THE INTERCOSTAL ARTERIES. 



421 



and run outwards upon the bodies of the vertebrae, to reach the inter- 

 costal spaces. They are usually ten in number — the upper intercostal 



Fig. 274. — View of the Picr. 274. 



Thoracic and Upper 

 Part of the Abdominal 

 Aorta, &c. ^ 



For the general descrip- 

 tion of this figure, see p. 

 349. The following numbers 

 indicate the branches of the 

 aorta ; 1, placed between 

 the origins of the right and 

 left coronary arteries ; 2, 

 innominate ; 3, left carotid ; 

 4, left subclavian ; 5, bron- 

 chial ; 6, 6, cesopliageal ; 7, 

 7, intercostal arteries (sixth 

 ?<,nd seventh) ; 8, inferior 

 plirenic ; 9, cosliac axis ; 10, 

 below the superior mesen- 

 teric and opposite the origin 

 of the renal arteries; 11, 

 11, two of the lumbar ar- 

 teries. 



space, and occasionally 

 also the second, being 

 supplied by the supe- 

 rior intercostal branch 

 of the subclavian ar- 

 tery. Owing to the 

 position of the aorta to 

 the left side of the 

 spine, the right aortic 

 intercostals cross over 

 the front of the verte- 

 brae, furnishing small 

 branches to their inte- 

 Tior, and are longer 

 than the arteries of 

 the left side. The 

 vessels of both sides 

 pass outwards behind 

 the pleura, and are 

 crossed by the sym- 

 pathetic nerve : those 

 of the right side also 

 pass behind the ceso- 

 phagus, the thoracic 

 duct, and the azygos 

 vein. 



In each intercostal 

 space the artery, pass- 

 ing outwards more ho- 

 rizontally than the ril)S, crosses the space obliquely, so 

 lower border of the upper rib near its angle. It lies upon the deep 



as to gain the 



