1024 SUBGICAL ANATOMY OF HERNLZE. 



with the two layers of fascia (the infundibuliform aud spermatic fascisa) 

 between which those fibres are placed, are very thin in their natural state ; 

 but they may be readily distinguished in a surgical operation from the 

 investing superficial fascia, by their comparative density and the absence 

 of fat. 



In order to examine the peritoneum at the groin, it will be best to 

 divide that membrane with the abdominal muscles by two incisions drawn 

 from the umbilicus one to the hip-bone, the other to the pubes. The flap 

 thus formed being held somewhat outwards, and kept tense, a favourable 

 view will be obtained of the two fossae (inguinal fossw or pouches) with the 

 intervening crescentic fold. This fold is formed by the cord remaining 

 from the obliterated umbilical artery, which being shorter than the outer 

 surface of the serous sac, causes this to project inwards ; and as the length 

 of the cord differs in different cases, so likewise do the size and prominence 

 of the peritoneal fold vary accordingly. 



The lowest part of the outer fossa will be generally found opposite to 

 the entrance into the internal abdominal ring and the femoral ring, while 

 the inner one corresponds with the situation of the external abdominal 

 ring. But the cord representing the umbilical artery, which it has been 

 stated causes the projection of the serous membrane into a fold, does not 

 uniformly occupy the same position in all cases. Most frequently it is 

 separated by an interval from the epigastric artery, while in some cases it 

 is immediately behind that vessel. There is necessarily a corresponding 

 variation in the extent of the external peritoneal fossa. This fact will 

 find its practical application when the internal form of inguinal hernia is 

 under consideration. 



Between the peritoneum and the fascia lining the abdominal muscles is 

 a connecting layer of areolar structure named the subserous areolar mem- 

 brane. A considerable quantity of fat is in some cases found in this 

 membrane. 



The relative position of some of the parts above referred to may be 

 here conveniently stated, by means of measurements, made by Sir A. 

 Cooper, and adopted after examination by J. Cloquet. But, as the distance 

 between given parts varies in different cases, the following measurements 

 must be regarded only as a general average : 



MALE. FEMALE. 



From the symphysis of the pubes to the anterior ) K1 . , 



superior spine of the ilium . . .[^inches. ... 6 inches. 



From the same point to the spine of the pubes . . 1| ,, ... If ,, 

 ,, to the inner part of the external ) ni 1 



abdominal ring \ Ug " '" " 



,, to the inner edge of the internal [ 01 



abdominal ring \ 6 " 6 * 



,, to the epigastric artery on the inner ) ^a 01 



side of the internal abdominal ring . .\ * " '" s " 



From the preceding account of the structure of the abdominal wall at 

 the groin, it will be inferred that the defence against the protrusion of the 

 viscera from the cavity is here weaker than at other parts. The external 

 oblique muscle and the fascia transversalis are perforated, while the two 

 intervening muscles are thinner than elsewhere, and more or less defec- 

 tive. To this it must be added that the viscera are impelled towards 

 the same part of the abdomen by the contraction of the diaphragm and 

 the other abdominal muscles, in the production of efforts to overcome 



