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ANATOMY AND PHYSIOLOGY OP 



extending on to the hepatic flexure of the 

 colon, after it has surrounded the first-named 

 gut. The next portion of intestine is at- 

 tached to the spine transversely to the long 

 axis of the body ; winding round the mes- 

 entery to the left of the aorta, it gets at- 

 tached to the gastric flexure of the colon, 

 and here it proceeds, under the name of 

 jejunum, along the free borders of the 

 mesentery. 



As to the shape of the duodenum, from 

 the pylorus to the right of the porta, we 

 find its dimensions so very great as to have 

 suggested to the ancients the similitude be- 

 tween it and the stomach, of which they 

 regarded it in some degree as an analogue, 

 as testified by the appellation " Ventriculus 

 Succenturiatus," given to it by them. Fur- 

 ther from the pylorus, we find it constricts 

 and assumes a certain caliber, which it 

 maintains till it loses its name for that of 

 jejunum. 



With reference to the relations of the 

 duodenum, it may be stated that they ad- 

 mit of detail on account of the fixedness 

 of that portion of the gut, an attribute with 

 which it is endowed in contradistinction 

 to the jejunum and ileum. In the first 

 portion of its course, i. e., from the py- 

 lorus to the posterior part of the right 

 lobe of the liver, the duodenum by its 

 upper surface is in contact with the con- 

 cave surface of the latter organ, crossing 

 the vena portee, near w^hich it is pierced by 

 the billiary and pancreatic ducts, which 

 enter it at about five or six inches from the 

 pylorus, forming an acute angle with each 

 other. The inferior surface of the duo- 

 denum rests on the transverse colon, and 

 its superior margin is in close contact with 

 the anterior part of the head of the pan- 

 creas. 



Round to the right, the duodenum is in 

 contact with the hepatic flexure of the 

 colon, right and Spigalian lobes of the liver, 

 as well as the right kidney. To reach the 

 spine it has to cross the direction of the 

 right flexure of the colon, getting behind 

 the mesentery and gastric flexure of the 



colon, where it is connected with the left 

 kidney. 



Alluding next to the general anatomical 

 facts as applied to the jejunum, so caUed 

 on account of its usual vacuity after death, 

 the limit between it and the ileum is de- 

 fined by imagining the small intestine, with 

 the exception of the duodenum, divided 

 into five equal portions, of which the first 

 two take the name of jejunum, whilst the 

 last three-fifths receive that of ileum. 



The jejunum is suspended superiorly 

 from the spine by an extensive fold of per- 

 itoneum, termed mesentery, which serves 

 also as a medium for the passage of the 

 mesenteric arteries, veins and nerves, as well 

 as for chyliferous vessels, to take their 

 course towards the receptaculum chylo, sit- 

 uated to the left of the aorta. 



The width of the jejunum is far from 

 being uniform, it being more constricted at 

 some points than at others: its narrowest 

 part is that which is contiguous to the 

 ileum. 



The ileum is the terminating portion of 

 the small intestine, so called from the tor- 

 tuous course it takes, emptying itself into 

 the large intestine at the junction of the 

 CEecum and colon, by an orifice provided 

 with a valve. 



The first portion of the ileum is simply 

 attached by mesentery to the spine ; but, 

 in addition to this, in the last ^art of its 

 course, the gut is connected with the csBum 

 by a fold of peritoneum, which is not large 

 enough to prevent them deviating more 

 than an acute angle from each other. 



The ileum is, on the whole, the narrow- 

 est portion of the small intestine, but the 

 thickest in its coats. 



Having now especially to describe the 

 structure of the small intestine, it may be 

 taken as a whole, merely alluding to local 

 peculiarities. 



This portion of the alimentary canal has 

 four coats, to be described in the same 

 order by those of the stomach, i. e. peri- 

 toneal, muscular, cellular, and internal 

 mucus. 



