370 



DISSECTION OF THE ABDOMEN. 



parts cover- 

 ing it on 

 two sides, 



beneath it ; 



use to bend 

 hip-joint. 



Quadratus 

 lumborum : 



origin ; 



insertion ; 



is contained 

 in a sheath ; 



use of both 

 muscles, 



of one. 



Fascia of the 

 quadratus. 



Iliac fascia 

 covers 

 ilio-psoas ; 



attachments 

 below, 



and abov< 



femur ; and a few have a separate attachment to the femur below 

 the small trochanter (fig. 61, p. 158). 



Above Poupart's ligament the muscle is covered by the iliac fascia ; 

 and over the right iliacus are placed the caecum and ascending colon, 

 over the left, the sigmoid flexure : beneath it is the hip-bone. The 

 inner margin is overlapped by the psoas ; and the anterior crural 

 nerve lies between the two. The relations of the united psoas and 

 iliacus below Poupart's ligament are given with the dissection of the 

 thigh (p. 167). 



Action. The iliacus raises the femur with the psoas when the 

 limb is moveable, and bends forwards the pelvis when the limb is 

 fixed. 



The psoas and iliacus may be regarded as two heads of one muscle 

 the ILIO-PSOAS. 



The QDADRATUS LUMBORUM (fig. 138, G) is a short, flattened 

 muscle between the pelvis and the last rib. About two inches wide 

 below, it arises from the ilio-lumbar ligament, and from the iliac 

 crest behind, and for an inch outside that band (fig. 139) ; it generally 

 receives in addition two or three slips from the transverse processes 

 of the lower lumbar vertebrae. The fibres ascend to be inserted by 

 distinct fleshy and tendinous slips into the apices of the transverse 

 processes of the upper four lumbar vertebrae, and into the lower 

 border of the last rib for a variable distance. 



This muscle is encased in a sheath derived from the fascia 

 lumborum. Crossing the surface are branches of the lumbar plexus, 

 together with the last dorsal nerve and its vessels. Behind the 

 quadratus is the erector spinse muscle. 



Action. Both muscles keep straight the spine (one muscle 

 antagonising the other) ; and by fixing the last rib they aid in the 

 more complete contraction of the diaphragm. 



One muscle will incline laterally the lumbar region of the spine 

 to the same side, and depress the last rib. 



Fascia of the quadratus. Covering the surface of the quadratus is 

 a thin membrane, derived from the hinder aponeurosis of the trans- 

 versalis abdominis (anterior layer of the fascia lumborum), which 

 passes in front of the quadratus to be fixed to the tips and borders 

 of the lumbar transverse processes, to the ilio-lumbar ligament below, 

 and to the last rib above. A thickened band of this fascia forms the 

 external arched ligament, to which the diaphragm is connected. 



ILIAC FASCIA. This fascia covers the double flexor of the hip- 

 joint, and is fixed to the bone on each side of the muscle. The 

 membrane is strongest opposite the pelvis, where it is attached 

 to the iliac crest on the outer side, and to the brim of the cavity on 

 the inner side : it receives a strong accession from the tendon of the 

 psoas parvus when that muscle is present. Over the upper part of 

 the psoas it becomes thin, and is fixed on the one side to the lumbar 

 vertebrae ; while on ihe other it is blended with the fascia over the 

 quadratus ; and above, it joins the internal arched ligament of the 

 diaphragm. Its disposition at Poupart's ligament, and the part 



