LUMBAR PLEXUS. 325 



Lumbar Plexw. 



A communicating branch passes from the first to the 

 second ; others from the second to the third and from 

 the third to the fourth. The branches of the plexus are: 



1. The ilio-hypogastric and the ilio-inguinal, from 

 the first lumbar nerve. 



2. The genito-crural and a branch to the external 

 cutaneous and a large branch to the anterior crural from 

 the second lumbar nerve. 



3. The external cutaneous and anterior crural and a 

 branch to the obturator from the third lumbar nerve. 



4. The obturator, accessory obturator, a branch to 

 anterior crural, and a connecting branch to the fifth 

 lumbar from the fourth lumbar nerve. 



The plexus is imbedded deeply in the substance of 

 the psoas magnus muscle. 



1. The ilio-hypogastric, from first lumbar, runs along 

 the inner surface of the posterior wall of the abdominal 

 cavity, pierces the transversalis, and is distributed to the 

 integument of the gluteal and hypogastric regions. 



2. The ilio-inguinal, from the first lumbar below the 

 ilio-hypogastric, follows the inguinal canal and is dis- 

 tributed to the integument of pubes, scrotum, and groin. 



3. The genito-crural runs along the anterior surface 

 of the psoas magnus. It arises from the second lumbar. 

 It is distributed to the cremaster muscle in the male, and 

 the round ligament in the female. Another branch sup- 

 plies the skin along the inner part of the thigh. 



4. The external cutaneous, from the third lumbar, 

 receives a branch from the second lumbar. It runs 

 along the crest of the ilium and appears just below the 

 attachment of Poupart's ligament to the spine of the 

 ilium. It is distributed to the skin along the outer and 

 anterior part of the thigh. 



