LUMBAR PLEXUS. 



579 



forming the anterior crural and obturator nerves. The fourth nerve completes the 

 formation of the anterior crural, and the obturator, furnishes part of the accessory 

 obturator, and gives off' a communicating branch to the fifth lumbar. 

 The branches of the lumbar plexus are the 



Ilio-hypogastric. 

 Ilio-inguinal. 

 Genito-crural. 

 External cutaneous. 



Obturator. 



Accessory obturator. 

 Anterior crural. 





These branches may be divided into two groups, according to their mode of 

 distribution. One group, including the ilio-hypogastric, ilio-inguinal, and part 

 of the genito-crural nerves, supplies the lower part of the parietes of the abdomen ; 

 the other group, which includes the remaining nerves, supplies the forepart of the 

 thigh and inner side of the leg. 



Fig. 290. The Lumbar Plexus and its Branches. 



The ILIO-HYPOGASTRIC NERVE (superior musculo-cutaneous) arises from the first 

 lumbar nerve. It pierces the outer border of the Psoas muscle at its upper part, 

 and crosses obliquely in front of the Quadratus lumborum to the crest of the 

 ilium. It then perforates the Transversalis muscle at its back part, and divides 

 between it and the Internal oblique into two branches, iliac and hypogastric. 



