Aorta. 



185 



nsin. 



Valv.post. 



The aorta, the main trunk 

 of the arterial system, arises from 

 the upper part of the left ven- 

 tricle of the heart, with an en- 

 largement, the Bulbus Aortae. It is A.subc?Qt, 

 divided into the arch o f t h e 

 aorta, thoracic aorta and 

 abdominal aorta. The arch 

 of the aorta extends from the 

 origin of the vessel to the lower 

 border of the body of the fourth 

 dorsal vertebra ; it at first ascends 

 obliquely upwards and to the right 

 side as ascending aorta, then 

 passes transversely from right 

 to left, and from before back- 

 wards as transverse aorta, 

 and then descends upon the left 



side of the body of the fourth 



, -, . , T A.coronar. 



dorsal vertebra, being there called dextrcT. 



descending aorta. 



The two coronary arte- V.dextm' 

 ries arise from the ascending por- 

 tion of the arch of the aorta, in the 

 upper parts of two of the sinuses 

 of Valsalva, on a level with the 527. Diagram of the Pri- 



margins of the scmilunar valves, mary Branches of the Arch 



The left, Arteria coronaria smistra, Q -f-hg Aorta. 



is usually larger than the right ; it 

 passes behind and then to the left 



side of the pulmonary artery. and divides into two branches; of these one 

 passes transversely outwards in the left auriculo-ventricular groove and 

 anastomoses with the superior branch of the right coronary, the other 

 descends to the apex of the heart, where it anastomoses with the descen- 

 ding branch of the right coronary. The r i g h t, Arteria coronaria dextra, 

 passes forwards to the right side in the right auriculo-ventricular groove, 

 curves backwards and divides into two branches, one of which descends 

 along the posterior interventricular furrow to the apex of the heart. 

 From the transverse portion of the arch of the aorta 

 (often simply called Arcus Aortae) three large vessels arise 5 they are : 

 the innominate artery, Art. anonyma, the left common c a r o- 

 t i d, Carotis sinistra, and the left subclavian, Art. subclavia smistra. 

 The innominate artery passes obliquely upwards and to the right 

 in front of the trachea, and divides behind the right sterno-clavicular 

 articulation into the right subclavian and right common 

 carotid arteries. The left carotid and left subclavian arteries 

 are therefore longer and placed more deeply in the thorax , than 

 the right. 



