Fascice Lining the Abdomen. 177 



middle layer is attached to the tips of the transverse pro- 

 cesses of the lumbar vertebrae and, at the outer edge of the 

 quadratus lumborum, this division of the lumbar fascia 

 blends with the anterior layer, while, on the outer side of 

 the erector spinae muscle, it receives the posterior layer. 

 This middle layer forms the posterior aponeurosis of the 

 transversalis muscle. 



Muscles forming the posterior wall of the 

 abdomen. The quadratus lumborum muscle arises 

 from the ilio-lumbar ligament and from the crest of the 

 ilium for about two inches, and is inserted into the lower 

 border of the last rib for about half its length, and into 

 the tips of the transverse processes of the four upper 

 vertebrae. Another portion of the muscle, arising from 

 the tips of these processes, is inserted into the lower mar- 

 gin of this rib also. 



The psoas magnus arises from the sides of the bases 

 and lower borders of the transverse processes of the lum- 

 bar vertebrae and from the sides of the bodies and the in- 

 tervertebral substances of the last dorsal and all the lum- 

 bar vertebrae and is inserted into the lesser trochanter of 

 the femur. 



The psoas parvus, from the sides of the last dorsal and 

 first lumbar vertebrae, into the iliac fascia and the pectin- 

 eal line, together with the iliacus from the iliac fossa, 

 from the margin of the crest of the ilium, from the ilio- 

 lumbar ligament, and from the anterior spine of the ilium, 

 into the outer side of the psoas magnus muscle and into 

 the oblique line extending from the lesser trochanter to 

 the linea aspera, complete the muscular protection of the 

 abdomen. 



The Actions of these muscles. The quadratus lum- 

 borum steadies the last rib when the diaphragm contracts 

 and thus assists inspiration. It also, by depressing the' 



