290 VOMITING. [BOOK 11. 



whole act must be purely reflex, excited by the presence of faeces 

 in the rectum. 



Vomiting". In a conscious individual this act is preceded by 

 feelings of nausea, during which a copious flow of saliva into the 

 mouth takes place. This being swallowed carries down with it a 

 certain quantity of air, the presence of which in the stomach, 

 by assisting in the opening of the cardiac sphincter, subsequently 

 facilitates the discharge of the gastric contents. The nausea is 

 generally succeeded at first by ineffectual retching in which a deep 

 inspiratory effort is made, so that the diaphragm is thrust down as 

 low as possible against the stomach, the lower ribs being at 

 the same time forcibly drawn in; since during this inspiratory 

 effort the glottis is kept closed, no air can enter into the lungs ; 

 but some is drawn into the pharynx, and thence probably descends 

 by a swallowing action into the stomach. In actual vomiting this 

 inspiratory effort is succeeded by a sudden violent expiratory 

 contraction of the abdominal walls, the glottis still being closed, so 

 that the whole force of the effort is spent, as in defecation, in 

 pressure on the abdominal contents. The stomach is therefore 

 forcibly compressed from without. At the same time, or rather im- 

 mediately before the. expiratory effort, by a contraction of its longi- 

 tudinal fibres the oesophagus is shortened and the cardiac orifice 

 of the stomach brought close under the diaphragm, while ap- 

 parently by a contraction of the fibres which radiate from the end 

 of the oesophagus over the stomach, the cardiac orifice, which is 

 normally closed, is somewhat suddenly dilated. This dilation opens 

 a -way for the contents of the stomach, which, pressed upon by the 

 contraction of the abdomen, and to a certain but probably only to 

 a slight extent by the contraction of the gastric walls, are driven 

 forcibly up the oesophagus, their passage along that channel being 

 possibly assisted by the contraction of the longitudinal muscles. 

 The mouth being widely open, and the neck stretched to afford as 

 straight a course as possible, the vomit is ejected from the body. 

 At this moment there is an additional expiratory effort which 

 serves to prevent the vomit passing into the larynx. In most 

 cases too the posterior pillars of the fauces are approximated, 

 in order to close the nasal passage against the ascending stream. 

 This however in severe vomiting is frequently ineffectual. 



Thus in vomiting there are two distinct acts ; the dilation of 

 the cardiac orifice and the extrinsic pressure of the abdominal walls 

 in an expiratory effort. Without the former the latter, even when 

 distressingly vigorous, is ineffectual. Without the latter, as in 

 urari poisoning, the intrinsic movements of the stomach itself are 

 rarely sufficient to do more than eject gas, and, it may be, a very 

 small quantity of food or fluid* Pyrosis or waterbrash is probably 

 brought about by this intrinsic action of the stomach. 



During vomiting the pylorus is generally closed, so that but 

 little material escapes into the duodenum. When the gall-bladder 



