So8 ABDOMEN 



fibres undergo a marked increase in number, and at the 

 duodeno-pyloric constriction they are aggregated together 

 into a thick circular ring, called the pyloric sphincteric ring, 

 Fig. 196. The fibra obliqucz, or fibres, of the internal layer 

 are oblique fibres which give a partial covering to the 

 stomach. They are continuous with the deeper circular fibres 

 of the gullet, and are best seen immediately to the left of 

 the cardiac opening. From this they spread out in a series 

 of loops which embrace the oesophageal opening and proceed 

 obliquely to the right over both surfaces of the viscus. As 

 these muscular loops are traced towards the fundus, they 

 are found to gradually assume the form of a complete coating 

 of circular fibres for this part of the organ (Birmingham). 



The submucous coat is composed of lax areolar tissue. 

 It intervenes between the muscular and mucous tunics, 

 binding them loosely to each other and in such a manner 

 that the mucous membrane can glide freely upon the deep 

 surface of the muscular coat. 



The mucous coat must be studied from the inside of the 

 stomach. Open up the viscus by running the scissors along 

 the lesser curvature. The gastric mucous membrane will 

 now be seen to be thick, soft, and pulpy. In the dissecting- 

 room the student cannot obtain a proper idea of its natural 

 colour. In infancy it is rosy red, but as life advances it 

 gradually becomes paler, and in old age it presents a brownish 

 hue from the presence of pigment. When the mucous 

 membrane is cleansed and examined with a pocket-lens, its 

 surface is observed to present a pitted appearance. In- 

 numerable polygonal depressions are brought into view, and 

 these are observed to be larger and better marked near 

 the pylorus than in the vicinity of the fundus. At the 

 bottom of these pits are the mouths of the minute tubular 

 glands of the gastric mucous membrane. 



The mucous membrane has little elasticity, and, con- 

 sequently, when the stomach contracts and becomes empty 

 the membrane is thrown into projecting folds or rugae which 

 for the most part run in the longitudinal direction and 

 occupy the cavity of the organ. As the stomach expands 

 these folds open out and finally disappear when complete 

 distension is attained. 



Dissection. Extend the incision already made into the second part of 

 the duodenum upwards into the first part, to within a short distance of the 



