328 



THE ABDOMEN AND PELVIS 



the diverticulum and the vermiform process (appendix) occupy 

 the same segment in the spinal medulla, the reflex sensory 

 symptoms are very similar, and consequently inflammation of 

 the diverticulum may easily be mistaken for appendicitis. In 

 the cystic variety (Fig. 103, v) only the middle part of the 

 intra-embryonic portion of the duct remains patent. 



Differences between the Large and Small Intestine. 

 The large intestine differs from the small intestine in its outward 

 appearance in several particulars, (i) The longitudinal muscular 

 coat does not surround the large intestine completely. Instead, 

 it forms three narrow bands, termed the tcenicz coli, which are 

 visible through the serous coat. (2) The large intestine is 

 sacculated. (3) Appendices epiploicce are found on the large 



I II III IV V 



FIG. 103. Diagrams to illustrate different degrees of Persistence of 



the Vitello-intestinal Duct. 



I, II and III show different stages in the production of a hernia of the dorsal wall of 

 the small intestine through a patent vitello-intestinal duct and umbilicus. 



IV shows a patch of granulations at the umbilicus and a partially obliterated vitello- 

 intestinal duct. 



V shows incomplete obliteration of the vitello-intestinal duct with the formation of a 

 small cyst near the umbilicus. 



The heavy black lines represent the small intestine, and the shaded area represents 

 the anterior abdominal wall. The dotted line represents the peritoneum. 



intestine ; they consist of small peritoneal sacs filled with fat. 

 (4) The wall of the large intestine is thinner than the wall of the 

 small intestine. This difference is referable to the longitudinal 

 muscular and the mucous coats. 



These features of the large intestine are subject to a good 

 deal of variation. 



The Colic (Ileo-Caecal) Valve is placed at the junction of 

 the ileum with the large intestine, and it serves to demarcate 

 the caecum, which lies below it, from the ascending colon, which 

 lies above it. The position of the valve may be indicated on 

 the surface at the point of intersection of the intertubercular 

 and the right lateral planes. 



