CHAP. XXIV.] THE STOMACH. 191 



fibres are not regularly longitudinal and circular as in the oesophagus, 

 and as in the intestines. The outer or longitudinal set may be best 

 traced along the lesser curvature and near the pylorus ; and those 

 beneath cross them either at right angles or obliquely, according to 

 their situation. Towards the lesser extremity the fibres of both 

 layers are much thicker, and particularly so at the pylorus itself, 

 where they form a circular constriction projecting the lining mem- 

 brane, and capable of acting as a sphincter muscle. They are of the 

 unstriped variety. 



The mucous membrane of the stomach is thick and soft, and thrown 

 into numerous irregular folds by the contraction of the muscular coat, 

 except in the distended state of the organ. To be capable of this 

 folding, it is separated from the muscular wall by a very lax areolar 

 tissue, containing no fat, but filled with the vessels belonging to the 

 mucous membrane, and also containing nerves. This is the coat 

 wrongly styled nervous by the older writers. 



The stomach is freely supplied with blood by the three divisions 

 of the coeliac axis, the coronary, hepatic, and splenic. The branches 

 of the arteries reach it along its borders, soon pierce its muscular 

 tunic, and form plexuses in the sub-mucous areolar tissue, where they 

 break up into numberless finer ramifications, which penetrate the 

 mucous coat. The veins accompany the arteries in their distribu- 

 tion, and discharge themselves into the vena portre. Both orders of 

 vessels are very tortuous, and their contiguous branches everywhere 

 anastomose freely, so as to distribute the sanguineous supplies equally 

 during the changing volume of the organ. The nerves of the sto- 

 mach are derived from the pneumogastrics and from the cceliac 

 plexus. They advance from the lesser curvature over both surfaces, 

 and after supplying the muscular walls, enter the areolar layer under 

 the secreting lining membrane. 



The mucous membrane of the stomach demands and will well re- 

 pay an attentive study. It is of that variety which has been termed 

 compound mucous membrane, i. e. its thickness is made up of an in- 

 finite multitude of tubular involutions of the simple membrane, with 

 intermediate vascular, and other tissues sent up into it from below. 

 The simple membrane consists of basement membrane and epithe- 

 lium, both of which are found throughout. The vessels are uni- 

 formly on the deep surface of the basement membrane, and the 

 epithelium on its opposite surface. The compound mucous mem- 

 brane of the stomach is thinnest near the oesophagus, and is usually 

 of a pinker colour in the middle region, and paler towards the 

 pylorus. 



