CHAPTER YII. 



DEGLUTITION. 



Physiological anatomy of the parts concerned in deglutition Pharynx Muscles 

 of the pharynx Muscles of the soft palate Mucous membrane of the phar- 

 ynx (Esophagus Mechanism of deglutition First period of deglutition 

 Second period of deglutition Protection of the posterior nares during the 

 second period of deglutition Protection of the opening of the larynx Func- 

 tion of the epiglottis Study of deglutition by auto-laryngoscopy Third period 

 of deglutition Intermittent contraction of the lower third of the oesophagus 

 Nature of the movements of deglutition Deglutition of air. 



Deglutition. 



DEGLUTITION is the act by which solid and liquid articles 

 -ire forced from the mouth into the stomach. The process 

 involves first, the passage lay a voluntary movement of the 

 alimentary mass through the isthmus of the fauces into the 

 pharynx ; then a rapid contraction of the constrictors of the 

 pharynx, by which it is forced into the oesophagus; and, 

 finally, a peristaltic action of the muscular walls of the 

 oesophagus extending from its opening at the pharynx to the 

 stomach. 



Physiological Anatomy of the Parts concerned in Deg- 

 lutition. The parts concerned in this function are the 

 tongue, the muscular walls of the pharynx, and the oeso- 

 phagus. In the passage of food and drink through the 

 pharynx, it is necessary to completely protect from the en- 

 trance of foreign matters a number of openings which are 

 exclusively for the passage of air. These are the posterior 



