THE CyECUM. 



1663 



about half below and half above the level of the anterior superior iliac spine. Some- 

 times, owing to the shortness of the ascending colon, the caecum remains in the 

 foetal position under the liver, or it may be arrested at any part of its descent. It 

 not rarely hangs down into the pelvis, and when the lower part of the mesentery is 

 long, particularly if the lower part of the ascending colon be not attached to the 

 posterior wall, it may be very freely movable. In cases of mesenterium commune 

 there seems to be no anatomical reason why it should not be anywhere. The 

 caecum is sometimes turned up over the lower part of the ascending colon, but we 

 cannot agree with Curschmann's ' statement that this is not rare. In these cases the 

 appendix rises from near the highest point of the caecum. We have seen the caecum 

 in the umbilical region with two vertical coils of small intestine occupying the right 

 flank. 



Structure. — The description of the structure of the large intestine already 

 given (page 1657J applies in general to the caecum. Its mucous membrane, like 



Fig. 1415. 



Lumen of csecum 









Lymph-nodules 



Circular 

 muscle 



l.^ ^4&, \^ ^ 



Avy^ \,.-5^f.i\ — .Lieberkuhn s glands 



Groups of fat-cells 



lucous coat 



Submucous tissue 



Longitudinal section through junction of appendix with caecum. X 12. 



that of the rest of the large intestine, has no villi. This change occurs near the 

 margin of each segment of the ileo-caecal valve, the villi gradually diminishing and 

 finally disappearing before the free edge of the folds is reached (Langer). The 

 bands of longitudinal muscular fibres always end at the base of the appendix, but 

 the precise manner of their termination is uncertain. According to Struthers,^ each 

 band bifurcates as it approaches the appendix, and the divisions, meeting those of 

 the others, form a ring around a weak spot close about it. According to Toldt,^ the 

 ring is formed by the circular layer. The arrangement is not always clear, but we 

 incline to think the latter the more common. The coats of the caecum are all found 

 in the appendix. The lumen of the latter is small, except near the entrance, and 

 the walls may be in contact. The lymph-nodules of the appendix are exceedingly 

 numerous and large, in places fusing into masses of considerable size, which en- 



' Deutsches Archiv fiir Klin. Med., Bd. liii., 1894. 



^ Edinburgh Medical Journal, 1893. 



^ Sitzungsber. Acad. Wissen., Wien, Bd. ciii., 1894. 



