DISSECTION OF THE DOG 



11 .5 



region. The constitution <>t' the nerves arising from tin- Lumbar and sacral 

 plexus maj be summarised in this place. 



.Y. ilio-hypogastricus is formed hy the lirsl lumbar. 



A'. Mo inguinalis consists mainly of fibres derived from ili<' Becond lumbar 

 nerve, but has, in addition, a reinforcement from tin- first Lumbar. 



N.genito-femoralis generally contains fibres from the third and fourth 

 lumbar nerves, but occasionally those from the fourth are absent. 



A'. ciifftiK us r maris lateralis is mainly formed by the fourth lumbar nerve, 

 but it also receives a branch from the third. 



N.femoraiis is constituted by the union of two main roots from the fifth 

 and sixth lumbar nerves, with an occasional thin root from the fourth nerve 

 in addition. 



n. eutaneus 

 femoris posterior 



n. pudendus 



n. hccmnrrhiidalis 

 caudalis 



n. ischiadicus 



n. geirito- 

 femoralis 



n. glulccus 

 cranial is 



n. femoralis 

 Vu.. 4:!. —Plexus of lumbar and sacral nerves 



n. eutaneus 

 femoris 

 lateralis 



n. ilio-inguinalis 



N. obt 11 raio rii/s results from the conjunction of three roots : namely, from 

 the fourth, fifth, and sixth lumbar nerves. 



N. isch indie a* is formed by the fusion of large roots from the sixth and 

 seventh lumbar nerves, and a smaller root from the first sacral nerve. 



N. glutcBus cranialis receives its fibres from the same spinal nerves as 

 does the sciatic nerve. 



N. glutceus caudalis contains fibres contributed by the first and second 

 sacral nerves. 



N. pudendus has roots from the first, second, and third sacral nerves. 



N. eutaneus femoris posterior is formed by the second and third sacral nerves. 



N. hcemorrhoidalis caudalis is composed of fibres derived from the first 

 and second sacral nerves. 



With the exception of the obturator and caudal hemorrhoidal nerves, 

 all the above have been examined. 



N. obturatorius. — The obturator nerve is of considerable size, and is 

 formed by roots which join medial to the ilio-psoas muscle. The nerve crosses 

 the medial surface of the ilium and enters the obturator foramen by insinuating 



