4G> 



Arch of 

 aorta 



forms two 

 curves : 



relations. 



DISSECTION OF THE THORAX. 



sometimes another dilatation along the right side, which is named 

 the great sinus of the aorta. 



Branches. From the lower end of the ascending aorta arise the 

 two coronary arteries of the heart (fig. 170, o), which have already 

 been noticed (p. 455). 



The ARCH OF THE AORTA extends from the second right costal 

 cartilage to the lower border of the body of the fourth dorsal 

 vertebra, on the left side. The convexity of the arch is upwards, 

 and from it the three large arteries for the supply of the upper 



part of the body arise. 

 The vessel recedes from 

 the sternum, being at 

 first inclined to the 

 left across the front of 

 the trachea, and then 

 directed backwards to 

 the left side of the 

 fourth dorsal vertebra, 

 where it turns down- 

 wards to join the de- 

 scending aorta. It thus 

 forms a second curve 

 with the convexity to 

 the left side. 



The arch rests upon 

 the trachea, the oeso- 

 phagus, the thoracic 

 duct, and the fourth 

 dorsal vertebra. In 

 front of it are the 



h. Right innominate remains of the thymus 

 vein. gland, and some fat. 



i. Left upper inter- Qn the left side are the 



costal vein. 

 k. Large azygos vein. 

 I. Left subclavian vein. 

 n. Thoracic duct. 

 o. Coronary artery. 



vein. 



Fia. 170. ARCH OF THE AORTA AND 

 GREAT BRANCHES. 



Aortic arch. 

 Innominate artery. 

 Left common caro- 

 tid. 



Left subclavian. 

 Ligament of arterial 



duct. 



Vena cava superior. 

 Left innominate 



Objects con- 

 tained in the 

 arch. 



Three 



branches of 

 the arch. 



left pleura and lung, 

 and the left phrenic, 

 superficial cardiac, and 

 vagus nerves, the last 

 sending inwards its 



recurrent branch beneath the vessel. Along the upper border, in 

 front of the great branches, is the left innominate vein (fig. 171), 

 to which the left upper intercostal vein is directed over the hinder 

 part of the arch ; and to the lower border, near its termination, 

 the remnant of the arterial duct is attached. 



Below the concavity of the arch of the aorta are the root of the 

 left lung, the branching of the pulmonary artery with its arterial 

 duct, and the left recurrent laryngeal nerve. 



The three large BRANCHES of the arch supply the neck, the head, 

 and the upper limbs. First on the right is the trunk of the 

 innominate artery ; close to it is the left common carotid ; and last 

 of all comes the left subclavian. 



