148 fHfi HUMAN BODY. 



testine, and these end in trunks which join the main lym- 

 phatic system. Finally, in each \illus, outside its lacteals 

 and beneath its muscular layer, is a close network of blood- 

 vessels. 



The Glands of the Small Intestine. Opening on the 

 surface of the small intestine between the bases of the villi 

 are small glands, the crypts of Lieberkiihn. Each is a 

 simple unbranched tube, lined by a single layer of cells. 



The Muscular Coat of the Small Intestine lying outside 

 the mucous coat, is composed of plain muscular tissue, dis- 

 posed in two layers: an inner circular, and an outer longi- 

 tudinal. By their combined and alternating contractions 

 they slowly force the digesting food along the tube. 



In the duodenum are found in addition minute glands, 

 the glands of Brunner, which lie outside the mucous 

 membrane, and send their ducts through it to open on its 

 inner surface. 



The Large Intestine (Fig. 49), forming the final portion 

 of the alimentary canal, is about 5 feet (1.5 meters) long, 

 and varies in diameter from 2% to 1J inches (6-4 centi- 

 meters). Anatomists describe it as consisting of the cc&cum 

 (cc) with its vermiform appendix, the colon (AC, TO, DC), 

 and the rectum (K). The small intestine does not open into 

 the end of the large but into its side, some distance from 

 its closed upper end; the ca3cum is that part of the large 

 intestine which extends beyond the communication. From 

 it projects the vermiform appendix, a narrow tube not 

 thicker than a cedar pencil, and about 4 inches (10 centi- 



Where do we find the crypts of Lieberkuhn? Describe them. 

 Where are the glands of Brunner? 



Give the dimensions of the large intestine. Of what parts is it 

 made up? How does the small intestine open into it? What is the 

 caecum? The vermiform appendix? Its size? 



