SECTION II 



THE PASSAGE OF FOOD FROM THE MOUTH 

 TO THE STOMACH 



THE food after mastication is carried to the stomach by a complex series 

 of co-ordinated movements involving the muscles of the pharynx and 

 the oesophagus (Fig. 344). Various 

 methods have been used to study 

 the process of deglutition in man 

 and the higher animals. Important 

 information can be obtained by 

 allowing a man or animal to swallow 

 either a fluid or solid with which 

 bismuth is mixed, and observing the 

 passage of the opaque substance 

 under the Rontgen rays. The sub- 

 nitrate of bismuth may be mixed 

 with milk for a fluid or with bread 

 and milk for a semi-solid substance, 

 or may be enclosed in a cachet and 

 swallowed as a solid bolus. The 

 time of entry of the food into the 

 stomach may be determined by aus- 

 cultating with a stethoscope over the 

 region of the cardiac orifice. Since 

 a certain amount of air is always 

 swallowed at the same time as the 

 food, the escape of this air through 



the small cardiac orifice gives rise 

 to a bubbling noise which can be 

 easily heard. In the horse the move- 

 ment of a bolus down the oesophagus 

 can be seen or felt from the outside 

 of the neck. The relative time- 

 relations of the events at different 



FIG. 344. Dissection to show muscles 

 employed in deglutition. 



&, styloid process, from which arise 1, the 

 styloglossus ; 2, the stylohyoid ; 3, the stylo- 

 pharyngeal muscles; c, section of lower jaw; 

 d, hyoid bone; e, thyroid cartilage; g, isth- 

 mus of thyroid gland; 4, cut edge of mylo- 

 hyoid muscle ; 5, 6, 7, 8, muscles of tongue ; 

 9, 10, 11, superior, middle, and inferior 

 constrictors of pharynx; 12, oesophagus. 

 (ALLEN THOMSON.) 



parts of the oesophagus may be 

 obtained by passing sounds provided with rubber balloons to different 

 levels in the tube and connecting these sounds with recording tambours 

 46 721 



