THE GREAT COLON 



425 



It IS somewhat difficult to get a correct idea of the cjEcal orifices. The caecum is sharply 

 cuijed here and a large fold projects into its interior, somewhat Uke a shelf, and separates the two 

 orifaces. The ileo-oa;cal orifice faces chiefly dorsally, while the csco-coHc orifice faces forward 

 into the caBcum. 



The Great Colon 

 The great colon (Colon crassum) begins at the caeco-colic orifice, and terminates 

 by joining the small colon behind the saccus caecus of the stomach. It is ten to 

 twelve feet (ca. 3 to 3.7 m.) long, and its average diameter (exclusive of its narrowest 

 part) is about eight to ten inches (ca. 20 to 25 cm.). Its capacity is more than 

 double that of the cajcum. When removed from the abdomen, it consists of two 

 parallel parts, which are connected by peritoneum and partially by areolax and 

 muscular tissue also. In situ it is folded so that it consists of four parts, which are 

 designated according to their position or numerically. The three bent connecting 

 parts are termed the flexures. The first part, the right ventral colon (Colon ventrale 

 dextrum), begins at the lesser curvature of the base of the ciEcum, about opposite 

 the ventral part of the last rib or intercostal space.i It forms an initial curve, the 



Origin of small colon 



Pelvic 

 flexure 



Diaphragmatic 



flexure 



-Sternal 

 flexure 



IleuiTt 

 Fig. 364. — Diagram op C^cum and Large Colon of Horse. 



convexity of which is directed upward and backward; this part is in contact with 

 the upper part of the right flank. It then passes downward and forward along the 

 right costal arch and then along the floor of the abdomen.^ Over the xiphoid 

 cartilage it bends sharply to the left and backward, forming the sternal flexure 

 (Flexura sternalis s. diaphragmatica ventralis). The second part, the left ventral 

 colon (Colon ventrale sinistrum), passes backward on the abdominal floor, to the left 

 of the first part and the caecum and, on reaching the pelvic inlet, bends sharply 

 dorsally and forward, forming the pelvic flexure (Flexura pelvina) . This is continued 

 by the third part, the left dorsal colon (Colon dorsale sinistrum), which passes 

 forward dorsal or lateral to the left ventral part, and on reaching the stomach, 

 diaphragm, and left lobe of the liver, turns to the right, forming the diaphragmatic 

 flexure (Flexura diaphragmatica dorsalis). The fourth part, the right dorsal colon 

 (Colon dorsale dextrum), passes backward dorsal to the first part, and on reaching 



^ The position of the origin of the great colon is variable, and one may easily get a wrong 

 impression on account of the peculiar arrangement of the bowel here. The colon usually presents 

 a saccular dilatation at the lesser curvature of the base of the caecum, which may be mistaken for 

 its origin. The real origin is a constricted part or neck anterior to the sacculation. Thus the 

 colon passes at first backward and then curves sharply downward and forward. Schmaltz has 

 proposed the name "vestibulum coli" for this sacculation. 



