Chap, xvi.] LUMBAR REGION. 321 



tissue in the lumbar region is very extensive, and is a 

 favourite locality for chronic abscess. The looseness 

 and extent of tue tissue also permit of large extrava- 

 sations of blood. It is in the muscles and fascia 

 along the spine in this region that the rheumatic 

 affection known as lumbago has its seat. 



Between the last rib and the iliac crest is stretched 

 the dense fascia lumborum, the posterior aponeurosis 

 of the transversalis muscle. It is pierced near the rib 

 by the last intercostal artery and nerve and near the 

 ilium by the ilio-hypogastric nerve and its accompany- 

 ing artery. It is along these structures that an abscess 

 may possibly find its way through the fascia in certain 

 cases. The fascia divides behind into three layers, to 

 enclose in definite spaces the quadratus and erector 

 epinse muscles. Within these spaces or compartments 

 suppuration may be for some time limited. A lumbar 

 abscess commencing in some adjacent part, as in the 

 spine or in the loose tissue around the kidneys, 

 usually spreads backwards by piercing the fascia 

 lumborum or the quadratus muscle. It then finds its 

 way through the internal oblique, and appears on the 

 surface between the external oblique and latissimus 

 dorsi muscles, and at the outer border of the erector 

 spinae. It should be noted that the quadratus muscle 

 is very thin, and offers little resistance to protrusions 

 from within, while a great part of the muscle is firmly 

 supported behind by the erector spinae. 



The author's operation for caries of the 

 lumbar vertebrae. The lumbar vertebrae, and, 

 possibly, the last dorsal, may be reached by an incision 

 through the loin. A vertical cut is made along the 

 outer edge of the erector spinse muscle. The fibres of 

 that muscle having been drawn aside, the middle 

 layer of the fascia lumborum is incised, and the quad- 

 rated lumborum is exposed. This muscle is divided 

 vertically, and then the front of the vertebra may be 

 v 4 



