462 



DISSECTION OF THE ABDOMEN. 



Fig. 155. 



verse colon, are processes of peritoneum containing fat the appendices 

 epiplo'icae. 



Dissection. For the purpose of examining the large intestine the 

 student should cut off and blow up the caecum, with part of the ileum 



entering it; he should prepare in a similar 

 way a piece of the transverse colon, and a 

 piece of the sigmoid flexure (about four inches 

 of each). The areolar tissue and the fat are 

 to be removed with care from each, after it 

 has been inflated. 



The CAECUM, or the head of the colon (fig. 

 155, a) (caput caecum coli) is the rounded 

 part of the large intestine which projects, in 

 the form of a pouch, below the junction of 

 the ileum with it. It measures about two 

 inches and a half in length, and though 

 gradually narrowing iriferiorly, the caecum is 

 the widest part of the colon hence the name 

 caput coli. At its inner side it is joined by 

 the small intestine (ft) ; and still lower there 

 is a small worm-like projection (c) the ver- 

 miform appendix. 



Appendix vermiformis (fig. 155, e). This 

 little convoluted projection is attached to the 

 lower and hinder part of the caecum, of which 

 it was a continuation, at one period, in the 

 embryo. From three to six inches in length, 

 the appendix is rather larger than a goose- 

 quill, and is connected to the inner part of 

 the caecum by a fold of peritoneum. It is 

 hollow, and has an aperture of communica- 

 tion with the intestine (d). In structure it 

 resembles the rest of the colon. 



Dissection. To examine the interior of the 

 caecum, and the valve between it and the 

 small intestine, the specimen should be dried, 

 and the following cuts should be made into 

 it: One oval piece is to be taken from the 

 ileum near its termination ; another from the 

 side of the caecum, opposite the entrance of the small intestine. 



lleo-ccecal valve (fig. 155). This valve is situate at the entrance of the 

 ileum into the caecum. It is composed of two pieces, each with a different 

 inclination, which project into the interior of the caecum, and bound a 

 narrow, nearly transverse aperture of communication between the two 

 differently-sized portions of the alimentary canal. 



The upper piece of the valve, ileo-colic (e) projects horizontally into 

 the large intestine, opposite the junction of the ileum with the colon. And 

 the lower piece, ileo-ccecal (/), which is the larger of the two, has a ver- 

 tical direction between the ileum and the caecum. At each extremity of 

 the opening the pieces of the valve are blended together; and the result- 

 ing prominence (</) extends transversely on each side of the intestine, 

 forming the/rtzna or retinacula of the valve. 



INTERIOR OF A CAECUM OKI ED AND 



LAID OPEN. 



. Caecum. 



b. Small intestine 



c. Vermiform appendix, and d, its 



aperture. 



e. Ilio-colic piece of the valve at 

 the junction of the small in- 

 testine. 



/. Ilio-csecal piece of the valve. 



g. Retinaculum of the valve on 

 each side. 



