376 PRACTICAL ANATOMY. 



placed opposite to the attachment of the mesentery. The 

 patches are ahout three-fourths inch wide, one and one- 

 half inches long, but vary both in size and shape ; they 

 are surrounded by villi and mucous crypts. 



THE LARGE INTESTINE. 



The large intestine begins in the right inguinal region 

 and terminates at the anus. It is about five feet long. 

 Throughout the whole of its extent it is sacculated and 

 covered by columnar epithelium. It is divided into the 

 ascending, transverse, and descending colon and the rec- 

 tum. The ascending colon begins as a blind pouch, the 

 caecum, which is the largest part of the colon. It is 

 situated in the right inguinal region and is held in posi- 

 tion by the peritoneum, which, as a rule, covers the 

 anterior surface and sides of the caecum. Attached to 

 its lower posterior part is the appendix vermiformis, a 

 rudimentary caecum. It is about four inches long, about 

 as thick as a pencil, and often entirely invested by peri- 

 toneum. The ileum enters the caecum at its inner side, 

 the opening being designated the ileo-caecal valve. These 

 valves are placed horizontally, and they are formed by 

 the reduplication of the mucous membrane of the caecum 

 and muscular fibres. When these are cut the valve dis- 

 appears, and the opening gapes widely and is funnel- 

 shaped. The iliac surface of the valve is covered with 

 villi. The upper portion of the ascending colon passes 

 upward to the under surface of the liver. Its sides and 

 anterior surface are covered by peritoneum. Beneath the 

 liver it bends at right angles and becomes the transverse 

 colon, and is entirely surrounded by peritoneum, which 

 holds it to the posterior wall of the abdomen by the 

 meso-colon. In the left hypochondriac region beneath 

 the spleen it bends abruptly downward, becoming the 



