334 



THE AOETIC ARCH. 



border of the second costal cartilage of the right side, 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 



Fig. 251. VIEW OP THE 

 THORACIC AND UPPER 

 PART OP THE ABDOMINAL 

 AORTA, SHOWING THEIR 

 RELATIONS AND PRINCIPAL 



BRANCHES J TOGETHER 



WITH A SKETCH OP THE 

 FIRST PARTS OP THE CA- 

 ROTID AND SUBCLAVIAN 



ARTERIES. 



The first ribs have been 

 divided in front of the 

 attachment of the scalenus 

 anticus muscles, and are 

 supposed to be drawn some- 

 what apart ; the rest of the 

 ribs down to the eleventh 

 are divided, along with the 

 intercostal muscles, at some 

 distance outside their angles ; 

 the internal intercostal mus- 

 cles are left in all the spaces 

 excepting the seventh and 

 eighth, in which they are 

 removed so as to expose the 

 extei-nal layer. The dia- 

 phragm has been cut trans- 

 versely near its crura, and 

 the part left behind is sup- 

 posed to be stretched up- 

 wards and to the sides. 



a, the front of the hyoid 

 bone ; b, placed on the 

 anterior scalene muscles, 

 points to the upper part of 

 the pneumogastric nerves ; 

 c, the trachea below the 

 isthmus of the thyroid 

 gland, and lower down the 

 same letter is on the left bron - 

 chus ; c', one of the divisions 

 of the right bronchus emerg- 

 ing from behind the aorta ; 

 in the hollow of the aortic 

 arch, above 5, are seen the 

 cord of the ductus arteriosus 

 cut short, and the left re- 

 current nerve passing below 

 the arch ; + , is placed on the 

 right side between the re- 

 current nerve and the ver- 

 tebral artery as they pass 

 upwards ; d, the oesophagus ; 

 e, upon the right crus of the 

 diaphragm, and farther 

 down e', mark the recepta- 

 culum chyli of the thoracic 

 duct, and its commencement 

 by the lumbar plexus of lymphatic vessels and efferent mesenteric lacteal vessels; /, on 

 the third, seventh, and eleventh ribs, points to the vena azygos and superior intercostal 



