ABDOMINAL CAVITY 



405 



divisions. Thus, the lower root of the genito-femoral springs 

 from the anterior division of the second lumbar nerve, whilst 

 the two roots of the lateral cutaneous nerve of the thigh 

 take origin from the posterior divisions of the second and 

 third lumbar trunks. 



The ilio-hypogastric nerve emerges from the lateral border of 

 the psoas, and crosses the quadratus lumborum obliquely. 

 At the crest of the ilium, it leaves the abdomen by piercing the 

 transversus abdominis muscle. Its further course has already 



Ilio-hypogastric 



Ilio-inguinal 



Genito-femoral 



\=r^r Femoral 



M. psoas major.-" 

 Obturator 



Femoral 



Twelfth rib 

 Last thoracic nerve 

 Ilio-hypogastric 

 Ilio-inguinal 



Genito-femoral 

 M. quadratus 

 lumborum 



Lateral 

 cutaneous 



Obturator 



Lumbo-sacral 

 trunk 



Lumbo-sacral trun 



FIG. 188. The Lumbar Plexus (semi-diagrammatic). 



been studied (p. 217). It gives off a lateral cutaneous branch 

 to the skin of the gluteal region, and an anterior cutaneous 

 branch to the skin over the lower part of the abdominal wall. 

 The ilio-inguinal nerve leaves the psoas major immediately 

 below the ilio-hypogastric nerve. It runs obliquely down- 

 wards and laterally over the quadratus lumborum and the 

 upper part of the iliacus, and disappears from view by pierc- 

 ing the transversus abdominis muscle, a short distance anterior 

 to the point where the ilio-hypogastric pierces that muscle. 

 It is distributed to the integument of the scrotum in the 

 male, and the labium majus in the female, and to the skin 

 ii 26 & 



