212 NERVOUS SYSTEM. 



cult of demonstration. In treating cf the functions of this 

 nerve, we shall be compelled to make constant reference to 

 its anatomy, and for that reason have described pretty fully 

 in detail most of the important points in its connections and 

 distribution. 



Although the extensive distribution of the pneumogas- 

 trics and their importance will necessitate a long discussion 

 of their physiology, we shall endeavor to separate the points 

 to be considered distinctly, and simplify the subject as much 

 as possible. 



We shall first treat of the general properties of those fila- 

 ments derived from the true roots of the nerves, and, follow- 

 ing them in their course, shall note the properties derived 

 from their connections with other nerves. 



We shall then treat of the properties of the different 

 branches of the nerves, under distinct heads, taking up these 

 branches as they are given off, from above downward. In 

 this, we shall consider first the properties and functions 

 of the auricular branches ; next, of the pharyngeal branches, 

 with their influence upon the action of the pharynx in deglu- 

 tition ; next, the superior and inferior laryngeal branches, 

 with their relations to the physiology of the larynx ; next 

 the cardiac branches, with their influence on the move- 

 ments of the heart and the circulation ; next, the pulmonary 

 branches, with the function of the nerves in connection with 

 respiration ; next, the oesophageal branches, in connection 

 with the influence of the nerves upon the action of the 

 oesophagus, in deglutition ; next, the abdominal branches, 

 with the influence of the nerves in connection with diges- 

 tion and the functions of the abdominal viscera. By divid- 

 ing up, in this way, the action of the pneumogastrics, it is 

 hoped that their physiology may be relieved of much of 

 the complexity in which it is apparently involved. 



General Properties of the Hoots of Origin of the Pneu- 

 mogastrics. All who have operated on the pneumogastrics 



