1304 



THE ORGANS OF DIGESTION 



resistance makes the appendix a ready prey to bacteria. Among causes which lessen resistance 

 are fecal concretions, twists of the mesoappendix cutting off the blood supply, bruises inflicted 

 by the Psoas muscle (Byron Robinson), blocking of the outlet of the appendix by catarrhal 

 exudate, concretions, proliferated lymphoid tissue, or adhesions. Appendicitis may arise by the 



appendix becoming twisted, owing to 

 the shortness of its mesentery, in con- 

 sequence of distention of the cecum. 

 As the result of inflammation, its 

 blood supply, which is mainly through 

 one large artery running in the meso- 

 appendix, becomes interfered with. 

 Again, in rarer cases, the inflamma- 

 tion is set up by the impaction of a 

 solid mass of feces or a foreign body 

 in the appendix. The inflammation 

 may result in ulceration and perforation, 

 or in gangrene of the appendix the ap- 

 pendix may be blocked and full of pus, 

 or abscess may form outside of it (appen- 

 difular abscess). These conditions re- 

 quire prompt operative interference, 

 and in cases of recurrent attacks of 

 appendicitis it is advisable to remove 

 this diverticulum between the attacks. 

 The cecum and appendix may be 

 implicated in cases of strangulated 

 hernia, giving rise to serious symptoms 

 of obstruction. An obstruction in the 



distal part of the large bowel causes distention, particularly of the cecum, which sometimes 

 assumes enormous dimensions, and has been known to rupture, causing fatal peritonitis. 



ANTERIOR 



T/EN IA 



EDGE OF 



CECUM 



SUPERIOR 



SEGMENT 



POSTERIOR 



T/ENIA' 



ORIFICE OF 



APPENDIX 



INTERNAL 

 T>ENIA 



FRENULUM 

 ORIFICE OF 

 VALVE 



INFERIOR 

 SEGMENT 



FIG. 1045. Ileocecal valve. (Sappey.) 



The Colon. 



The colon is divided into four parts the ascending, transverse, and descending 

 colon and the sigmoid flexure. 



The ascending colon (colon ascendens) is smaller than the cecum, with which 

 it is continuous. It passes upward, from its commencement at the cecum, oppo- 

 site the ileocecal valve, to the under surface of the right lobe of the liver, on the 

 right of the gall-bladder, where it is lodged in a shallow depression on the liver, 

 the impressio colica; here it bends abruptly forward and inward to the left, forming 

 the hepatic flexure (flexura coli dextra). It is retained in contact with the pos- 

 terior wall of the abdomen by the peritoneum, which covers its anterior surface 

 and sides, its posterior surface being connected by loose areolar tissue with the 

 Quadratus lumborum muscle, and with the front of the lower and outer part 

 of the right kidney (Fig. 1046). Sometimes the peritoneum almost completely 

 invests it, and forms a distinct but short mesocolon 1 (p. 1251). It is in relation, 

 in front, with the convolutions of the ileum and the abdominal parietes. 



The transverse colon (colon transversum) (Fig. 983), the longest and most 

 movable part of the large intestine, passes transversely from the right hypo- 

 chondriac region across the abdomen, opposite the confines of the epigastric 

 and umbilical zones, into the left hypochondriac region, where it curves downward 

 beneath the lower end of the spleen, forming the splenic flexure (flexura coli 

 sinistra). In its course the transverse colon describes an arch, the concavity of 



* Treves states that after a careful examination of one hundred subjects, he found that in fifty-two there was 

 neither an ascending nor a descending mesocolon. In twenty-two there was a descending mesocolon, but no 

 trace of a corresponding fold on the other side. In fourteen subjects there was a mesocolon to both the ascend- 

 ing and the descending segments of the bowel; while in the remaining twelve there was an ascending mesocolon, 

 but no corresponding fold on the left side. It follows, therefore, that in performing lumbar colostomy a meso- 

 colon may be expected on the left side in 36 per cent, of all cases, and on the right in 26 per cent. (The Anatomy 

 of the Intestinal Canal and Peritoneum in Man, 1885, p. 55.) 



