276 THE ABDOMEN AND PELVIS 



and, in this case, the oblique incision need not extend so high 

 as the angle between the sacro-spinalis and the last rib. The 

 fascia transversalis may be incised as soon as it is reached, and 

 the surgeon then works medially, stripping the peritoneum off 

 the posterior abdominal wall, until the anterior surface of the 

 psoas major is recognised. On the other hand, the fascia 

 transversalis may be left intact and the surgeon works medially, 

 stripping it and the fascia iliaca forwards as a continuous sheet. 

 When the psoas major is reached, the fascia is carefully torn 

 through with the finger nail. Whatever method is employed 

 the ureter will be found adherent to the posterior aspect of the 

 peritoneum, and its presence there can readily be detected if the 

 pulp of the finger is turned forwards and lightly drawn across 

 its course. When it has been separated from the peritoneum, 

 the ureter can be brought up to the surface and incised to permit 

 of exploration with probes or the removal of a calculus. Owing 

 to its rich blood-supply (p. 354), incisions in the ureter soon heal, 

 and, for the same reason, complete isolation of the duct is not 

 followed by damage from sloughing. 



THE ABDOMINAL CAVITY. 



The differences which exist between the living subject and 

 the dissecting-room cadaver are probably more marked in the 

 abdomen than in any other part of the body. The action of 

 the preservatives used not only renders firm those organs which 

 are pliant in life, such as the liver and the spleen, but also 

 produces shrinkage of the abdominal contents and retraction 

 of the anterior wall. In addition the living peritoneum possesses 

 a certain amount of mobility on the extra-peritoneal fat, and 

 can stretch or be stretched without tearing, but both these 

 characteristic features disappear after death. As a result, the 

 positions of viscera relative to the vertebral column, as found 

 in the cadaver preserved and dissected in the horizontal position, 

 differ somewhat from those which they occupy in the living 

 subject, more especially when the body is in the erect posture. 



With the exception of the retroperitoneal viscera, which are 

 practically fixed, the positions of viscera relative to the surface 

 vary within wide limits. The influences which govern these varia- 

 tions are (i) posture, (2) the personal factor, (3) the physiological, 

 and (4) the pathological condition at the time of examination. 



