204 



PEACTICAL PHYSIOLOGY 



lower end of the column of food tapers to a point which represents the 

 cardiac orifice of the stomach, the upper limit becoming horizontal. 

 At a comparatively slow rate the upper horizontal limit of the shadow 

 descends, the lower part remaining unaltered in shape and position 

 until the last trace of the shadow has disappeared. This means that 

 the fluid runs slowly through the narrow cardia into the stomach after 

 having been shot rapidly down the greater part of the oesophagus. 



The time which elapses between the initiation of the deglutition act 

 and the disappearance of the last trace of fluid from the oesophagus 

 should be measured with a stop-watch. It varies between four and nine 



S" 6" 



FIG. 193. Diagrams of position of shadow in oesophagus at intervals of a second 

 after swallowing. 



seconds in different individuals. About one-half of the total period is 

 required for the food to reach the lower end of the oesophagus, the 

 other half being required for its passage through the cardia. 



Fig. 193 represents diagrammatically the shadow as seen at intervals 

 of a second. 



In the horizontal position the fluid passes along the oesophagus 

 slightly less rapidly than in the vertical position. A similar but more 

 prolonged delay takes place while the food passes through the cardia, 

 the prominent end of the column being in this case rounded. Some- 

 times a small quantity of the food follows more slowly, and appears as 

 a thin streak instead of the comparatively broad band seen when the 

 oesophagus is filled. 



In the inverted position, with the head directed downwards, the 



