802 SPLANCHNOLOGY. 



anterior is related with the diaphragm and liver, the }30sterior 

 with the diaphragmatic flexure of the colon. The spleen lies 

 along the inferior and external part of the greater cul-de-sac, its 

 base being directed backwards and somewhat upwards ; the 

 pyloric extremity, which is placed lower than the cardiac, is 

 related with the right lobe of the liver and the intestines. 



The walls of the stomach are composed of three coats — an 

 external serous, a middle muscular, and an internal mucous coat. 



The serous coat, a reflection of the peritoneum, is smooth and 

 elastic, adhering intimately to the muscular, except at the lesser 

 curvature, where, strengthened by addition of yellow elastic tissue, 

 it forms a ligament, which appears to support the two extremities 

 of the stomach ; forming around the cardiac orifice a circular 

 fold, Avhich surrounds the oesophagus and passes to the diaphragm ; 

 this is the gastro-ijhrenic or coronary ligament. The peritoneum 

 also passes in a double fold from the greater curvature to the 

 spleen, as the gastro-splenic, to the colon as the gastro-colic, or 

 great omentum ; and from the lesser curvature to the liver, as 

 the gastro-hepatic omentum. 



In the muscular coat are three sets of fibres — an external 

 longitudinal, a middle circular, and an internal oblique layer. 

 The longitudinal are continuous with those of the oesophagus, 

 and radiate from the cardiac orifice ; they are thickest at the 

 curvatures, and are thinly scattered over the surfaces ; towards 

 the pyloric end they again converge, and form a uniform layer, 

 which is continuous with that of the duodenum. The middle 

 layer consists of circular fibres, which cover the entire organ ; 

 near the pylorus they thicken into a circular ring, which projects 

 into the orifice, and forms with a doubling of the mucous mem- 

 brane, a sphincter, called the ])yloric valve, which by contraction 

 prevents crude food from passing into the intestine. The inner 

 layer is composed of oblique fibres, continuous with the circular 

 oesophageal ones ; they are confined to the cardiac portion, 

 descend obliquely over either surface, and disap]Dear towards the 

 central constriction. All these layers are composed of pale or 

 involuntary tissue ; the longitudinal layer, by contracting, enables 

 the stomach to dilate ; the circular produces vermicular motion, 

 while the oblique layer tends to force the food from the left into 

 the right cavity ; thus there is produced a kind of churning 

 motion, which macerates the food and brings each portion of it 

 into contact with the mucous surface. 



