138 



ANATOMY AND PHYSIOLOGY 



rugae, running from one extremity to the other the longitudinal 

 folds. This layer contains the gastric glands which secrete the 

 gastric juice and pour it through their ducts into the stomach. 



The submucous layer or submucosa is a network of connective 

 tissue next to the mucous coat. It bears fine vessels, nerves and 

 lymphatics, and connects the mucous and muscular tunics together 

 loosely, so that when the stomach is distended the longitudinal folds 

 simply disappear, without injury to the mucous membrane. 



The muscular coat (or tunic] comprises three layers of non- 

 striated muscle: internal, middle and external. The internal layer 



Aorta 



CeLac artery 



Gastric artery 



FIG. 104. THE STOMACH AND SPLEEN. (Morris.} 



consists of oblique fibers (it is a thin layer and is mostly con- 

 fined to the cardiac portion). The middle layer is a complete 

 layer of circular fibers. They are most numerous at the ex- 

 tremities of the stomach, where they form two ring-shaped 

 bundles. One is the sphincter of the cardia, surrounding the lower 

 end of the esophagus and the cardiac orifice of the stomach; the 

 other is the sphincter of the pylorus, which is a strong ring-muscle 

 diminishing the size of the pyloric orifice so that it is the narrowest 

 portion of the alimentary tract (a half-inch, or 3 mm.). The ex- 

 ternal layer consists of longitudinal fibers (fibers running length- 



