232 HUMAN ANATOMY. 



The structure of the stomach consists of four coats, a serous,, 

 muscular, fibrous or areolar, and mucous. 



The serous coat is derived from the peritoneum, which com- 

 pletely covers it, except along the lesser and greater curvature, 

 where the vessels and nerves enter. 



The muscular coat consists of three sets of fibres : 



The longitudinal, the most superficial, are continuous below 

 with the longitudinal fibres of the small intestine below, and the 

 oesophagus above; 



The circular fibres, the second layer, are most abundant at 

 the pyloric extremity, where they form the pyloric valve; 



The oblique fibres are distributed over both surfaces, pass- 

 ing obliquely from right to left and left to right. 



The areolar or submucous coat connects the muscular with 

 the mucous layer, and is sometimes named the vascular coat. 



The mucous membrane is of a pale pinkish-ash color, thick- 

 ened toward the pylorus, where it presents numerous rugse, or 

 pleats, and at the pyloric end it helps to form the pyloric valve. 

 It is lined throughout with columnar epithelium, and is studded 

 with three kinds of minute tubes, the gastric follicles, and len- 

 ticular glands. The gastric follicles consist of two kinds, the 

 pyloric and the peptic glands, the former most abundant at the 

 pyloric end and the latter distributed all over the surface of the 

 stomach. 



The pyloric or mucous glands consist each of from two to 

 four blind tubes opening into a common duct, and lined through- 

 out by columnar epithelium. 



The peptic glands are similar in structure, but have a much 

 shorter duct, and contain in addition peculiar large, spheroidal, 

 granular peptic cells. 



The lenticular or simple solitary glands are small masses 

 of lymphoid tissue scattered throughout the connective-tissue 

 framework of the stomach between the gastric follicles. 



The arteries are derived from the gastric, pyloric, and right 

 gastro-epiploic branches of the hepatic artery, and the left gastro- 

 epiploic and vasa brevia branches of the splenic artery (vide 

 Arterial System). 



The veins terminate in the. portal, superior mesenteric, and 

 splenic veins. 



The nerves are derived from the gastric plexuses (Auer- 

 bach's and Meissner's, in the muscular and submucous coats, 

 respectively), formed by the terminal branches of the right and 

 left pneumogastric, and the branches of the coeliac plexus, an 

 offshoot of the solar plexus of the sympathetic. 



