u 



INTESTINAL TUBE. 183 



DISSECTION III. 



INTESTINAL TUBE. 



The intestines must be washed before they can be examined, but 

 it should never be done until they are opened ; this may be accom- 

 plished by the scissors, or by a special instrument called an entero- 

 tome ; the section should be made along the line of attachment of 



e mesentery. 



The portion of the alimentary canal known as the INTES- 

 TINES, extends from the stomach to the anus, and is divided 

 into the small and large intestine. The small intestine ex- 

 tends from the pylorus to the caecum, the large from the 

 caecum to the anus ; they differ from each other in structure 

 as well as size, the first being of uniform calibre, and the 

 second much larger, and of a sacculated and irregular out- 

 line. 



The small intestine, about twenty feet in length, is arbi- 

 trarily divided into three portions, duodenum, jejunum, and 

 ileura. The duodenum is the first twelve inches beyond the 

 stomach; the jejunum is the first two fifths of the remain- 

 ing portion; the lower three fifths constitute the 'ileum, 

 which terminates in the caecum. 



The large intestine, or colon, about five feet in length, is 

 divided into the caecum, or caput coli, the ascending, trans- 

 verse, and descending colon, the sigmoid flexure, and the 

 rectum. Attached to the caecum is a small, tapering, tubular 

 appendage, a little bulbous at its occluded extremit}', from 

 three to six inches in length, and held in its place by a mesen- 

 tery proper to itself; it is usually tortuous, and about the 

 size of a pipe-stem ; it communicates with the interior of the 

 caecum through a small orifice, and is called the appendix 

 vermiformis cseci. Two or three longitudinal bands run the 

 whole length of the large intestine ; they are about half an 

 inch wide, and, being shorter than the canal itself, give to 

 its walls a sacculated character. 



To form a proper idea of the ileo-csecal valve, the caecum and a por- 

 tion of the ileum should be inflated and dried ; then cutting a window 

 in the side, its arrangement may be seen. 



The entrance of the ileum into the large pouch of the 

 caecum is protected by a valve, called the ileo-csecal, which 

 prevents regurgitation of its contents back into the small 



