1178 



SPLANCHNOLOGY- 



part becomes greatly increased, so that at birth there is a narrow tube, the vermi- 

 form process, hanging from a conical projection, the cecum. This is the infantile 

 form, and as it persists throughout life in about 2 per cent, of cases, it is regarded 

 by Treves as the first of his four types of human ceca. The cecum is conical and 

 the appendix rises from its apex. The three longitudinal bands start from the 

 appendix and are equidistant from each other. In the second type, the conical 

 cecum has become quadrate by the growing out of a saccule on either side of the 

 anterior longitudinal band. These saccules are of equal size, and the appendix 

 arises from between them, instead of from the apex of a cone. This type is found 

 in about 3 per cent, of cases. The third type is the normal type of man. Here 

 the two saccules, which in the second type were uniform, have grown at unequal 

 rates: the right with greater rapidity than the left. In consequence of this an 

 apparently new apex has been formed by the growing downward of the right sac- 

 cule, and the original apex, with the appendix attached, is pushed over to the left 



Terminal part of ileocolic artery 



Cecal branches 



Heal branches 



Appcndicular 

 artery 



FIG. 1073. The cecum and vermiform process, with their arteries. 



toward the ileocolic junction. The three longitudinal bands still start from the 

 base of the vermiform process, but they are now no longer equidistant from each 

 other, because the right saccule has grown between the anterior and postero- 

 lateral bands, pushing them over to the left. This type occurs in about 90 per 

 cent, of cases. The fourth type is merely an exaggerated condition of the third; 

 the right saccule is still larger, and at the same time the left saccule has become 

 atrophied, so that the original apex of the cecum, with the vermiform process, is 

 close to the ileocolic junction, and the anterior band courses medial ward to the 

 same situation. This type is present in about 4 per cent, of cases. 



The Vermiform Process or Appendix (processes vermiformis) (Fig. 1073) is a long, 

 narrow, worm-shaped tube, which starts from what was originally the apex of the 

 cecum, and may pass in one of several directions: upward behind the cecum; to 

 the left behind the ileum and mesentery; or downward into the lesser pelvis. It 

 varies from 2 to 20 cm. in length, its average being about 8.3 cm. It is retained 

 in position by a fold of peritoneum (mesenteriole), derived from the left leaf of 



