DISSECTION OF THE DOG 



61 



The branches of that part of the aorta now under consideration are as 

 follows : (1) Nine or ten intercostal arteries arising from its dorsal aspect ; 

 (2) two or three small bronchial arteries arising either from the aorta itself or 

 from the first intercostal artery, and supplying the bronchial lymph-glands 

 and the oesophagus ; (3) two or three small oesophageal arteries leaving the 

 ventral aspect of the vessel. 



Ductus thoracicus. — By means of the thoracic duct the lymph from the 

 whole body, with the exception of that from the right side of the thorax, the 



(Esophagus 



vagus et truncus sympathicus 



Ganglion thoracale 



Truncus cesophageus dorsalis 



n. splanchnicus major 



n. splanchnicus minoi 



Ganglion aelmcum 

 Venfricvlus 



Ganglion cbvicale caujalt 



I n. phrenicus 



Truncus asophageus ventralis 



Diaphragma 

 Fig. 24. — Diagram of part of the sympathetic nervous system. 



right thoracic limb, and the right side of the head and neck, gains the venous 

 system. The thoracic duct begins in the abdomen between the lumbar 

 parts of the diaphragm, as a dilation known as the cisterna chyli. It enters the 

 thorax on the right side of the aorta, between this vessel and the vena azygos. 



Variable as is its thoracic course it may be said generally that, inclining 

 slightly towards the left, the duct passes for some distance through the chest 

 dorsal to the oesophagus. Afterwards it crosses the oesophagus on the left, and 

 finally opens into the left innominate vein. 



The duct is nearly always double for a greater or shorter part of its course, 

 frequent intercommunications existing between the two vessels. 



Pars thoracajjs systems sympathici. — A large, elongated ganglion, 

 the first thoracic ganglion (ganglion thoracale' primum), lies between the longus 



