DEGLUTITION. 



serve merely to drive any particles of food that may be still adherent to 

 the walls of the tube, down into the stomach (Figs. 181184). 



This view, which was first put 

 forward by Kronecker and Falck, 1 

 is supported by the fact that in 

 cases where corrosive fluids have 

 been swallowed, the oesophagus has 

 been attacked only at three points, 

 where it is narrowed, and not 

 along its whole length, as would 

 be the case if the fluid were pro- 

 pelled gradually down the tube by 

 the peristaltic contraction of its 

 walls. 



The authors showed, further, FIG. 181. 



that the act of 

 swallowing 

 causes an eleva- 

 tion of pressure 

 of 20 cms. water 

 in the oesophagus, 

 and regard this 

 elevation of pres- 

 sure, due (chiefly) 

 to the contraction 

 of the mylohyoid 

 muscles, as the 

 active force 

 the onward 

 propulsion of 

 the food. 



The move- 

 men t of 

 the bolus 

 through the 

 fauces and 

 pharynx 

 is carried 

 out entirely 



by striated FIG. 183. 



muscles. In 

 the oesopha- 

 gus the bolus, 

 if too large 

 to be shot 

 through the 

 lax tube, is 

 carried down 



FIG. 182. 



Ill 



FIGS. 181-183. Curves obtained during swallowing by placing two 

 rubber balloons, one (the upper curve) in the pharynx, the other (the 

 lower curve) in the oesophagus. In Fig. 181 the second balloon was 

 4 cms. ; in Fig. 182, 12 cms. ; and in Fig. 183, 16 cms. from the upper 

 end of the cesophagus. In each curve it will be noticed that the 

 excursion of the upper lever is followed immediately by an excursion 

 of the lower lever (due to passage of the swallowed fluid and the conse- 

 quent rise of pressure), and then, after an interval of time varying 

 with the distance of the second from the first balloon, by another rise 

 of the ossophageal lever due to the contraction of the wall of that 

 tube, i.e. to the advancing peristaltic waves. Kronecker and Meltzer. 



more slowly 

 by the peri- 

 staltic contraction of its walls. These walls, in the cervical part 

 of the oesophagus, are composed of striated muscle. In the upper 



1 Arch,/. Physiol., Leipzig, 1880, S. 296, 446. 



