THORAX AND ABDOMEN OF THE HORSE 



37 



(sinus aortse), which correspond in position to the three cusps of the aortic 

 valve. 



The aortic arch has its convexity looking in a dorso-cranial direction 

 and slightly to the left of the median plane. The curve of the vessel 

 brings the aorta into contact with the vertebral column about the sixth 

 or seventh thoracic vertebra, at which point the descending aorta^ 



'A. carotis communis dextra, 

 "A. carotis communis sinistra. 



A. vertebralis sinistra. 



A. subclavia sinistra. 



A. vertebralis dextra. 

 A. sul)clavia dextra. 



5^- 



'A. carotis communis sinistra. 



A. verteliralis sinistra. 

 2 A. subclavia sinistra. 



A. carotis communis dextra. 

 A. vertebralis dextra. 

 A. subclavia dextra. 



C^' 



A. carotis communis dextra. 

 A. carotis communis sinistra. 



A. vertebralis sinistra. 



A. subclavia sinistra. 



A. vertebralis dextra. 



A. subclavia dextra. 



A. brachiocephalica. 



A. carotis communis dextra. 

 A. carotis communis sinistra. 

 Truncus bicaroticus. 

 A. vertebralis dextra. 

 A. vertebralis sinistra. 

 A. subclavia sinistra. 



A. brachiocephalica. 

 A. subclavia dextra. 

 'Truncus brachiocephalicus. 



Fig. 18. — Diagram of the arterie.s arising from the aortic arch. 

 ^= primitive arrangement ; 5 = man ; C = dog ; = horse and ruminants. 



(aorta descendens) may be assumed to begin. From the convexity of 

 the arch springs a large vessel — the common hrachio-cephalic trunk — 

 from which arise the arteries that supply the head and neck, both 

 thoracic limbs, and a considerable amount of the wall of the chest. The 

 concavity of the arch is crossed very obliquely by the pulmonary 

 artery, with which it is connected by a fibrous cord, the ligamentum 



1 The term "descending aorta" is borrowed from human anatomy and is 

 not appropriate in the domestic mammals. 



