on the Structure, Distribution, and Functions of the Nerves. 127 



motions are free. Angina pectoris would seem to proceed 

 from an influence extending over these nerves and inter- 

 rupting the vital operations *; and since we have seen that the 

 division of a branch of the respiratory nerve of the face de- 

 prives it of all participation in the act of respiration and of 

 all expression, we may ask, what would be the result of a 

 more universal defect in the actions of this class of nerves but 

 sudden death? 



The par vagum being the great central nerve of this system 

 and supplying the stomach, accounts for that extraordinary 

 effect produced by a blow unexpectedly received on that re- 

 gion, which is a gasping for breath, and in some instances 

 sudden death. The position of a patient under a fit of asthma, 

 together with the other striking symptoms which mark its 

 presence, indicate that this system of nerves is under inordi- 

 nate influence. 



The actions of sneezing and coughing, instead of being ir- 

 regular or of the nature of convulsion, are an admirable pro- 

 vision for getting rid of irritating substances offending the air- 

 passages ; the extremity of one of the respiratory nerves be- 

 ing irritated occasioning all the muscles of respiration to be 

 brought into action ; the consideration of the many little mus- 

 cles which require adjustment to produce the necessary changes 

 in the direction of the stream of air for the above-mentioned 

 purpose, must lead to the conclusion of the action being in- 

 stinctive, ordered with the utmost activity, and very different 

 from convulsion. 



It was shown in the last paper, that the respiratory nerves 

 of the face were essential to the actions of smiling, laughing, 

 and weeping, as expressed in the countenance : it only remains 

 to add, in the present one, that this applies equally to the same 

 order of actions which takes place in the trunk, these being 

 produced so very distinctly under those conditions of the mind, 

 and precisely at the same time. 



These respiratory Nerves are Organs of Expression. 



We are now enabled to conceive why, in terror, a man 

 stands with eyes intently fixed on the object of his fears; the 



* Hysterical disorders also influence this system; and admitting that ir- 

 ritation reaches to the respiratory system, we may perceive how rapidly 

 tin- change may he produced, from the convulsions of laughter to those of 

 crying: this explains also the svbristu which arises from abdominal irrita- 

 tion, and the sardonic retraction of the muscles of the face produced by 

 wounds of vital parts, and particularly of the diaphragm, together with the 

 luccet ive convulsive lifting <>l the shoulders accompanying wounds of the 

 latter muscle. 



eye- 



