LUMBAE PLEXUS. 



721 



above the inguinal ligament, it becomes superficial after passing through the 

 subcutaneous inguinal ring and external spermatic fascia (Fig. 623, p. 715). 



Its branches are muscular to the muscles of the abdominal wall, among which it 

 passes, and cutaneous branches (anterior scrotal, or labial nerves), which innervate 



Middle arcuate ligament 



Vena caval opening 



(Esophageal opening in diaphragm 



Aortic opening 



Anterior ramus 



of twelfth 



thoracic nerve 



Quadratus 



lumborum 



lio-hypogastric 



nerve 



Ilio-inguinal 

 nerve 



Lateral 



utaneous nerve 



of thigh 



Femoral nerve ~" 



Genito-femoral 

 nerve 



bturator nerve ~~ 



cending ramus 

 fourth lumbar 



nerve 



interior ramus ..--', 

 of fifth lumbar 



nerve 



. f Medial and 

 j lateral lumbo- 

 . I costal arches 

 Ant. ramus of twelfth 

 thoracic nerve 

 Quadratus 

 lumborum 

 Ilio-hypogastric 

 nerve 

 Ilio-inguinal nerve 



Psoas major 

 Genito-femoral 



Lateral 



cutaneous nerve 

 of thigh 



Iliacus 



Lumbo-sacral 

 trunk 



" Femoral nerve 



Obturator nerve 



FIG. 625. THE MUSCLES AND NERVES ON THE POSTERIOR ABDOMINAL WALL. 



the skin (1) of the anterior abdominal wall over the symphysis pubis, (2) of the 

 thigh over the proximal and medial part of the femoral triangle, and (3) of the 

 superior part of the scrotum, and root and dorsum of the penis (of the mons Veneris 

 and labium rnajus in the female). These last-named branches are contiguous to 

 branches of the perineal and pudendal nerves. No lateral cutaneous branch arises 

 from the ilio- inguinal nerve. It thus corresponds, like the anterior cutaneous 

 part of the ilio-hypogastrie nerve, to the anterior trunk of a typical thoracic nerve. 



47 



