144 EQUINE ANATOMY. 



This membrane receives blood from the mediastinal 

 arteries ; it has also some lymphatics. 



AXGEIOLOGY. 



Arteries, — Pulmonary. — Kisesf rom the right ventri- 

 cle, runs upward and backwards in a cm*ved direction 

 and above the left auricle divides in two branches, one 

 for each lung, where thej ramify. Connections : To 

 the right with the aorta, in front and behind is em- 

 braced by the auricles and cardiac vessels ; near its 

 middle is united to the aorta by the obliterated ductus 

 arteriosus. 



Primitive aorta. — Rises from the left ventricle, 

 where it forms the sinuses of the aorta, runs upwards 

 and slightly forwards, and after two or two and a half 

 inches divides into the anterior and posterior aorta, its 

 terminal brandies. Connections : On the right with 

 the auricular mass ; on tlie left with the pulmonary 

 artery. Its collateral branches are the cardiac or cor- 

 onary arteries, divided into right and left. The right 

 rises in front of the primitive aorta, passes under the 

 anterior auricle and divides into a vertical branch 

 placed in the right vertical fissure of the ventricular 

 mass, and one horizontal running in the horizontal 

 groove. The left rises opposite the right, passes be- 

 hind the pulmonary artery under the left auricle, and 



