964 THE ORGANS OF DIGESTION 



An oblique l((i/er, continuous with the circular fibres of the oesophagus. They 

 pass tt) the left of the a'sophagus towards the great curvature. They unite finally 

 with the circular fibres (fig. 560 ). 



The submacouti coat is made up of areolar tissue, in which tlu" ])l()()d-vessels 

 break up. 



The mvcou--< or internal coat is pink in colour and soft to the touch, and when 

 the stomach is not distended has a rugose appearance. It is covered Avith colunmar 

 epithelium, and with a lens shows the openings of numerous glands. A thin layer 

 of muscular tissue — the musadaris mucosx — supports the mucous memlDrane ex- 

 ternally. The mucous membrane is thickest in the pyloric area and thinnest over 

 the great cnl-clc-mc. In the stomachs of young persons the surface of the stomach 

 may l)c studded by little elevations due to local accumulations of lymphoid tissue. 



Nerves. — The nerves of the stomach are the right and left pneumogastric, the 

 right nerve passing over the posterior surface, and the left over the anterior. The 

 organ is also connected Avith the sympathetic SA'stem l:>y means of the solar j^lexus. 



Blood-supply. — The stomach receives its blood-supply from many branches. 

 From the cieliac axis there is the gastric artery, which runs along the lesser curve 

 from left to right, anastomosing with the pyloric branch of the hepatic. Along the 

 greater curve run the right and left gastro-epiploic arteries, anastomosing at the 

 middle of the border, the left being a branch of the splenic, the right a branch of 

 the hepatic through the gastro-duodenal artery. The stomach also receives 

 l)ranches from the splenic (vasa brevia) at the fundus. 



The blood of the stomach is returned into the portal vein. The coronary vein 

 and pyloric vein open separately into the portal vein; the right gastro-epiploic vein 

 opens into the superior mesenteric, the left into the splenic. 



Lymphatics. — There is a set of glands lying along the greater and the lesser 

 curvatures, and others at the pyloric and cardiac ends. These are entered l)y 

 lymphatic vessels beginning in the mucous membrane. 



THE INTESTINES 



THE SMALL INTESTINE 



The small intestine is that part of the intestinal canal w-hich lies between the 

 pylorus and the ileo-ciccal valve. It is conveniently divided into three portions: 

 the duodenum, jejunum, and ileum. It is of the average length in the adult 

 male (between the ages of twenty and fifty) of tw^enty-two feet six inches. In the 

 female it is longer, the average length being twenty-three feet four inches. The 

 length is inde|)endent, in the adult at least, of age, height, or weight. The length 

 may vary in the male from thirty-one feet ten inches to fifteen feet six inches. In 

 the female, from twenty-nine feet four inches to nineteen feet ten inches. 



With the exception of the duodenum, the small intestine lies for the most part 

 inside the more fixed portions of the large intestine (figs. 565, 578). It is also, 

 with the exce]ition of the duodenum, connected to the posterior abdominal wall by 

 a process of ])eritoneum, the meMntery. This broad membrane is seen to extend 

 from above downwards, and from left to right from the duodenum above totheileo- 

 ca?cal valve below, enclosing tlic jejunum and ileum along the wliole of their ex- 

 tent (figs. 561, 568, and 599). 



The duodenum — the first portion of the small intestine — is, unlike the otl)er 

 parts of that bowel, very definite in position and extent. It is that part which is 

 not contained by the mesentery. It is formed from the end of the embryonic fore- 

 gut, and its peculiar position V)ehind the transverse colon is due to the rotation from 

 left to right of the intestine in the foetus (page 995). It is the most fixed as well 

 as the widest part of the small intestine. It measures one and a half to two inches 



