DEGLUTITION. 



119 



leglutition is commonly divided into three so-called stages, 

 tween which, however, it is by no means easy to draw a hard 

 md fast line. 



The first stage is simply the initiatory step of placing the mor- 

 sel of food or some liquid in such a position as to excite the 

 second or spasmodic act of deglutition. This first step is a volun- 



FIG. 53. 





Transyerse section of (Esophagus (Horsley). a. Outer fibrous covering. 6. Bundles of 

 longitudinal muscle cut across, c. Transverse muscular coat cut obliquely, d. Sub- 

 mucous coat with glands in section, e. Muscularis mucosse. /. Mucous membrane with 

 cut vessels, g. Stratified epithelium. 



tary act, and it is the only part of the movements of swallowing 

 over which we have any voluntary control. The progress of the 

 morsel between the tongue and palate toward the fauces may be 

 as slow and gradual as we wish, but the moment a certain point 

 is reached volition is at an end, and we are unable to check the 

 completion of the act. 



