I050 A MANUAL OF ANATOMY 



at the base of the right ventricle, and it is to be noted that it conceals the 

 origin of the aorta from the base of the left ventricle. Further, it will be seen 

 that both of these vessels are embraced by the auricular appendices. 



The right and left coronary arteries, each accompanied by the corresponding 

 coronary plexus of nerves, are to be displayed as they come forwards on either 

 side of the root of the pulmonary artery. The superior vena cava is to be 

 shown opening into the postero-superior angle of the right auricle, and, by 

 raising the heart, the inferior vena cava will be seen to open into the postero- 

 inferior angle of the right auricle. The four pulmonary veins, two right and 

 two left, will be found to open into the back part of the left auricle. 



The ascending aorta is to be dissected, and in conjunction with it the 

 trunk of the pulmonary artery, the superior vena cava being also kept in 

 view. The arch of the aorta is next to be dissected, along with the innominate 

 artery, and the thoracic portions of the left common carotid and left sub- 

 clavian arteries. 



Crossing iii front of the aortic arch will be found the left phrenic and left 

 pneumogastric nerves, and between them the superior cervical cardiac branch 

 of the left sympathetic and the inferior cervical cardiac branch of the left 

 pneumogastric, both of these two small nerves being on their way to the 

 superficial cardiac plexus. 



The left recurrent laryngeal nerve is to be shown arising from the left 

 pneumogastric opposite the lower margin of the arch of the aorta, and passing 

 backwards beneath the arch, and then upwards behind it, where it gives 

 off one or two cardiac branches to the deep cardiac plexus. The left superior 

 intercostal vein will be seen crossing over the back part of the arch on its 

 way to the left innominate vein. 



Within the concavity of the arch, in addition to the left recurrent laryngeal 

 nerve, the superficial cardiac plexus of nerves and the ligamentum ductus 

 arteriosi fall to be dissected. The superficial cardiac plexus lies in front of 

 the trunk of the pulmonary artery, close to its bifurcation, and on the right 

 side of the ligamentum ductus arteriosi, and it requires the most careful 

 dissection. The best way to proceed is to follow downwards from the front 

 of the arch of the aorta the superior cervical cardiac branch of the left sym- 

 pathetic and the inferior cervical cardiac branch of the left pneumogastric, 

 both of which will conduct to the plexus. In this plexus a small ganglion, 

 called the ganglion of Wrisberg, is to be looked for. The plexus itself will 

 be found to furnish delicate filaments to the left anterior pulmonary plexus, 

 after which it is prolonged into the right coronary plexus, which latter is 

 reinforced by fibres from the right half of the deep cardiac plexus. The 

 ligamentum ductus arteriosi will be found extending from the root of the 

 left pulmonary artery to the under aspect of the arch of the aorta immediately 

 beyond the place of origin of the left subclavian artery. 



The left lung is now to be turned well forwards, and fixed in that position 

 by hooks. The trunk of the left pneumogastric nerve is to be followed down- 

 wards behind the root of the left lung. Before reaching that point it is to 

 be shown furnishing a few branches which pass to the front of the root, and 

 there form the small anterior pulmonary plexus. Behind the root of the 

 left lung the nerve will be found to become flattened, and to break up into 

 a number of branches, which form the posterior pulmonary plexus. From 

 this plexus the nerve is to be shown issuing as two cords which pass down- 

 wards to the oesophagus, where they are to be left in the meantime. The 

 right pneumogastric nerve will be found behind the right innominate vein, 

 and on the right side of the right innominate artery and trachea. A little 

 above this point the nerve has crossed over the first part of the right sub- 

 clavian artery, and parted with the right recurrent laryngeal nerve opposite 

 the lower margin of that vessel. The right pneumogastric nerve will be seen 

 to occupy a much deeper position than the left. A branch to the deep 

 cardiac plexus should be looked for coming from it, and the main nerve is 

 to be followed downwards behind the root of the right lung, that organ having 

 been turned well forwards, and kept in that position by hooks. Behind the 

 root of the right lung the right pneumogastric nerve acts in a manner similar 



