1 666 



HUMAN ANATOMY. 



along the proximal half or even the whole length of the appendix, one is free, and 

 the other two are attached to the left side of the mesentery and to the caecum 

 respectively. These latter are not readily distinguished from each other; hence the 

 triangular effect. The artery of the appendix enters the fold on the back of the 

 caecum, and runs at first from 5 mm. to i cm. distant from its free edge, which 

 gradually approaches it. Although the fold may terminate before reaching the end 

 of the appendix, it does not follow that the whole of the latter is not enclosed in peri- 

 toneum, since under normal circumstances it always must be. The course, shape, 

 and size of the meso-appendix are very irregular. It is almost invariably so short 

 that the proximal half of the appendix is thrown into coils. We have seen this fold 

 attached to the right side of the mesentery, as well as not attached to it at all. 

 Sometimes it runs upward along the posterior part of the left side of the colon, so 

 that the appendix is vertical ; at other times it is attached to the floor of the iliac 

 fossa ; and very rarely it is wanting. In the female adult a secondary fold can very 

 often, but by no means always, be traced from the meso-appendix to the broad 

 ligament. This fold is probably due to the persistence of one which in the foetus 

 often connects the appendix or caecum with the early ovary and the oviduct. The 

 lymph-node which the meso-appendix is said to contain we have seldom found. 



It happens frequently that, from 

 Fig. 14x7. pathological causes by which ad- 



hesions have changed the perito- 

 neal relations, the appendix lies 

 behind the peritoneum. Fergu- 

 son found it so 77 times in 200. 



Pericaecal Fossae. — An 

 indefinite number of fossae or 

 pouches, all more or less variable, 

 are to be found about the caecum. 

 The two following are usually 

 demonstrable, although not so 

 constant as held by some authors 

 The superior ileo-csecal 

 fossa ^ (Fig- 1414J is roofed in 

 by a peritoneal duplicature, the 

 superior ileo-ccecal fold, which, 

 starting from the right surface of 

 the mesentery, curves over the 

 end of the ileum from behind forward. The attached border, in which the ileo-colic 

 artery lies, runs along the colon just where it joins the ileum, and is usually con- 

 tinued forward down onto the front of the caecum for a short distance. The pouch 

 between this fold above and the end of the ileum below opens to the left, but if the 

 ileum be distended, the free edge of the fold is so closely applied to it that the fossa 

 is easily overlooked. The depth of the fossa may reach 3 cm. It is most distinct 

 in infants and frequendy obliterated in middle life, although careful examination often 

 reveals a small fold and recess that may be overlooked. Berry found this fossa 

 absent in 12 of 100 cases, all of the 12 being over forty years. 



The inferior ileo-caecal fossa ^ C^ig. 141 7 J i= less constant and much more 

 complicated than the preceding. Its practical importance is greater, since it may 

 contain the appendix. To display it the ileum must be drawn upward and the 

 appendix downward and to the right ; the caecum may or may not require to be 

 displaced to the right or inverted. This fossa is situated in the entering angle 

 formed by the end of the ileum joining the caecum, and is bounded on the right by 

 the first part of the appendix. The meso-appendix shuts it in behind, and in front 

 it is covered by the inferior ileo-caecal fold. ^ The latter, which usually joins the 



* There is much to be said in favor of the term ileo-colic, since the pocket lies at the angle 

 of the ileum and colon. It, however, so frequently extends downward to the front of the caecum 

 that the more usual nomenclature is here adopted. 



* Known also as the ileo-colic fossa, the ileo-appendicular fossa, etc. 



* This is the "bloodless" fold of Treves or the ileo-appendicular fold of Jonnesco. 



Ileum, turned up 



Inferior ileo-caecal 

 fold 



Inferior ileo- 

 caecal fossa 



Meso-appendix 



Caecum from inner side and below. 



