THE LARGE INTESTINE. 413 



The veins of the appendix and the caecum end in the ileocolic vein, which joins 

 the superior mesenteric vein and helps to form the portal vein. Hence infection is 

 carried by the blood stream from the appendix and caecum directly to the liver. 



Position of the Appendix. The position and direction of the appendix have 

 been variously described and much discussed. This has arisen from the fact that it 

 is so curled, curved, and twisted on itself that it is impossible to say that it points in 

 any definite direction, and that, being so mobile, it may be found in almost any posi- 

 tion, swinging around with its point of attachment to the caecum as the axis. We 

 agree with Cunningham when he says that it runs generally in one of three direc- 

 tions: (i) over the brim into (or towards) the pelvis; (2) upward behind the caecum; 

 (3) upward and inward toward the spleen. As he says, each of these has been con- 

 sidered the normal position by one or more observers. It is evident that, as 



Retroco 



Colic branch 



Ileocolic artery 

 Anterior ileocascal 



- branch 



Superior ileocsecal fold 



- Heal branch 

 Superior ileocwcal fossa 



Posterior ileoca;cai 

 branch 



Inferior ileocsecal fold 

 Inferior ileocaecal fossa 

 Appendicular artery 



Recurrent branch 

 Meso-appendix 



Retrocolic fold' 



Retrocolic fossa 

 FIG. 424. The appendix and ileocaecal region, showing the folds, fossa?, and arteries. 



the appendix comes off close to the ileum, this is its most fixed and constant point. 

 In certain cases the caecum retains its high fetal position and then the appendix will 

 be higher than usual. If the appendix is long and straight, its tip may reach to or 

 beyond the median line; it may lie in contact with the rectum, ovary, tube, or blad- 

 der; it may lie low down close to Poupart's ligament or curved upward behind the 

 colon, reaching in front of the kidney and nearly or quite to the liver. When retro- 

 ciecal it lies on the quadratus lumborum; when lower it may lie on the iliacus or 

 psoas muscle. If it goes over the brim of the pelvis it lies on the external iliac 

 artery. The external iliac vein is below and to the inner side and is largely pro- 

 tected from injury in operating by the stronger and tougher artery. 



Caecal Folds and Fossae. There are three folds and three fossae formed by 

 the peritoneum in the neighborhood of the caecum. 



i. The superior ileoc&cal (ileocolic} fold runs from the upper surface of the 

 mesentery just above the ileum to the upper anterior surface of the caecum. In it 

 runs the ileoc&cal (anterior} artery. Beneath it, with its opening toward the left, is 

 the superior ilcoc&cal fossa (Fig. 424). 



