THE ABDOMEN 783 



At the deepest part of the mucous coat, and forming a part of 

 it, there is a stratum of plain muscular tissue, called the muscularis 

 mucoscB {muscularis interna), which is disposed in two layers — outer 

 longitudinal, and inner circular. The mucous membrane is also 

 provided with lymphoid tissue in the interspaces between the deep 

 ends of the gastric glands. In the cardiac part of the stomach this 

 lymphoid tissue occurs in the form of isolated collections, called 

 lymph follicles, which bear a resemblance to the solitary glands of 

 the intestinal mucous membrane. In the neighbourhood of the 

 pylorus these lymph follicles become aggregated, and so resemble 

 somewhat the agminated glands or Peyer's patches of the small 

 intestine. 



Blood-supply — Arteries. — Along the small curvature there are 

 (i) the gastric branch of the coeliac axis in two divisions, and 

 (2) the pyloric branch of the hepatic, also in two divisions. Along the 

 great curvature there are (1) the right gastro-epiploic of the gastro- 

 duodenal of the hepatic from the cceliac axis, and (2) the left gastro- 

 epiploic of the splenic from the coeliac axis. At the fvmdus there 

 are the vasa brevia of the splenic artery. 



The branches arising from all these arteries enter the muscular 

 coat without piercing the peritoneum. They subsequently make 

 their way inwards to the submucous coat, where they break up into 

 branches which freely anastomose with one another. Fine branches 

 then enter the mucous coat, which rim upwards between the 

 closely- packed gastric glands, round which they form by their 

 anastomoses a delicate capillary network with its meshes elongated 

 in the direction of the gland-tubes. From this network somewhat 

 larger vessels proceed upwards, which by their anastomoses form 

 a coarser and more superficial network around the orifices of the 

 ducts of the glands. 



Veins. — ^These arise from the superficial network of capillaries 

 round the orifices of the ducts of the glands. They take a down- 

 ward course between the gland- tubes, and on reaching their deep 

 ends they form a plexus. From this plexus branches proceed 

 outwards to the submucous coat, in which they form another 

 plexus. The branches arising from this latter plexus, having passed 

 through the muscular coat, terminate in the following veins : 

 (i) the right gastro-epiploic, which opens into the superior mesen- 

 teric ; (2) the left gastro-epiploic and vasa brevia, which open into 

 the splenic ; (3) the gastric ; and (4) the pyloric, the latter two 

 opening directly into the vena portae. The veins of the stomach 

 contain numerous valves, which are sufficiently competent in 

 early life to oppose the return of venous blood, but in the adult 

 [ they are incompetent. 



j Lymphatics. — These commence near the free surface of the mucous 

 j membrane either in loops or in enlargements, and they take a down- 

 I ward course between the gland- tubes, where they open into a net- 

 work of lacunar spaces. The branches which proceed from this 

 network on reaching the deep ends of the glands form a plexus, 



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