THE JEJUNO-ILEUM. 



1651 



Fig. 



1404. 



denum the line of the mesentery is usually on the right of the gut ; with a duodenum 

 that crosses the aorta the line is across the third part. The lower end of the mesen- 

 tery is determined by the degree of adhesion .of the right mesocolon to the abdomi- 

 nal wall. It rarely stops short of the sacro-iliac joint, but it may be continued 

 farther into the right iliac fossa. 



The free or intestinal border of the mesentery is some 6 m. or about 20 ft. long. 

 In the middle the distance between the borders is from 20—22.5 cm. (8—9 in.). 

 Near its origin, in the first six inches of the intestine, the mesentery has reached a 

 breadth of from 12-15 cm. (5-6 in.). At the lower end its breadth is more uncer- 

 tain, being usually slight, only from 2.5-5 cm. for the last six inches. It increases 

 with age, presumably concurrently with the increase of girth. The mesentery con- 

 tains vessels and nerves as well as lymphatic nodes between its folds; these struc- 

 tures may lie in a considerable mass of fat, adding to the thickness, which is much 

 greater, on account of the size and number of the vessels, in the upper part than in 

 the lower. The larger lymph-nodes 

 and the fat accumulate chiefly near the 

 spinal border, where the mesentery 

 may be very thick and heavy, while 

 the part near the intestine, except in 

 the case of excessive fatty accumula- 

 tion, is always thin and yielding. It 

 is evident that the mesentery with an 

 attached border of only 15 cm, (6 in.) 

 and a free one of 6 m. (20 ft.) must be 

 very much folded ; and further, that 

 while the intestinal border must pre- 

 sent a vast number of totally irregular 

 and transitory folds, changing with 

 the movements of the gut, the heavier 

 and more fixed part of the mesentery 

 near the root must present certain chief 

 folds the position of which is tolerably 

 stable. 



Henke ^ has shown that if the hand 

 be introduced among the coils of intes- 

 tines in the line of the left psoas muscle 

 and carried upward, it enters the con- 

 cavity of a horseshoe- shaped fold of the 

 mesentery, and that the intestines easily 

 fall apart to either side. . The coils on 

 the left are in the main transverse and 

 those to the right chiefly vertical. This 

 plan, although sometimes obscure, is often beautifully clear, especially in infants. 

 Weinberg,^ from studies on the new-born infant, has carried the plan into further 

 details. He finds that the upper two-fifths of the intestine are arranged in trans- 

 verse folds in the upper left part of the abdomen ; the middle fifth lies in the left 

 iliac region without definite arrangement ; the last two-fifths are in the median 

 part and in the right iliac region, disposed in the main vertically. Still, cases 

 occur at all ages in which the plan is obscure. Mall ' has traced the plan of the 

 intestines throughout development, and incidentally confirms Weinberg's state- 

 ments. The following account of the normal arrangement in the adult is essentially 

 according to his researches. The gut is to be conceived as arranged in spiral coils 

 travelling from the left hypochondriac region to the right iliac fossa, successive coils 

 being in the main parallel. Starting from the duodenum, there are two transverse 

 folds in the left hypochondrium, followed by a long fold that goes across the body 

 and back. Some less distinctly transverse folds occupy the left iliac fossa. The 



' Arch, fiir Anat. und Entwicklng., 1891. 



" Internat. Monatsschrift fiir Anat. und Phys., Bd. xiii., 1S96. 



° Arch, fiir Anat. und Entwicklng., 1897. Supplement Bd. 



Typical disposition of folds of mesentery shown after 

 removal of jejuno-ileum. i, end of duodenum ; 2, 3, 4, jeju- 

 num ; s, ileum ; 6, termination of ileum into large intestine. 

 (Mall.) 



