220 NEKVOUS SYSTEM. 



galvanism was applied to the nerves also show an arrest of 

 respiration ; but it is argued that there is nothing special in 

 the action of the superior laryngeals under these conditions, 

 inasmuch as other sensitive nerves have been found to act 

 in the same way. 1 This is undoubtedly true ; but it is well 

 known that, in living animals, strong impressions made upon 

 any of the acutely sensitive nerves arrest respiration, and 

 that this is one of the phenomena commonly observed in 

 animals struggling under painful operations. In view of 

 these facts, it seems unnecessary to discuss more fully the 

 numerous experiments on the effects upon respiration of 

 stimulation of the superior laryngeals ; and we can assume 

 that it has been demonstrated that an impression made -upon 

 the terminal filaments of these nerves, such as occurs in the 

 ordinary process of deglutition, excites, by reflex action, con- 

 traction of the constrictors of the pharynx, and, at the same 

 time, momentarily suspends the movements of the diaphragm. 

 Important experiments have been made within the past 

 few years, upon the action of the pneumogastrics on the cir- 

 culation, in which it is claimed that nervous filaments, arising, 

 in the rabbit, in part from the trunk of the pneumogastric 

 and in part from the superior laryngeal branch, act as reflex 

 depressors of the vascular tension. These experiments will 

 be fully discussed in connection with the cardiac branches. 



Properties and Functions of the Inferior, or Recurrent 

 Laryngeal Nerves. The anatomical distribution of these 

 nerves shows that their most important function is con- 

 nected with the muscles of the larynx. The few filaments 

 which are given off in the neck to join the cardiac branches 

 are probably not very important. It is proper to note, how- 

 ever, that it supplies the musculai tissue and mucous mem- 

 brane of the upper part of the oesophagus and the trachea, and 

 one or two branches are sent to the inferior constrictor of 



1 BERT, Le$ons sur la physiologic comparee de la respiration, Paris, 1870, p. 

 459, et seq. 



