Chap, xvi.] THE ABDOMINAL PARIETES. 271 



of the reetus may be much stretched, since they bear 

 the brunt of the distending force. The direction of 

 the fibres also renders them liable to be torn in the 

 opisthotonos, or extreme arching of the back, of 

 tetanus. Portions of the muscle have also been 

 ruptured by muscular violence. 



The lateral muscles of the front abdominal wall 

 are separated from one another by layers of loose 

 connective tissue. These extensive layers favour 

 the spread of interstitial abscesses of the abdominal 

 parietes. Such abscesses will be guided in their 

 course by the attachments of the muscles between 

 which they spread, and will be limited by the semi- 

 lunar lines in front, by the lower parts of the ribs and 

 their cartilages above, by Poupart's ligament and the 

 iliac crest below, and by the edge of the erector 

 spinse behind. The same remark applies to hsemorr- 

 hagic or emphysematous collections between these 

 muscles. 



Between the abdominal parietes and the perito- 

 neum is a layer of loose connective tissue, the subserous 

 connective tissue. The looseness of this layer greatly 

 favours the spread of abscess, to the progress of which 

 it offers little resistance. Such an abscess may spread 

 from the viscera, especially from those that have an 

 imperfect peritoneal covering, as, for example, the 

 kidney, the vertical parts of the colon, etc. The 

 laxity of this tissue is of great service in certain 

 surgical procedures. Thus the external and common 

 iliac arteries can be reached by an incision made some 

 way to the outer side of the vessels and without 

 opening the peritoneum. That membrane having 

 been exposed in the lateral wound, the artery is 

 reached by working a way with the finger through 

 the subperitoneal tissue, and by actually stripping 

 the serous membrane from its attachments. This 

 condition of the subserous layer also favours that 



