222 



19 vertebra 



XXI spinal N 



iliohypogastric N 



guinal N 



genital N 



fig. 2, the XIX spinal (11. thoracic) nerve is the most distal nerve 

 supplying the rectus muscle. The iliac and hypogastric nerves arise 

 from the XX spinal nerve; the inguinal from the XX and XXI spinal 

 nerves by separate branches; the crural and genital nerves from the 



XXI ; the lateral 

 cutaneous nerve 

 arises from the XXI, 

 XXII and XXIII 

 spinal nerves. 



In type B (table 

 3 and fig. 3) the XX 

 spinal nerve in 60"/o 

 of the cases and the 

 XIX spinal nerve in 

 40 Vo, is the last to 

 furnish fibres to the 

 rectus muscle. The 

 iliac and hypo- 

 gastric nerves arise, 

 in the greater pro- 

 portion of the cases, 

 from the XX spinal 

 nerve, but also fre- 

 quently from the 

 XXI. In a number 

 of instances a proxi- 

 mal communicating 

 branch "c" conveys 

 fibres from the XX 

 to the XXI spinal 

 nerve. These fibres 

 thence pass out in 

 certain of the peri- 

 pheral nerves ari- 

 sing directly from the XXI. The inguinal arises in the greater pro- 

 portion of instances from the XXI spinal nerve as do also the genital 

 and crural nerves. The lateral cutaneous nerve arises from the XXI 

 and XXII, and also in about half the instances from the XXIII, spinal 

 nerves. 



In type "C", fig 4, and table 4, a somewhat similar condition 

 of the origin of the border nerves is found. In general, however, there 



obturator N 



XXVIll spinal N- 



Fig. 4. Plexus of type C. 



