CROUP. 19 



rowing of the glottis, and the occurrence of which, where there Is no 

 talse membrane, requires further explanation, is peculiar, and not easily 

 confounded with any other form of impeded respiration. In the first 

 place, it is tremendously laborious. The efforts made by the child, in 

 order to draw breath, are very evident. Every muscle, which can aid 

 in expanding the chest, is called into vehement action. He sits up, 

 extends his spinal column, so as more effectually to dilate the thorax by 

 upheaval of the ribs. In spite, however, of every effort, the air can pass 

 but slowly through the contracted rima glottidis. The breathing is re- 

 markably protracted and tedious, and hence, of course, much less fre- 

 quent than in dyspnoea from other causes (pneumonia, for instance, 

 where the muscles of respiration have no abnormal obstacle to over- 

 come). It also gives rise to an exceedingly characteristic wheezing or 

 sawing sound, which, if once heard, will always be recognized in future. 



During these laborious efforts at inspiration, the levatores alae nasi 

 contract, dilating the nostrils (for, without this instinctive muscular ac- 

 tion, the nostrils would tend to close, from the rapid rarefaction of the 

 ah* within the nose). This "working of the nostrils," however, is not 

 pecuh'ar to the dyspnoea of croup. 



Besides this, however, there is another and characteristic sign of 

 croup, which is known even to the laity, and which depends upon the rare- 

 faction of the air within the thorax, when dilated during stricture of the 

 glottis. We see, namely, that with every inspiration the epigastrium, 

 instead of projecting, is strongly and deeply depressed. When the air 

 within the chest becomes rarefied, the pressure upon the thoracic surface 

 of the diaphragm becoming far lighter than that upon its abdominal 

 surface, it yields, and is forcibly pushed upward, the xyphoid and costal 

 cartilages being likewise drawn in by the inspiration. This, too, is 

 easy of comprehension, if we only bear in mind the mechanism of normal 

 respiration. If the air can enter the air-passages with freedom, the dia- 

 phragm, upon contracting, causes its pars tendinea to descend, but pro- 

 duces no incurvation of the ribs ; for their resisting power is far greater 

 than that encountered by the diaphragm in the elasticity of the lung, or 

 in the feeble pressure of the abdominal viscera. 



If, however, the tendinous centre be drawn up by the rarefaction of 

 the air in the lungs, or if it be only fixed and hindered from moving 

 downward, the inspiratory contractions of the muscles of the diaphragm 

 must then, of necessity, cause the arch of the ribs to curve inward. 

 The desire to draw breath, the efforts to do so, and the desperation 

 which its fruitless exertions produce, are evinced in the entire being 

 of the child. Now it begs to be taken out of bed into the arms of its 

 nurse, and fram its nurse to be put to bed again. The greatest terror 

 is depicted in its manner; it beats about, throws itself hither and thithei, 



