chap. xvi.] THE ABDOMINAL PARIETES. 277 



very nerves that supply the parietes.* These 

 nerves go to the great plexuses that provide the 

 nerve supply for the abdominal viscera, to the great 

 solar plexus, and to some of those more or less 

 directly derived from it. Without some such expla- 

 nation it is difficult to understand why the sympa- 

 thetic supply of the abdominal organs should be 

 derived from a nerve cord half way up in the thorax, 

 when that very cord extends into the abdomen itself, 

 and could provide a much more direct supply. This 

 nerve relationship is illustrated in disease in many 

 ways. Thus, in acute peritonitis and in laceration of 

 certain of the viscera the abdominal muscles become 

 rigidly contracted, so as to insure as complete rest as 

 possible to the injured parts. In acute peritonitis 

 the belly is very hard, the respirations are purely 

 thoracic, and so entirely do the cutaneous portions of 

 these nerves enter into the situation, that the patient 

 is often unable to tolerate even the most trifling 

 pressure upon his abdomen. 



Congenital deformities of the abdomen. 

 In the foetus the intestinal canal is cut off from the 

 yolk sac by the gradual growth of the ventral plates 

 and their ultimate union in the middle line. This 

 union occurs latest at the umbilicus, and when, 

 complete the abdominal cavity is entirely enclosed. 

 In some cases of imperfect development the anterior 

 abdominal wall is more or less entirely absent, and 

 the viscera are either entirely uncovered or protected 

 only by a scanty membrane. This condition is usually 

 associated with other deformities, which are incon- 

 sistent with any but very brief existence. In many 



* Beck (Phil. Trans., 1846) and others state that the great 

 splanchnic nerve is in connection with the upper as well as with 

 the lower thoracic ganglia, and such a connection would place the 

 abdominal viscera in relation with a still larger number of respi- 

 ratory muscles, and would further support the interest of those 

 viscera in the respiratory movements generally. 



