176 



PRACTICAL PHYSIOLOGY 



Heart 



'Diaphragm ~ 



penny should be fixed over the umbilicus by means of strapping, 

 so that the position of the stomach and intestine in relation to the 

 umbilicus may be recognised. It is unnecessary to take photo- 

 graphs, but the outlines of the shadows seen on the screen should 

 be marked with blue chalk on a superimposed piece of glass, and 

 subsequently copied on to paper. 



Swallowing. The examination is begun in the vertical position. 

 A large mouthful of the opaque meal is swallowed, and its passage 

 through the oesophagus into the stomach is watched. For this 

 purpose the rays should pass in an oblique direction through the 

 thorax from the front of the right side to the back of the left side in 



order that nothing 

 should interfere 

 with the view of 

 the oesophagus, 

 which traverses the 

 clear area between 

 the shadow of the 

 heart in front and 

 that of the spine 

 behind. In the ver- 

 tical position the 

 food passes with 

 great rapidity to 

 the back of the 

 pharynx, and 

 thence equally 

 quickly down the 

 upper part of the 

 oesophagus. A 

 mouthful of ordin- 

 ary size occupies at 

 any given moment 

 between one and 

 two inches of the 

 length of the oesophagus. If several mouthfuls are swallowed in 

 rapid succession the whole of the oesophagus becomes visible as 

 a dark shadow. 



When the fluid reaches the cardia, its rapid progress is arrested 

 owing to the sudden diminution in the lumen of the oesophagus. 

 The lower end of the column of food tapers to a point which repre- 

 sents 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 



FIG. 165. Diagrams of position of shadow in 

 oesophagus at intervals of a second after 

 swallowing. 



