THE ABDOMINAL WALLS 273 



the peri-nephric fascia and in front of the quadratus lumborum 

 (Fig. 83), and so reach the anterior surface of the lumbo-dorsal 

 fascia near the origin of the trans versus abdominis (trans versalis). 

 At this point the peri-nephric and trans versalis fasciae become 

 continuous, but they are both adherent to the origin of the 

 muscle and check further spread in a lateral direction. The 

 pus may perforate the lumbo-dorsal fascia and enter the upper 

 lumbar triangle, from which it may spread to the lumbar 

 triangle (of Petit) (p. 269). 



(2) The pus may follow the direction of the psoas major and 

 enter the thigh behind the inguinal ligament. In its course it 

 may infect and erode the sacro-iliac joint, or it may spread to the 

 bursa which separates the tendon of the muscle from the hip-joint. 

 When this bursa communicates with the joint, the latter also may 

 become infected. This condition is referred to again on p. 423. 



(3) The pus may pass downwards at first and then, spreading 

 laterally, gain the iliac fossa where it lies behind the fascia iliaca. 

 Its presence in this situation may be recognised on abdominal 

 palpation. At the iliac crest both the fascia iliaca and fascia 

 transversalis are bound down to the bone, but, should the abscess 

 increase in size, their attachments are not strong enough to limit 

 it to the iliac fossa, and it may come towards .the surface near 

 the anterior superior iliac spine. In these cases it is advisable 

 to evacuate the pus, and the muscles may be divided by a grid- 

 iron incision. The transversalis fascia is not incised, but is 

 separated from the trans versus muscle until the abscess is reached. 



(4) The pus may occasionally pass backwards, following the 

 course of the dorsal branch of a lumbar artery. It usually 

 passes medial to the sacro-spinalis and points near the posterior 

 median line, or it may spread upwards and downwards within 

 the sheath of the muscle (Fig. 83). 



The Approach to the Kidney from behind. In 

 nephropexy and other operations which do not necessitate the 

 exposure of the ureter, a vertical incision along the lateral border 

 of the sacro-spinalis (erector spince) gives good access. After 

 the skin and fasciae have been divided, the oblique lower fibres 

 of the latissimus dorsi are cut across in the line of the incision, 

 exposing the lumbo-dorsal fascia (lumbar aponeurosis), which 

 is also incised vertically. In the upper part of the wound, the 

 posterior layer of the peri-nephric fascia is now exposed, but, 

 below, the lateral margin of the quadratus lumborum, which 

 crosses the wound obliquely (p. 270), must be divided together 



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