VOMITING. 333 



being the chorda tj'mpani), which, together with air contained in the 

 mouth, is swallowed and so carried to the stomach. Vomiting is usually 

 preceded by a series of ineffectual retching movements, which are due to 

 spasmodic contractions of the abdominal muscles, but which are ineffective 

 from the fact that the sphincteric muscle of the oesophagus remains 

 contracted. In ejecting the contents of the stomach into the gullet, 

 when vomiting commences, a deep inspiratory movement is made, and 

 by this means the diaphragm is depressed and by its contraction forces 

 the stomach down into the abdominal cavity, while at the same time the 

 oesophagus becomes partially distended with air. The glottis is then 

 closed and the abdominal muscles again spasmodically contract, while at 

 the same time the longitudinal fibres of the oesophagus by their contrac- 

 tion serve to open the orifice of the oesophagus into the stomach. As 

 long as the diaphragm remains in its contracted position and the glottis 

 is closed, the entire force of the contraction of the abdominal muscles 

 is expended on the abdominal contents, and as a consequence the stomach 

 is firmly compressed between the abdominal walls and the diaphragm. 



The longitudinal muscular fibres of the oesophagus radiate from the 

 gullet over the walls of the stomach, and the contractions of the dia- 

 phragm having served to a certain extent to give a fixed point of 

 support to the oesophageal ends of these fibres, their contraction under 

 these circumstances will serve to pull open the orifice of the insertion of 

 the gullet into the stomach, thus overcoming the contraction of the 

 cardiac sphincter. The pressure to which the stomach is then subjected 

 by means of the contraction of the abdominal muscles forces some of 

 the contents of the stomach into the gullet, the mouth is widely opened 

 and the neck stretched to afford as straight a path as possible, and 

 the contents of the stomach are forcibly driven through the oesoph- 

 agus and ejected from the mouth. The entrance of the food into the 

 larynx is prevented by the closure of the glottis at the commencement 

 of the act, and toward its completion by a forcible expiration. Ordi- 

 narily the posterior pillars of the fauces are sufficiently closely approx- 

 imated to prevent the entrance of the ejected matter into the nasal 

 chambers; but when the vomiting is very violent their contraction is 

 overcome and the matters are forced into the nasal chambers and escape 

 by the nostrils as well as by the mouth. 



Vomiting thus consists of two distinct operations,— the active dila- 

 tation of the cardiac opening by the contraction of the longitudinal 

 fibres of the oesophagus, and the pressure of the contracting abdominal 

 muscles on the contents of the stomach. As long as the oesophageal 

 ring is tightly closed, violent contractions of the abdominal muscles are 

 entirely ineffective in expelling the contents of the stomach. Without 

 the contraction of the abdominal muscles, even though the cardiac 



