COUGHING ; SNEEZING ; VOMITING. 223 



sure is effective at one part only, namely, the rima 

 glottidis. 



The same remarks that apply to coughing, are almost 

 exactly applicable to the act of sneezing ; but in this in- 

 stance the blast of air, on escaping from the lungs, is 

 directed by an instinctive contraction of the pillars of the 

 fauces and descent of the soft palate, chiefly through the 

 nose, and any offending matter is thence expelled. 



In the act of vomiting, as in coughing, there is first an 

 inspiration; the glottis is then closed, and immediately 

 afterwards the abdominal muscles strongly act ; but here 

 occurs the difference in the two actions. Instead of the 

 vocal cords yielding to the action of the abdominal mus- 

 cles, they remain tightly closed. Thus the diaphragm 

 being unable to go up, forms an unyielding surface against 

 which the stomach can be pressed. It is fixed, to use a 

 technical phrase. At the same time the cardiac sphincter 

 being relaxed while the pylorus is closed (see fig. 65), and 

 the stomach itself also contracting, the action of the abdo- 

 minal muscles, by these means assisted, expels the contents 

 of the organ through the oesophagus, pharynx, and mouth. 

 The reversed peristaltic action of the oesophagus probably 

 increases the effect. 



In the act of voluntary expulsion of urine or fEeces, 

 there is first an inspiration, as in coughing, sneezing, and 

 vomiting; the glottis is then closed, and the diaphragm fixed 

 as in vomiting. Now, however, both the rima glottidis and 

 the cardiac opening of the stomach remain closed, and the 

 sphincter of the bladder or rectum, or of both, being re- 

 laxed, the evacuation of the contents of these viscera takes 

 place accordingly ; the effect being, of course, increased by 

 the muscular and elastic contraction of their own walls. 

 As before, there is as much tendency to the escape of 

 the contents of the lungs or stomach as of the rectum or 

 bladder ; but the pressure is relieved only at the orifice, 

 the sphincter of which instinctively or involuntarily yields. 



