THE ARCH OF THE AORTA. 



383 



ABCH OF THE AOBTA. 



From the right border of the sternum, at the level of the second costal cartilage, 

 the aorta is directed at first upwards, backwards and to the left, and then directly 

 backwards, forming a well-marked curve around the trachea, to the left side of the 



Fig. 332. VIEW OP THE THORACIC AND 



GREATER PART OF THE ABDOMINAL 

 AORTA, SHOWING THEIR PRINCIPAL 



RELATIONS. (Allen Thomson. ) \ 



a, hyoid bone ; b, b, placed on the 

 anterior scalene muscles, point to the 

 pneumo-gastric nerves ; c, trachea below 

 the isthmus of the thyroid body, and 

 lower down the same letter is on the left 

 bronchus ; c', one of the divisions of the 

 right bronchus emerging from behind the 

 aorta ; in the hollow of the aortic arch, 

 above 5, are seen the cowl of the ductus 

 arteriosus cut short, and the left recur- 

 rent nerve passing below the arch ; + , is 

 placed on the right side between the re- 

 current nerve and the vertebral artery as 

 they pass upwards ; d, oesophagus ; e, e', 

 upon the right crus of the diaphragm, 

 mark the receptaculum chyli of the tho- 

 racic duct, and its commencement by the 

 lumbar and intestinal lymphatic trunks ; 

 / /> /> on the third, seventh, and eleventh 

 ribs, point to the vena azygos and inter- 

 costal veins of the right side ; y, kidney : 

 g', suprarenal body ; h, body of fourth 

 lumbar vertebra. 



7, ascending aorta : below this the 

 aortic valve is seen closed and distended by 

 injection ; /', termination of the arch ; 

 1", descending thoracic aorta ; //, abdo- 

 minal aorta. 



Branches of the aorta in the thorax : 

 1, right and left coronary arteries ; 2, 

 innominate ; 3, left common carotid ; 4, 

 left subclavian ; 5, bronchial ; 6, 6, ceso- 

 phageal ; the lower figure points by a 

 line to the thoracic duct ; 7, intercostal 

 arteries, marked in the sixth and seventh 

 intercostal spaces. 



Branches of the abdominal aorta : 8, 

 inferior phrenic arteries cut short ; 9, 

 cceliac axis with the gastric, splenic, 

 and hepatic arteries cut short ; 10, placed 

 on the aorta below the superior mesen- 

 teric artery (cut short) and the origin of 

 the renal arteries ; a little below this the 

 origin of the spermatic arteries ; below 

 //, the inferior mesenteric artery ; 11, 11, 

 two of the lumbar arteries. 



body of the fourth dorsal vertebra. 

 There it bends downwards, and 

 at the lower border of that ver- 

 tebra the arch terminates in the 



descending thoracic aorta. Its upper border, as it crosses the median plane, is 

 usually about one inch below the interclavicular notch of the manubrium. 



The arch of the aorta is contained in the superior mediastinum, and at its com- 

 mencement is separated from the manubrium by the fatty remains of the thymus 

 gland ; on each side of this it is covered, slightly on the right, to a much greater 



