THE LUMBAR PLEXUS. 



1321 



Variations. — The iliac branch may be absent, its place being taken by the lateral cutaneous 

 branch of the twelfth thoracic nerve. The hypogastric branch may inosculate with the twelfth 

 thoracic and may supply the pyramidalis muscle. 



3. The Ilio-Inguinal Nerve. 



The ilio-inguinal nerve (n. ilioinguinalis) (Fig. 1107) is the second branch ot 

 the kmibar plexus and is somewhat smaller than the ilio-hypogastric. Its fibres 

 usually arise from the first lumbar nerve, with accessions from the twelfth thoracic. 



Fig. I 107. 



XII. rib 

 XII. thoracic nerve 



Quadratus lumborum 

 Psoas magnus 



External oblique 



Lateral cutaneous branch 

 of XII. dorsal nerve 

 Internal oblique 

 Transversalis 



Ilio-hypogastric nerve 



Ilio-inguinal nerve 



Iliac branch of 

 ilio-hypogaslric 



Lateral cutaneous branch 

 of XII. dorsal nerve 



External cutaneous nerve 



Anterior crural nerve 

 Genital branch of 

 genito-crural nerve 



Crural branch of 



genito-crural nerve 



Branches of middle 



cutaneous nerve 



I. lumbar ganglion 



Rami communicantes 



Aorta 



IV. lumbar nerve 



V. lumbar ganglion 

 V. lumbar nerve 

 Part of V. lumbar ganglion 



Genito-crural nerve 



, — I. sacral ganglion 

 I. sacral nerve 



II. sacral nerve 



IV. sacral ganglion 

 Obturator nerve 

 Accessory obturator nerve 



( Hypogastric branches 

 I of ilio-hypogastric nerve 



Ilio-inguinal nerve 



Branch of internal 

 cutaneous nerve 



Deep dissection, showing nerves arising from lumbar plexus and lower part 

 of sympathetic gangliated cord. 



Sometimes it arises entirely from the twelfth thoracic or from the second lumbar or 

 from the loop between the first and second lumbar nerves. It occasionally forms a 

 common trunk of considerable length with the ilio-hypogastric. In the early part 



