NERVES OF HEART SUBSTANCE. 



315 



The right coronary nerves pass from the plexus to the right coronary 

 artery, and receive near the heart a communicating offset from the deep 

 cardiac plexus. 



The left coronary nerves are derived, as will be subsequently seen from 

 the deep cardiac plexus, and accompany the left coronary artery to the 

 heart. 



At first the nerves surround the arteries, but they soon leave the vessels, 

 and becoming smaller by subdivision, are lost in the muscular substance of 



Fig. 99. 



A. Right auricle. 



B. Left auricle, with the auricula, c. 



1. Coronary sinus. 



2. Oblique vein. 



3. Vein from the right side of the heart. 



4. Left or great cardiac vein. 



j-f Veins joining the sinus from the back of the 

 ventricles. 



BACK OF THE HEART WITH THE CORONARY SINUS AND ITS VEINS. (Marshall.) 



the ventricles. On and in the substance of the heart the nerves are marked 

 by small ganglia. 



The CAVITIES OF THE HEART may be examined in the order in which 

 the current of the blood passes through them, viz., right auricle and ven- 

 tricle, and left auricle and ventricle. 



Dissection. In the examination of its cavities the heart is not to be re- 

 moved from the body. To open the right auricle, an incision may be made 

 in it near the right or free border, and from the superior cava nearly to the 

 inferior cava; from the centre of that incision the knife is to be carried 

 across the anterior wall to the auricula. By means of those cuts an open- 

 ing will be made of sufficient size ; and on removing the coagulated blood, 

 and raising the flaps with hooks or pieces of string, the cavity may be ex- 

 amined. 



The CAviTr OF THE RIGHT AURICLE (fig. 100) is of an irregular form, 1 

 though when seen from the right side, with the flaps held up, it has some- 

 what the appearance of a cone, with the base to the right and the apex 

 below and to the left. 



The base or wider part of the cavity is turned towards the right side, 



1 The term cavity of the auricle has been sometimes applied to the appendix, and 

 the term sinus venosus to the rest of the space here named auricle. 



