1214 



THE DIGESTIVE SYSTEM. 



The interior of the caecum corresponds in general appearance to that of 

 the large intestine ; but it presents two special features on the posterior part of 

 its medial wall, namely, the ileo-csecal orifice, guarded by the valvula coli (O.T. ileo- 

 csecal valve), and below that the small opening of the processus vermiformis, both 



of which call for further notice. 



Valvula Coli (O.T. Ileo-caecal 

 Valve). Where the ileum enters the 

 large intestine, the end of the small gut 

 is, as it were, thrust through the wall of 

 the large bowel, carrying with it certain 

 layers of that wall, which project into 

 the csecum in the form of two folds, 

 lying respectively above and below its 

 orifice, and constituting the two seg- 

 ments of the valve (Fig. 952). The 

 condition may be compared to a partial 

 inversion or telescoping of the small 

 into the large intestine : it must be 

 added that the peritoneum and longi- 

 tudinal muscular fibres of the bowel 

 take no part in this infolding ; on the 

 contrary, they are stretched tightly 

 across the crease produced on the ex- 

 terior by the inversion, and thus serve 

 to preserve the fold and the formation 

 of the valve. 



As seen from the interior, in speci- 

 mens which have been distended and 

 dried (Fig. 953), the valve is made up 

 of two crescentic segments a superior, 

 labium superius, in a more or less 

 horizontal plane, forming the superior 

 margin of the aperture ; and an inferior, 

 labium inferius, which is larger, placed in 

 an oblique plane, and sloping upwards 

 and inwards (i.e., towards the cavity of 

 the csecum). Between the two seg- 

 ments is situated the slit-shaped open- 

 ing, which runs in an almost antero- 

 posterior direction, with a rounded an- 

 terior and a pointed posterior extremity 

 (Fig. 952). At each end of the orifice 

 the two segments of the valve meet, 

 ^^-^^^^tgZLZZ unite, and are then prolonged around 

 formalin. the wall of the cavity as two prominent 



The hardening was not so complete in the case of the folds the frenula Valvulse COli. It is 



highest of the three valves represented. In each thought that when the C83CUni is dis- 

 tended, and its circumference thereby 

 increased, these frenula are put on the 



stretch, and, pulling upon the two segments of the valve, they bring them into 



apposition, and effect the closure of the orifice. 



The position of the valvula coli, in the average condition, may be indicated 



on the surface of the body by the point of intersection of the intertubercular and 



vertical lateral lines. A point 1 to 1J inches (2*5 to 3'7 cm.) lower down would 



correspond to the orifice of the vermiform process. 



In bodies hardened in situ with formalin, the valve and orifice present an entirely different 

 appearance (see Fig. 952, in which three different forms of hardened valves are shown), suggesting, 

 much more closely than in the dried state, the appearance of telescoping or inversion mentioned 

 above. In them also the two segments of the valve are much thicker and shorter, but they can 





Orifice 



Lower 

 segment 



Orifice of 



vermiform 



process 



Orifice f 



