196 SURGICAL ANATOMY OF THE PELVIS. 



erector spinse is covered in by the aponeurosis of the 

 latissimus dorsi. 



In spinal caries of the lumbar region, the pus, by 

 perforating the quadratus lumborum, between the last 

 rib and crest of ilium, passes backwards, and being 

 bound down by the various fascial laminae just men- 

 tioned, forms a tumor, usually flat, broad, and slightly 

 elevated ; occasionally the pus finds its way between the 

 abdominal muscles and points above Poupart's ligament. 



Although the psoas muscles essentially belong to the 

 lumbar region, yet psoas abscesses do not necessarily 

 arise in them, the course taken by the pus being in a 

 great measure governed by the fascial investment they 

 obtain there ; this investment is that of the fascia iliaca, 

 which, as regards the muscles, is attached above to the 

 ligamenta arcuata interna, internally to the sacrum, 

 being continued over the muscles to the crural arches, 

 beneath which the pus gravitates, and ultimately points 

 external to the femoral vessels. Sometimes it passes 

 through the sacro-sciatic notch to the nates. 



The relation of the nerves to the spinal column, 

 emerging as they do either through the intervertebral 

 spaces or sacral foramina, readily accounts for the course 

 taken by the pus in these abscesses. 



Iliac abscess is a collection of matter either in the 

 cellular tissue, between the iliac fascia and peritoneum, 

 or between the fascia iliaca and iliacus muscle, and points 

 above Poupart's ligament, near the anterior superior 

 spinous process of the ilium. 



SUKGICAL ANATOMY OF THE PELVIS. 



Those portions of the true pelvis and its contents 

 which come within the province of the surgeon are more 



