404 ANGIOLOGY. 



three small vessels which arise at the hiatus aorticus : one goes 

 to the left, the other to the right diaphragmatic crus, terminat- 

 ing on the phrenic centre. The right gives twigs to the pleura 

 and right lung. 



The MIDDLE SACRAL artery is a single median continuation of 

 the posterior aorta. Large in some animals, when present in the 

 horse it is extremely rudimentary, and it is often absent. 



VISCERAL BRANCHES. 



Broncho-cesophageal. Thoracic. 



Cceliac axis. 



Great mesenteric. 



Small mesenteric. 



Renal. 



Spermatic. 



Small testicular. 



The BRONCHO-CESOPHAGEAL arises close to and sometimes with 

 the first pair of aortic intercostals, breaking up into bronchial 

 and cesophageal branches. The bronchial arteries pass between 

 the aortic arch and the oesophagus, to the bifurcation of the 

 trachea, dividing into right and left, which enter the lungs with 

 the bronchi, ramifying with the air-tubes, and terminating in the 

 pulmonary capillaries. The oesophageal artery proceeds back- 

 wards to the posterior mediastinum ; reaching the oesophagus, it 

 divides into two. The large superior one is distributed to the 

 upper, the inferior to the under surface, anastomosing with the 

 pleural branch of the gastric, and supplying the posterior 

 mediastinum. 



CCELIAC AXIS. 



(Fie. 155. 1.) 



This is a short trunk arising from the lower surface of the 

 aorta, as it enters the abdomen. About an inch in length, it 

 divides into the gastric, splenic, and hepatic arteries. 



The GASTRIC, the central and smallest division, passes the 

 cardiac orifice of the stomach, and divides into right or anterior, 

 left or posterior, and pleural ; the latter enters the thorax by the 

 foramen sinistrum, bifurcates and anastomoses with the cesophageal 

 a.v>d suoerior branches of the thoracic artery. The right gastric 

 passes to the oesophagus over the lesser curvature of the stomacii, 



