THE COLON. . Y LOS! 
cecum certain fossee, of which the most interesting and important are—(a) the retro- 
cecal or retro-colic fossee ; (4) the ileo-ceecal fossa ; and (c) the ileo-colic fossa. 
The retro-colic fosse (Fig. 698, B) are only occasionally present, and are exposed by 
turning the cecum and adjacent part of the ileum upwards. Two forms, external and 
internal, are described; the first lies behind the outer part of the ascending colon, 
immediately above the cecum; the second behind its inner part. These fosse are 
specially interesting because, w hen present, they frequently lodge the vermiform pro- 
cess (see Fig. 698, B), a condition which is said to favour the production of appendicitis. 
Tleo-cecal Fossa and Fold.—If the appendix be drawn down, and the finger run 
towards the cecum, along the /ower border of the terminal part of the ileum, its point 
will generally run into a fossa situated in the angle between the ileum and czecum (Fig. 
698, A), which is ktiown as the ileo-cxecal fossa. The fold which bounds the fossa in front 
is the ileo-czecal fold (the ‘ bloodless fold of Treves”). It passes from the ileum to the 
front of the meso-appendix, which latter forms the posterior wall of the fossa. 
Tleo-colic Fold and Fossa.—Similarly, if the finger be run out along the wpper horder 
of the ileam towards the caecum, it will usually lodge in a smaller fossa, the ileo-colic, which 
coe ON 
\ VERMIFORM 
PROCESS 
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Le FOSSA 
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ANTERIOR \ 
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eas | —— 
\ RETRO-CAECAL FOSSA 
A B 
Fic. 698.—THE CmcaL FOLDS AND Foss@. 
In A, the exeum is viewed from the front ; the mesentery of the appendix is distinct, and is attached above 
to the under surface of the portion of the mesentery going to the end of the ileum. In B, the cecum 
is turned upwards to show a retro-czecal fossa, which lies behind it and the beginning of the ascending 
colon. 
is bounded in front by a small peritoneal process, the ileo-colic fold (Fig. 698, A), containing 
the anterior cecal artery. 
THE COLON. 
The ascending colon (colon ascendens) begins about the level of the inter- 
tubercular line, opposite the ileo-cxecal orifice, where it is continuous with the cecum. 
From this it runs upwards and somewhat backwards, with a slight concavity to 
the left, until it reaches the under surface of the liver, where it bends forwards 
and to the left, and passes into the hepatic flexure (Fig. 699). In its course it 
hes in the angle between the quadratus lumborum behind, and the more prominent 
psoas internally (Fig. 673). 
It is situated chiefly i in the right lumbar region, but it extends shghtly into 
the hypochondrium above ; and, although it usually begins about the level of the 
intertubercular line, still with a low position of the ceeum it will extend further 
down, and may occupy a considerable part of the ihac region. 
Its length is about 8 inches (20 em.), and it is wider ‘and much more prominent 
than the descending colon. It generally presents several minor curves or flexures, 
and it often has the appearance of being pushed into a space which is too short 
to accommodate it. 
Relations.—/n front, it is usually in coniact with the abdominal wall, but the 
small intestine frequently intervenes, particularly above (Fig. 670). To its inner 
