Lumbar Plexus 



357 



caries of that bone inflammatory pressure upon the posterior root of 

 the nerve is manifested by definite peripheral neuralgias the patient 

 complaining of pains in the front of the belly, in each groin, or over 

 the hips. 



The second nerve sends down a branch to the third, and divides 

 into the genito-crural and the external cutaneous, each of which, doubt- 

 less, derives a few filaments from the descending branch of the first. 



The genito-crural descends on the front of the psoas, and breaks 

 into a genital and a crural division. The genital branch passes down 

 upon the external iliac artery, and eventually leaves the abdomen 

 through the inguinal canal, ending in the supply of the cremaster, or 

 over the round ligament. ' Retraction of the testis ' (p. 349) is effected 

 through the influence of this nerve. The crural branch passes beneath 

 Poupart's ligament and through the front of the crural sheath and the 

 fascia lata, and supplies the skin over the outer part of Scarpa's 

 triangle. 



ILIO-HYPOGASTRIC 



ILIO -INGUINAL 



GENITO-CRURAL 



EXT. CUTANEOUS 



ANT. CRURAL 



OBTURATOR 



/ACCESSORY 

 \ OBTURATOR 



The external cutaneous comes through the outer side of the 

 psoas, creeps beneath the iliac fascia, and emerges from the pelvis 

 below the outer end of Poupart's ligament. Then, slowly piercing the 

 fascia lata, it gives cutaneous branches to the buttock and to the outer 

 aspect of the thigh as low as the knee. 



The third and fourth nerves, with the twig from the second, com- 

 bine to give off the anterior crural and the obturator. 



