306 SURGICAL APPLIED ANATOMY. [Chap. xvn. 



light, the lines of the valvulse conniventes can be well 

 seen. These folds are large and numerous in the 

 jejunum, but become small and scanty in the upper 

 ileum, and are wanting in the lower third of that 

 bowel. 



Injuries to the jejunum are more serious than 

 are those to the ileum, since an intestinal lesion 

 is (other things being equal) the more serious the 

 nearer it approaches to the stomach. The fatality of 

 umbilical hernise probably depends in part upon the 

 fact that the contained bowel is usually jejunum. \ Of 

 all the viscera the small intestines are the most exposed 

 to injury, and at the same time it must be noted that by 

 their elasticity, and by the ease with which their coils 

 slide over one another and so elude the effects of 

 pressure, they are the best adapted to meet such 

 injuries as contusions and the like. A minute punc- 

 tured wound of the small gut does not lead to extra- 

 vasation of contents. The muscular coat contracts 

 and closes the little opening. Thus, in excessive 

 tympanitis the bowels are often freely punctured in 

 many places with a fine capillary trochar, to allow the 

 gas to escape, without any evil resulting. A case 

 of intestinal obstruction of sixteen weeks' duration 

 is reported, in which the abdomen was punctured 

 150 times (Boston Med. Journ.). If the wound 

 be a little larger the loose mucous membrane be- 

 comes everted or protruded through the wound and 

 effectually plugs it. Gross found that a longitudinal 

 cut in the small bowel two and a half lines in length 

 was immediately reduced to a wound one and three- 

 quarter lines in length by muscular contraction, 

 and that the eversion of the mucous membrane in 

 addition to this contraction entirely sealed the 

 opening. 



Owing to the greater power of the circular layer 

 of muscle a longitudinal wound gapes more than a 



