THE ARCH OF THE AORTA. 



347 



ing at the same time more nearly to that bono. Havin.o- "•ained the 

 level of the upper border of the second costal cartilage of the right side, 



Fig. 242. 



Fig. 242, A. — The 

 Aorta from before, 

 with- the origins op 

 its principal branches 

 (E. Quain). i 



1, the aorta at the 

 place where it has been 

 separated from the left 

 ventricle, showing the 

 semilunar valves . in a 

 closed condition, the 

 sinuses of Valsalva, and 

 the origin of the right 

 and left coronary arte- 

 ries ; 2, the ascending 

 part of the arch, with 

 the dilatation termed 

 sinus ; 3, the third part 

 of the arch ; 4, innomi- 

 nate arterj' ; 5, left 

 carotid ; 6, left subcla- 

 vian ; 7, concavity of 

 the middle part of the 

 arch ; and farther down 

 the aorta, 7. 7, iiidicate 

 two out of the series of 

 intercostal and lumbar 

 arteries : the oesophageal 

 arteries are also seen 

 rising from the front of 

 the thoracic aorta ; 8, S, 

 right and left renal arte- 

 ries ; 9, 9, right and left 

 common iliac arteries ; 



10, middle sacral artery; 



11, one of the inferior 

 diaphragmatic arteries ; 

 + , the cceliac axis ; 12, 



the gastric artery ; 1 3, 

 the hepatic ; 14, the 

 splenic ; 15, superior 

 mesenteric ; 16, inferior 

 mesenteric ; 17, 17, right 

 and left sijermatic arte- 

 ries. 



Fig. 242, B. — The 

 SAME Aorta from 

 BEHIND. (R. Quain). | 



The numbers have the 

 same signification as in 

 A. The origin of tlie 

 right and left inter- 

 costal arteries close to 

 eacli other from near the 

 middle line of the posterior wall of the aorta is shown. 



the vessel alters its course, and is directed upwards, backwards, and to- 

 the left side, then directly backwards, in contact with the trachea, to the 

 left side of the body of the second dorsal vertebra. Arrived at that pointy 



