210 NERVOUS SYSTEM. 



a few filaments to the trachea, then form a plexus which 

 surrounds the bronchial tubes and follows the bronchial tree 

 to its terminations in the air-cells. The posterior pulmonary 

 branches are larger and more numerous than the anterior. 

 They communicate freely with sympathetic filaments from 

 the upper three or four thoracic ganglia, and then form the 

 great posterior pulmonary plexus. From this plexus, a few 

 filaments go to the inferior and posterior portion of the tra- 

 chea ; a few pass to the muscular tissue and mucous mem- 

 brane of the middle portion of the oesophagus ; and a few 

 are sent to the posterior and superior portion of the pericar- 

 dium. The plexus then surrounds the bronchial tree, and 

 passes with its ramifications to the pulmonary tissue, like the 

 corresponding filaments of the anterior branches. According 

 to Sappey, the pulmonary branches are distributed to the mu- 

 cous membrane, and not to the walls of the blood-vessels. 1 



The cesophageal branches take their origin from the 

 pneumogastrics above and below the pulmonary branches. 

 These branches from the two sides join to form the cesopha- 

 geal plexus, their filaments of distribution going to the mus- 

 cular tissue and the mucous membrane of the lower third 

 of the oesophagus. 



The abdominal branches are quite different in their dis- 

 tribution upon the two sides. 



On the left side, the nerve, which is situated anterior to 

 the cardiac opening of the stomach, immediately after its 

 passage by the side of the oesophagus into the abdomen, di- 

 vides into numerous branches, which are distributed to the 

 muscular walls and the mucous membrane of the stomach. 

 As the branches pass from the lesser curvature, they take a 

 downward direction and go to the liver, and, with another 

 branch running between the folds of the gastro-hepatic 

 omentum, follow the course of the portal vein in the hepatic 

 substance. The branches of this nerve anastomose with the 

 nerve on the right side and with the sympathetic. 



1 SAPPET, Traite tfanatomie, Paris, 1852, tome ii., p. 294. 



