THE CRANIAL OB ENCEPHALIC NERVES. 735 



ficially than the right in the lower part of the neck, and for this reason 

 should be more exposed to compression. He thus explains wliy, in chronic 

 " roaring " the alterations observed are nearly always in the left muscles 

 of the larynx. 



The terminal divisions of the recurrents are distributed to the posterior 

 and lateral crico-arytenoid, and the arytenoid and thyro-arytenoid muscles, 

 as well as to the subglottic mucous membrane. 



In their long course, they emit collateral ramuscules that also ascend, 

 and are distributed to the mucous membrane and muscular layer of the 

 trachea, as well as to that of the ossophagus. 



The recurrent cesophageal ramuscules are all sensitive, and form five 

 groups : the first and second arise, on the left side, close to the arch of the 

 aorta, ascend on the sides of the trachea, and pass to the portion of the 

 oesophagus lying between that canal and the thoracic section of the longus 

 colli muscle. The third, more considerable, springs from a branch that is 

 given off at the brachial trunks ; it is markedly recurrent, and forms 011 

 the side of the trachea, with the second, a small plexus, and then lies 

 closely alongside the oesophagus, which it accompanies for a distance of 

 eight inches from the first rib. The branch constituting the fourth group 

 is the longest of all ; it is detached about two or two and a-half inches in 

 front of the first rib, and after emitting several long tracheal filaments, it 

 ascends on the side of the trachea close to the border of the oesophagus, 

 where it generally disappears at about six or eight inches from the pharynx. 

 The fifth group is composed of a branch detached from the recurrent, about 

 the point where the preceding terminates ; it goes entirely to the origin 

 of the canal. 



TERMINAL BRANCHES OF THE PNEUMOGASTR10 NERVES. 



1. BRONCHIAL PLEXUS (Fig. 362, 29). The bronchial plexus is formed 

 oy several branches from the pneumogastric, on the arrival of that nerve 

 above the roots of the lungs, and which interlace in a network and ramify 

 around the bronchial divisions following these into the texture of the 

 pulmonary organ. It is these branches which give to the mucous membrane 

 its great sensibility, and which provoke those evident contractions of which 

 it is the seat. 



2. (ESOPHAGEAL BRANCHES (Fig. 362, 30, 31). After emitting the 

 ramuscules of tlfls bronchial plfe'xus, each pneumogastric is continued along 

 the oesophagus by two branches a superior and inferior making four 

 branches for the two nerves. The two superior lie together, and are 

 confounded in a single cord, either immediately, or after a certain course ; 

 the two inferior comport themselves in the same manner with one another ; 

 making a double anastomosis, from which arise the two nerves we are 

 about to describe, and which are designated the cesoplmgeal nerves, because 

 of their situation. The right nerve forms a large portion of the superior 

 cord ; the left, especially, gives ramuscules to the inferior. 



Placed between the layers of the posterior mediastinum, these two 

 nerves follow the oesophagus for a certain distance, one above, the other 

 below, giving off some ramuscules to that muscular canal, detaching one or 

 two communicating branches, and traversing the opening in the right 

 pillar of the diaphragm to penetrate the abdominal cavity. 



The inferior terminates in the parietes of the stomach, by forming 

 on the small curvature, to the right of the cardia, a very rich plexus 



