THE CECUM 



12G9 



The Interior of the Cecum. Corresponding to the surface sacculations are seen 

 the pouch-like depressions (Jiaustra) bounded by the semilunar folds (^plicae semi- 

 lunares coli) (Fig. 1035), corresponding to the surface constrictions which mark 

 off the saccules. The interior of the cecum is continued into the colon above, 

 and the orifice of the ileum and of the appendix open into it. These orifices, 

 guarded respectively by the ileocecal valve and by the valve of Gerlach, are described 

 on pages 1300 and 1302. 



Pericecal Folds and Fossae. See page 1267, and Figs. 991 and 992. 



TYPE III. 



TYPE II. 



90% 



TYPE IV. 



TYPE I (Treves). 



2% 



FIG. 1036. The four types of cecum. 



The Vermiform Appendix (processus vermiformis} (Figs. 1038 and 1044). The 

 vermiform appendix is found only in man, the higher apes, and the wombat, 

 although in certain rodents a somewhat similar arrangement exists. In carnivo- 

 rous animals the cecum is very slightly developed; in herbivorous animals (with 

 a simple stomach) it is, as a rule, extremely large. It has been suggested that the 

 vermiform process in man is the degenerated remains of the herbivorous cecum, 

 which has been replaced by the carnivorous form. The vermiform appendix is 

 a long, narrow, worm-shaped, musculomembranous tube, which starts from w r hat 

 was originally the apex of the cecum. After development has advanced the vermi- 

 form appendix comes off, as a rule, from the inner side of the posterior wall of the 

 cecum, below and behind the termination of the ileum. This origin usually cor- 

 responds to McBurney's point on the abdominal wall, midway between the umbilicus 

 and the anterior superior iliac spine, and which is the usual seat of the greatest 



