STOMACH AND INTESTINE, 



327 



numerous small and short vessels, the vasa 

 bi'cvia, 



The gasfro-epiploica smislra (i,Jfgs. 250,251 .) 

 leaves the trunk of the splenic artery close 

 to where this divides at the inner surface of 

 the spleen. It passes downwards, forwards, 

 and towards the right side, first lying for a 

 short distance in the gastro-splenic omentum, 

 and then entering between the layers of the 

 great omentum which is continuous with this 

 fold. It then runs along the lower border or 

 great curvature of the stomach, to anastomose 

 with the corresponding vessel on the right 

 side. Like it, it supplies branches to both 

 surfaces of the stomach. 



The vasa brcvia are numerous small branches 

 which come from the primary and secondary 

 divisions of the splenic artery, and run in the 

 gastro-splenic omentum to the cardiac pouch. 

 Here they break up and anastomose with 

 each other, as well as with the coronary and 

 left gastro-epiploic arteries. 



The veins of the stomach are the superior 

 pyloric, and the right and left gastro-epiploic. 



The vena pylorica superior receives and 

 continues a large vein, which corresponds to 

 the coronary artery, and takes a similar (but 

 reversed) course along the lesser curvature of 

 the stomach to the pylorus. It now passes 

 upwards for a little distance, before opening 

 into the vena portce (a, Jig. 281.) near its ter- 

 mination in the liver. In other instances, it 

 bends down to join the splenic vein. 



The vena gastro-epiploica dexfra corre- 

 sponds to its artery in the greater part of its 

 distribution. It usually ends by emptying 

 itself into the superior mesenteric vein, just 

 before this forms the vena portce by joining 

 with the splenic vein (e , jig. 281.). 



The venn gastro-epiploica sinistra also runs 

 with its artery, and joins either the splenic 

 vein, or one of its primary branches. 



All of the foregoing vessels are characterized 

 by the great freedom and frequency of their 

 inosculations in every stage of their course 

 from the aortic to the portal trunks. This con- 

 dition is especially well marked in the arteries. 

 And, as ordinarily injected, the latter ap- 

 pear to be both larger and more numerous 

 than the arteries distributed to an equal bulk 

 of most of the other structures of the body.* 



* Assuming this fact to be as true as it seems to 

 be, it becomes interesting to inquire what peculiari- 

 ties of the circulation may be presumed to be con- 

 nected with it. Other things being equal, the pas- 

 sage of a larger quantity of blood to and from an 

 organ may be fairly supposed to be associated with 

 a greater amount of that change which absorption 

 or secretion there impress upon this fluid. Again, 

 Volkmann's researches have shown that the anas- 

 tomosis of channels diminishes the resistance in 

 their interior; a diminution which, if not met 

 bj r any counteracting circumstance, would increase 

 the velocity of their contents. But the most plau- 

 sible conjecture that can at present be offered is, 

 that this increase in the number of these small ar- 

 teries, which have a distinctly muscular struc- 

 ture, and are plentifully supplied with nerves, has 

 reference to that efficient and sudden control of their 

 calibre which the varying exigencies of their capil- 

 lary circulation would seem to imply. 



Their tortuous course, and their loose con- 

 nection with the stomach, chiefly refer to the 

 distention of this organ. For as the stomach 

 expands between the laminae of peritoneum, 

 it gradually straightens these vessels, and 

 alters their position with respect to itself 

 and to each other. 



The distal branches of the arterial ami 

 venous trunks perforate the muscular coat 

 at different intervals, by twigs which unite 

 with each other in the loose submucous 

 areolar tissue, so as to form two broad 

 and somewhat flattened networks : one, 

 which is composed of small arteries, and 

 another, of veins. The vessels of the latter 

 plexus are, as usual, both larger and more 

 numerous than the corresponding arteries. 



Capillaries. The arterial branches which 

 leave the above sub-mucous network, to enter 

 the dense muscular layer of the matrix of the 

 stomach, divide here once or twice. And their 

 ultimate ramifications, which have a diameter 

 of about Ts'oo 1 ' 1 to Tg^th of an inch, pass 

 vertically upwards, along the sides of the tubes 

 to their upper apertures, where they form a 

 superficial network of capillaries. In passing 



Fig. 252. 



Flan of the vessels of the mucous membrane of the 

 stomach, as they would lie seen in a vertical section. 



a, arteries from the plexus occupying the sub- 

 mucous areolar tissue; l>, superficial plexus of capil- 

 laries occupying the ridges of the mucous mem- 

 brane; c, veins passing downwards between the 

 gastric'tubes ; d, capillaries between and around the 

 tubes ; e, plexus of arteries and veins occupying the 

 submucous areolar tissue. 



upwards, they also give off other capillaries ; 

 which surround the tubes, at all parts of 

 their height, with a second and deeper net- 

 work. The meshes of this latter plexus are 

 somewhat oblong, but less decidedly so than 

 those of the capillary network of striped 

 muscle; and are about -j-^th to T ^th of an 

 inch in size. The capillaries which compose 

 them are, on an average, little more than 

 5oVo tn of an incli in diameter. The more 

 superficial network is contrasted with this 

 deeper one, not only in the fact that its capil- 

 laries are about double the above diameter (or 



Y 4 



