1218 



THE DIGESTIVE SYSTEM. 



The lymph, vessels of the caecum and vermiform process arise mainly from networks in the 

 mucous and serous coats. 



The first of these networks communicates with a lymph sinus which is found at the base of 

 the lymph nodules in the process, and the vessels from it pierce the muscular coats, and pass 

 in company with the blood-vessels. They are connected with mucous lymph glands found near 

 the ileo-caecal junction, especially on the posterior and medial aspect, in the angle between the 

 ileum and colon. 



Small isolated glands may be found lying in close contact with the medial part of the caecum, 

 on its anterior and posterior aspects. From these glands, the lymph stream is directed upwards 

 and medially towards the cceliac and lumbar glands. The lymph vessels of the vermiform 

 process may also communicate with the lymph nodes in the iliac fossa, and also, it has been 

 stated, with the lymph vessels of the right ovary. 



Caecal Folds and Fossae. The peritoneum in the neighbourhood of the caecum 

 forms certain fossae, of which the most interesting and important are (a) the fossa 

 caecalis ; (b) the recessus ileocaecalis inferior ; (c) the recessus ileocaecalis superior ; and 

 (d) the recessus retrocsecalis. 



(a) The fossa caecalis (Fig. 956, B) is only occasionally present, and can be exposed by 

 turning the caecum and adjacent part of the ileum upwards. It is a fossa in the 



VERMIEORM 

 PROCESS 



ETRO-CAECAL FOSSA 

 B 



FIG. 956. THE C^ECAL FOLDS AND FOSS.E. 



In A, the caecum is viewed from the front ; the mesentery of the vermiform process is distinct, and is attached 

 above to the inferior surface of the portion of the mesentery going to the end of the ileum. In B, the 

 caecum is turned upwards to show a retro-caecal fossa, which lies behind it and behind the beginning 

 of the ascending colon. 



parietal peritoneum on the posterior abdominal wall, open above, in which the lower end 

 of the ceecum occasionally lies. It is produced by the plica ccecalis, a peritoneal fold which 

 passes from the surface of the iliacus to the right lateral aspect of the caecum. Two forms, 

 lateral and medial, are described ; the first lies behind the lateral part of the ascending 

 colon, immediately above the caecum ; the second behind its medial part. These fossae 

 are specially interesting because, when present, they frequently lodge the vermiform pro- 

 cess (see Fig. 956, B), a condition which is said to favour the production of appendicitis. 



(b and c) Recessus Ileocaecales and Plica Ileocsecalis. If the vermiform process is 

 drawn down, and the finger run towards the caecum, along the inferior border of the terminal 

 part of the ileum, its point will generally run into a fossa situated in the angle between 

 the ileum and caecum (Fig. 956, A), which is known as the recessus ileoccecalis inferior. 

 The fold which bounds the fossa in front is the plica ileoccecalis (O.T. the "bloodless 

 fold of Treves "). It passes from the ileum to the front of the mesentery of the 

 vermiform process, which forms the posterior wall of the fossa. 



The plica ileocaecalis contains some unstriped muscle fibres continuous with the 

 longitudinal muscle coat of the caecum, and some fat especially at its free margin. 



The recessus ileocaecalis inferior is bounded above by the lower end of the ileum, to 

 the right by the caecum, in front by the plica ileocaecalis, behind by the root of the 

 mesenteriolum of the processus vermiformis, while it is open to the left or medially. 



Similarly, if the finger is run out along the superior border of the ileum towards the 

 caecum, it will usually lodge in a smaller fossa, the recessus ileoccecalis superior, which is 



