322 



DISSECTION OF THE ABDOMEN. 



nearly 

 complete. 



Muscular 

 coat is 

 formed by a 



longitudinal 



and a cir- 

 cular layer. 



Show mu- 

 cous coat. 



at the attached side where the vessels enter : at this spot the peri- 

 toneum is reflected off to form the mesentery, and a space exists 

 between the serous layers like that at the borders of the stomach. 



The muscular coat is constructed of two sets of fibres, a superficial, 

 longitudinal, and a deep, circular. The fibres are pale in colour, and 

 are not striated. 



The longitudinal fibres form a thin covering, which is most marked 

 at the free border of the gut. 



The circular fibres are much more distinct than the others, and 

 give the chief strength to the muscular coat. These circular fibres 

 are best exposed by again turning the specimen and stripping off the 

 mucous membrane and the subjacent submucous tissue in one piece. 



Dissection. The long length of small intestine should now be 

 opened to show the mucous coat, but the gut should be cut along the 



Mucous 

 coat : 



thickness ; 

 folds ; 



villous 

 surface, 



and glands. 



Valvulse 

 conni- 

 ventes ; 



form ; 



size and 

 depth ; 



how formed 



FIG. 118. A. A PIECE OP Mucous 

 MEMBRANE ENLARGED, WITH ITS VILLI 

 AND TUBULES. PART OF A PETER'S 

 PATCH is ALSO REPRESENTED WITH 

 THE FOLLICLES (a), EACH HAVING A 

 RING OP TUBES AT THE CIRCUM- 

 FERENCE. 



B 



B. A "SOLITARY GLAND " 

 OF THE SMALL INTES- 

 TINE, ALSO ENLARGED, 

 COVERED BY VlLLI 



(BOEHM). 



line of attachment of the mesentery, so as to avoid Peyer's glands on 

 the opposite side. 



Mucous coat. The lining membrane is thicker and more vascular 

 at the beginning than at the ending of the small intestine. It is 

 marked by numerous prominent folds (valvulae conniventes) ; and 

 the surface of the membrane is covered with small processes (villi) 

 like the pile of velvet. Occupying the substance of the mucous 

 coat are numerous glands. 



The valvulce conniventes are permanent ridges of the mucous 

 membrane, which are arranged circularly in the intestine and 

 project into the cavity of the tube. Crescentic in form, they 

 extend round the intestine for half or two-thirds of its circum- 

 ference, and some end in bifurcated extremities. Larger and 

 smaller folds are met with, sometimes alternating ; and the larger 

 are about two inches long, and one-third of an inch in depth 

 towards the centre. Each is formed of a doubling of the mucous 

 membrane, which encloses a prolongation of the submucous coat, 

 with vessels between the layers. 



