406 ABDOMEN 



of the medial aspect of the proximal part of the thigh (pp. 

 217 and Vol. L, p. 231). 



The genito -femoral nerve (O.T. genito-crural nerve) is 

 directed forwards through the psoas major, and appears upon 

 its anterior aspect, where it ends by dividing into a lumbo- 

 inguinal and an external spermatic branch. The external 

 spermatic branch proceeds downwards and medially. It 

 crosses the lower end of the external iliac artery obliquely, 

 and reaches the abdominal inguinal ring. There it comes 

 into relation with the constituents of the spermatic cord, and, 

 leaving the abdomen, is distributed to the cremaster muscle. 

 In the female it is a small branch, and it ends in the round 

 ligament of the uterus and the labium pudendi. The 

 lumbo-inguinal branch runs downwards along the lateral side 

 of the external iliac artery, and, after crossing the deep 

 circumflex iliac artery, it passes behind the inguinal ligament. 

 Then it descends along the side of the femoral artery and 

 after piercing the iliac part of the fascia lata it supplies the 

 skin over a portion of the femoral triangle. 



The lateral cutaneous nerve of the thigh (O.T. external cutaneous 

 nerve) emerges from the lateral border of the psoas major about 

 its middle, and descends obliquely across the iliacus muscle, 

 behind the fascia iliaca, to the anterior superior spine of the 

 ilium. At that point it leaves the abdomen by passing behind 

 the inguinal ligament. It supplies the skin upon the lateral 

 and anterior aspect of the thigh. 



The femoral nerve (O.T. anterior crural nerve) is the 

 largest branch of the plexus. It runs downwards in the 

 interval between the psoas major and iliacus, and passes out 

 of the abdomen behind the inguinal ligament. It gives a 

 branch to the iliacus muscle. 



The obturator nerve emerges from the medial border of 

 the psoas major, where that muscle reaches the brim of the 

 pelvis minor. Then it passes forwards and downwards upon 

 the inner surface of the wall of the pelvis minor, a short 

 way below the ilio-pectineal line of the hip bone. At the 

 upper part of the obturator foramen it joins the artery of the 

 same name, passes out from the pelvis minor and enters the 

 thigh. 



A small nerve, called the accessory obturator, is occasion- 

 ally found. It may spring either from the obturator or from 

 the third and fourth lumbar nerves. It proceeds downwards 



