222 FUNCTIONS OF THE NERVOUS SYSTEM. 



Hall has pointed out an important distinction between Epilepsy and Hysteria, 

 which materially influences the proximate danger of the paroxysm of each 

 respectively; in the former, the larynx is convulsively closed and partial 

 asphyxia is the necessary result, if the access of air be too long prevented, so 

 that venous congestion ensues, increasing the disorder of the nervous centres 

 even to a fatal degree ; in Hysteria, on the contrary, much as the larynx is 

 affected, it is not usually closed. Cases sometimes present themselves, how- 

 ever, in which the Hysteric paroxysm assumes the Epileptic character, the 

 larynx being closed during expiration, so as to produce alarming results. 



300. The foregoing are the chief general spasmodic diseases in which the 

 Spinal system of nerves is evidently involved ;* but there are many others of 

 a more local character. Such are the various forms of Spasmodic Asthma, the 

 attacks of which generally result from some internal irritation, either in the 

 lungs themselves or in the digestive system, producing a reflex action upon the 

 muscular fibres of the bronchial tubes. The Croup-like Convulsion, or Crow- 

 ing Inspiration of Infants, again, is an obstruction to the passage of the air 

 through the glottis, by a spasmodic contraction of the constrictors of the larynx. 

 This spasmodic action may be induced by various kinds of irritation ; such as 

 that occasioned by teething, by the presence of undigested food, or by intestinal 

 disorder. In the crowing inspiration, the larynx is partially closed ; when the 

 spasm is severe, however, there is complete occlusion of the passage ; and 

 forcible efforts at expiration are made, which induce, as in epilepsy, a severe 

 degree of venous congestion, and this reacts upon the nervous centres, aggra- 

 vating the previous disorder of their condition. The present increased know- 

 ledge of the functions of the laryngeal nerves, and of the symptoms of this 

 disease, appears to render inadmissible the explanation of it given not long 

 since by Dr. H. Ley, who attributed it to paralysis of the pneumogastric nerves 

 occasioned by pressure. Spasmodic closure of the larynx may occur from 

 other causes. When the rima-glottidis is narrowed, by effusion of fluid into 

 the substance of its walls, it is very liable to be completely closed by spas- 

 modic action, to which the unduly irritable condition of the mucous membrane 

 will furnish many sources of excitement. Choking, again, does not result so 

 much from the pressure of the Food on the air-passages themselves, as from the 

 spasmodic action of the larynx, excited by this ; and the dislodgment of the 

 morsel by an act of vomiting is the most effectual means of obtaining relief. 

 Tenesmus and Strangury are well-known forms of spasmodic muscular con- 

 traction, excited by local irritation acting through the Spinal system. The 

 abnormal action which leads to Abortion is frequently excited in the same 

 manner ; how far the uterus itself is called into contraction by the ordinary 

 spinal nerves, is a question as yet undecided ; but the facts already stated leave 

 no doubt, that stimuli operating on these may act upon it through the Sympa- 

 thetic, into which their fibres pass ( 203). It will be borne in mind, how- 

 ever, that, in abortion, as in ordinary parturition, many muscles are called in, 



* Chorea is ranked by Dr. M. Hall as a disease of the Spinal System of nerves; but 

 this can scarcely be regarded as a correct determination. It is true that there is consi- 

 derable irregularity in the ordinary Reflex actions; but the irregularity is still greater in 

 those to which Volition or Emotion is the stimulus. Moreover, the body is at rest during 

 sleep; and the "Spinal system never sleeps." The frequent origin "of the disease in 

 causes which have excited strong mental emotions, and the effect of even moderate excite- 

 ment of the feelings in greatly aggravating ihe movements of the body, seem to indicate 

 the connection of this disease with the Emotional system of nerves. Stammering may 

 be regarded as a sort of Chorea affecting the muscles of voice: of this, more hereafter 

 (CHAP. vr.). In Paralysis Agitans, it may be usually observed that the voluntary actions 

 are much more affected than the reflex; the latter, indeed, not in general manifesting any 

 disturbance. An interesting and well-marked case of this disease has been mentioned 

 to the author by Dr. W. Budd, in which softening was found in the Crura Cerebri. 



