ARCH OF AORTA. 363 



Relations. The ascending part of the arch is covered at its commencement by 

 the trunk of the pulmonary artery and the right auricular appendage, and, higher 

 up, is separated from the sternum by the pericardium, some loose areolar tissue, 

 and the remains of the thymus gland ; behind, it rests upon the right pulmonary 

 vessels and root of the right lung. On the right side, it is in relation with the 

 superior vena cava and right auricle ; on the left side, with the pulmonary artery. 



PLAN OF THE RELATIONS OF THE ASCENDING PAET OF THE ARCH. 



In front. 



Pulmonary artery. 

 , Eight auricular appendage. 



Pericardium. 

 Remains of thymus gland. 



Right side. f \ Left side. 



Superior vena cava. ( A ^t^ Pulmonary artery. 



Right auricle. 



Behind. 



Right pulmonary vessels. 

 Root of right lung. 



TRANSVERSE PART OF THE ARCH. 



The second or transverse portion of the arch commences at the upper border of 

 the second costo-sternal articulation of the right side in front, and passes from 

 right to left, and from before backwards, to the left side of the second dorsal 

 vertebra behind. Its upper border is usually about an inch below the upper 

 margin of the sternum. 



Relations. Its anterior surface is covered by the left pleura and lung, and 

 crossed towards the left side by the left pneumogastric and phrenic nerves, and 

 cardiac branches of the sympathetic. Its posterior surface lies on the trachea, 

 just above its bifurcation, on the great cardiac plexus, the oesophagus, thoracic 

 duct, and left recurrent laryngeal nerve. Its upper border is in relation with the 

 left innominate vein ; and from its upper part are given off the innominate, left 

 carotid, and left subclavian arteries. By its lower border, with the bifurcation of 

 the pulmonary artery, and the remains of the ductus arteriosus, which is connected 

 with the left division of that vessel ; the left recurrent laryngeal nerve winds 

 round it from before backwards, whilst the left bronchus passes below it. 



PLAN OF THE RELATIONS OF THE TRANSVERSE PART OF THE ARCH. 



Above. 



Left innominate vein. 

 Arteria innominata. 

 Left carotid. 

 Left subclavian. 



In front. ^ -. Behind. 



Left pleura and lung. ./ N^ Trachea. 



Left pneumogastric nerve- / A ? ch of \ Cardiac plexus- 



Left phrenic nerve. ( Transverse ) (Esophagus. 



Cardiac nerves. V Portion. J Thoracic duct. 



\ y Left recurrent nerve- 



Below. 



Bifurcation of pulmonary artery. 

 Remains of ductus arteriosus. 

 Left recurrent nerve. 

 Left bronchus. 



