ARCH OF AORTA. 439 



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

 by the trunk of the pulmonary artery and the right auricular appendix, 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 rightside, it is in relation 

 with the superior vena cava and right auricle ; on the left side, with the pulmo- 

 nary artery. 



PLAN OF THE RELATIONS OF THE ASCENDING PART OF THE ARCH. 



In Front. 

 Pulmonary artery. 

 Right auricular appendix. 

 Pericardium. 

 Eemains of thymus gland. 



Right side. /Archof AortaA , Leftside. 



Superior cava. ( Ascending ] Pulmonary artery. 



Eight auricle. 



Behind. 



Eight pulmonary vessels. 

 Eoot 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. 



delations. 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. Its lower border is in relation 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 innominata vein. 

 Arteria innominata. 

 Left carotid. 

 Left subclavian. 



In front. ^ \ Behind. 



Left pleura and lung. / \ Trachea. 



Left pneumogastric nerve. / A ^ n s f v ^ s r e ta \ Cardiac plexus. 



Left phrenic nerve. I Portion. / (Esophagus. 



Cardiac nerves. \ / Thoracic duct. 



^^___^^ Left recurrent nerve. 



Below. 



Bifurcation of pulmonary artery. 

 Eemains of ductus arteriosus. 

 Left recurrent nerve. 

 Left bronchus. 



