38 ORGANS OF DIGESTION. 



colon. The ileum runs into the left wall of the large intestine, 

 and continues its cellular and mucous coats into the corre- 

 sponding coats of the latter. The circular muscular fibres of 

 the large intestine separate to a certain degree to permit this 

 introduction, but their farther separation is restrained at each 

 commissure or corner of the lips, by a blending of the struc- 

 ture, aided by a few ligamentous fibres, designated as the re- 

 tinacula of Bauhin or of Morgagni; which, however, are fre- 

 quently not very distinct. This separation is also restrained 

 by the two longitudinal bands between which they are inserted, 

 one of which is at the posterior commissure, and the other 

 only a short distance off from the anterior. Thejips them- 

 selves, formed principally by the mucous membrane, approach 

 one another after the manner of the ship dock or canal gate; 

 the superior is somewhat broader than the inferior. Their 

 power, as well as their existence, depends entirely on the ten- 

 sion which is kept up by the natural connexions of the parts; 

 for a very slight dissection causes them to become almost ef- 

 faced, and instead of forming an elliptical transverse opening, 

 to be converted into a round patulous one. 



The Colon, properly speaking, has some regional distinctions 

 which are serviceable to accurate description. The right lum- 

 bar colon, which is bordered in front by the small intestine, and 

 behind, by the right kidney, extends from the ileo-colic valve, 

 to the margin of the false ribs of the corresponding side. The 

 transverse colon, bordered above by the stomach, and below 

 by the small intestine, goes from one hypochondriac region to 

 the other. It is generally found more distended than the other 

 portions. The left lumbar colon descends from the hypo- 

 chondriac region of the left side to the sigmoid flexure, being 

 bordered behind by the left kidney, and in front by the small 

 intestine. The sigmoid flexure, placed in the left iliac fossa, 

 forms a convolution, but is very indifferently described by the 

 term applied to it. It is occasionally very long and loose, and 

 terminates at the left sacro- iliac symphysis. It is not unfre- 

 quently found destitute of the partitions which prevail in other 

 parts. 



The Rectum begins at the left sacro-iliac symphysis, and 



