearing between that vessel and the 

 left auricular appendage. At first it descends obliquely towards the anterior 

 interventricular sulcus, where it divides into two branches. Of these, one 

 pursues a transverse direction, turning outwards and to the left side in the 

 groove between the left ventricle and auricle, and approaching at the 

 posterior aspect of the heart the transverse branch of the right coronary 

 artery ; the other branch, much the larger, descends on the anterior 



