316 



THE SPINAL NERVES. 



the disc between the third and fourth lumbar vertebrae, and then lying on the fascia 

 covering the anterior surface of that muscle divides at a variable height into an 

 internal or genital, and an external or crural branch. It often bifurcates close to 



Fig. 206. VIEW FROM BEFORE OF THE ANTERIOR BRANCHES OF THE LUMBAR AND SACRAL NERVES 

 WITH THE PLEXUSES. (From Sappey, after Hirschfeld and Leveille.) 



1, lumbar part of the sympathetic cord ; 2, 2', anterior primary division of the twelfth dorsal nerve ; 

 3, first lumbar ; 4, 4', ilio-hypogastric branch of this nerve ; 5, 5', ilio-inguinal branch ; 6, second 

 lumbar nerve ; 7, 7', genito-crural nerve ; 8, 8', external cutaneous nerve of the thigh ; 9, third 

 lumbar nerve ; 10, fourth ; 11, fifth ; 12, lumbo-sacral cord ; 13, iliac branch of the ilio-hypogastric ; 

 14, its abdominal branch ; 15, ilio-inguinal nerve ; 16, external cutaneous nerve of the right side passing 

 out of the abdomen under Poupart's ligament ; 17, 17, 17, cutaneous ramifications of this nerve ; 

 17', the same nerve exposed on the left side ; 18, 18', genital branch of the geuito-crural ; 19, 19, its 

 crural branch on the right side ; 19', the same on the left side exposed as it descends in front of the femoral 

 artery ; 20, 20', anterior crural nerve ; 21, 21', obturator nerve ; 22, left sacral plexus ; 23, aortic 

 plexus of the sympathetic, connected with the other preaortic plexuses and the lumbar ganglia. 



its origin from the plexus, in which case its two branches perforate the psoas 

 muscle in different places. 



(a) The genital 'branch (n. spermaticus externus) lies upon or near the external 

 iliac artery, and sends a filament along that vessel ; then perforating the trans- 

 versalis fascia (or passing through the deep abdominal ring) it traverses the 

 inguinal canal with the spermatic cord, supplies the cremaster muscle, and sends 

 filaments to the skin of the scrotum and adjoining corner of the thigh. In 

 the female it accompanies the round ligament of the uterus to the skin of the 

 groin. 



(b) The crural branch (n. lumboinguinalis) descends upon the psoas muscle 

 beneath Poupart's ligament into the thigh. Immediately below that ligament, and 



