THE ABDOMINAL VISCEEA. 1421 



in contact with the anterior abdominal wall immediately above the lateral half of 

 the inguinal ligament. In "the normal condition it is completely surrounded by 

 peritoneum, and can, therefore, along with the vermiform process, be readily 

 delivered out of the abdomen. In chronic constipation, associated with intestinal 

 atony, the caecum is thin- walled, dilated, abnormally movable, and often prolapses 

 into the pelvis. 



The position of the ileo-caecal valve corresponds, on the surface of the body, to 

 the medial angle between the intertubercular and right lateral lines, while the 

 orifice of the vermiform process is one inch lower. It is to be noted that the lower 

 end of the ileum protrudes somewhat into the caecum, and that its circular muscular 

 fibres are prolonged into the flaps of the colic valve. Both of these anatomical 

 arrangements favour the occurrence of intussusception. In infants, other 

 predisposing causes are : (1) the relatively rapid enlargement of the lumen of the 

 large intestine as compared with the small ; (2) the greater mobility of the caecum ; 

 and (3) the frequent presence of a mesentery to the ascending colon. 



Vermiform Process. The vermiform process (O.T. vermiform appendix), 

 which springs from the postero-medial aspect of the caecum, one inch below the 

 ileo-caecal junction, is provided with a well-developed " meso-enteriole " derived from 

 the posterior aspect of the lowest part of the ileac mesentery. It is this portion of 

 the posterior layer of the mesentery which sometimes develops a band -like 

 thickening, which, by dragging upon the inferior end of the ileum, produces the kink 

 to which attention has been directed by Arbuthnot Lane. The artery of the 

 vermiform process is the only vessel which supplies the process ; it occupies the 

 free border of the meso-enteriole and gives off several branches which pass between 

 its two layers to reach the organ. In amputating the vermiform process the artery 

 is ligatured on the proximal side of its first branch in order to control the blood- 

 supply to the stump of the process. The fact that the vermiform process is supplied 

 by a single artery predisposes it to 

 gangrene should the vessel become 

 thrombosed, or should the circulation 

 in it be interfered with by kinking i LEO-COLIC ARTERY- 

 as a result of adhesions. 



,, . p .,, ILIAC BRANCH- 



Ihe vermnorm process will gener- 

 ally be found to pass either upwards 

 and medially, behind the lower end of 

 the ileum, or downwards and medially, 

 so as to overhang the external iliac 

 vessels at the superior aperture of 

 the pelvis minor ; less frequently it 

 ascends in the pouch behind the com- 

 mencement Of the ascending COlon. ARTERY OF THE 



A . p ,11 VERMIFORM 



When, as not infrequently happens, PROCESS 



i the retro-caecal fossa is prolonged up- 

 wards to form a pouch behind the 

 colon, the vermiform process almost 1105 ._ THE BLOOD . SDPPLY OF IHE C * CCM AND Vra . 

 invariably ascends into it, and should MIFORM PROCESS. 



1 it be diseased, it may give rise to a The miration gives a view of the c^cum from behind. 



I retro-caecal abscess. The abscess may The artery of the vermiform process, and the three 



: perforate the posterior wall Of the taenia coli springing from the .base of the process, should 



T ,, i be specially noted. (Modified by Birmingham from 



caecum, or it may ulcerate through jonnesco.) 



the posterior peritoneum ; in the 



latter case the suppuration may spread upwards, in the loose fatty sub-peritoneal 

 < tissue behind the colon, into the lumbar and perinephric regions; and it may 

 i reach even the under surface of the diaphragm and form a subphrenic abscess. 

 i When, in the course of its development, the caecum has failed to complete its 

 ! descent, the vermiform process may lie in the lumbar region in relation to the 

 ^ inferior pole of the kidney. When it dips downwards into the pelvis minor it may 

 : become adherent to the pelvic colon, the rectum, or the bladder, and in the female 

 I, to the uterine tube or the ovary. To find the vermiform process, the best plan 



