100 TOPOGRAPHICAL ANATOMY OF THE 



colon, not very greatly wider than the small intestine with which its 

 coils are mixed, and possessed, like the small intestine, of a mesentery 

 that permits of a considerable degree of mobility. 



Great colon. — The disposition of the great colon is most easily 

 understood if it is regarded as having been twice doubled upon itself, so 

 that four lengths of intestine, united by three bends, have been pro- 

 duced. This will also account for the circumstance that the beginning 

 and the end of the tube are at no great distance from each other. 



Beginning at the lesser curvature of the caecum, the great colon 

 passes down the slope of the abdominal wall, on the right side of the 

 body, as the right ventral colon (colon ventrale dextrum), which ends 

 in the xiphoid region (on a level with the seventh or eighth rib) at the 

 ventral diaj)hragnnatic flexure (flexura diaphragmatica ventralis) that 

 carries the intestine over to the left side of the abdomen. From this 

 flexure the gut proceeds along the left side of the ventral part of the 

 abdomen — as the left ventral colon (colon ventrale sinistrum) — to the 

 entrance to the pelvis. At the pelvic inlet, and to the right of the 

 median plane, is the pelvic flexure (flexura pelvina), a bend in a dorsal 

 and forward direction, from which the tube again runs towards the 

 thorax. This part of the gut, the left dorsal colon (colon dorsale 

 sinistrum), lies dorsal and medial to the left ventral colon. A bend to 

 the right, the dorsal diajpliragmatic flexure (flexura diaphragmatica 

 dorsalis), on a level with the sixth or seventh rib, leads to the right 

 dorsal colon (colon dorsale dextrum) that passes towards the pelvis, 

 gradually increasing in diameter to assume finally the form of a bent, 

 blind, saccular tube. The termination of the great colon is marked by 

 a sudden narrowing of the gut, ventral and slightly to the right of the 

 left kidney. 



The peritoneal relations of the ctecum and great colon are con- 

 veniently observed at the present time. 



A triangular cceco-colic fold (plica csecocolica) connects the lesser 

 curvature of the dorsal sac and body of the c£ecum with the right 

 ventral colon. A similar but smaller ileo-coical fold (plica ileocsecalis), 

 produced by the ileum forsaking the border of the mesentery, passes 

 from the caecum to the terminal part of the ileum. 



The right ventral and right dorsal parts of the colon are closely 

 applied to each other and intimately united by peritoneum which forms 

 a common investment. The union of the left ventral and left dorsal 

 parts is also effected by peritoneum, but the association is much less 

 close ; for between the two tubes is a double layer of peritoneum that 

 gradually increases in breadth from the diaphragmatic to the pelvic 

 flexure. 



