796 



A MANUAL OF ANATOMY 



Structure of the Vermifdrm Appendix. — The vermiform appendix 

 is entirely covered by peritoneum, which forms a more or less 

 complete meso- appendix or appendicular mesentery. It has a 

 muscular coat, composed of an external longitudinal and internal 

 circular layer, both of which completely surroimd it. The 



Circular Muscular Fibres 

 Longitudinal Muscular Fibres 



Peritoneal Coat 



Submucosa 



Mucosa with Lieberkiihn's 

 Crypts 



Fig. 342. 



eso-appendix 



Lymphoid Nodules 



-Transverse Section of the Vermiform Appendix 

 (highly magnified). 



submucous coat contains, in great abundance, lymphoid nodules 

 (solitary glands) of large size, and the mucous coat contains a few 

 lymphoid nodules, as well as a few crypts of Tieberkiihn. The 

 base of the appendix is situated at a point on an average rather 

 more than i inch below the ileo-caecal valve according to Treves. 

 The opening by which the appendix communicates with the caecum 

 is occasionally guarded by a fold of mucous membrane, which is 

 known as the valve of Gerlach. 



The vermiform appendix is usually regarded as the remains of the herbi- 

 vorous caecum. It is also looked upon as an appendage of the lymphoid 

 system, and as such it would belong to the class of structures represented by 

 Peyer's patches, namely, lymphoid organs. In its typical form it is peculiar 

 to man, the higher apes, and the marsupial wombat. In certain rodents, 

 however — e.g., the rabbit and hare — the verv lirui cnmcious ca'cum shows an 

 approach to a vermiform appendix at its lown i \tri mily. 



