SPINAL NERVES 



161 



between the second and 

 third vertebrae, and each 

 is soon joined by the small 

 third nerve (///) which 

 emerges between the third 

 and fourth vertebrae, as well 

 as by a small branch or two 

 from the first, thus forming 

 a simple network or plexus 

 the brachial plexus (br. 

 pl\ from which pass off 

 nerves to the fore-limb, 

 supplying both skin and 

 muscles. 



The fourth, fifth, and 

 sixth nerves take a very 

 similar course.. The fourth 

 (IV) emerges between the 

 fourth and fifth vertebra, 

 the fifth ( V) between the 

 fifth and sixth, and the 

 sixth ( VI) between the sixth 

 and seventh. They all pass 

 obliquely backwards, and 

 supply the walls of the 

 body, being distributed to 

 both skin and muscles. 



The seventh, eighth and 

 ninth nerves supply the 

 muscles and skin of the 

 hind-limbs. The seventh 

 ( VII) leaves the neural 

 canal between the seventh 



PRACT. ZOOL. 



firfol 



sci.pl 



fe 



FIG. 51. The ventral branches of the 

 spinal nerves and the sympathetic of 

 the frog, ventral view : shown on the 



: irog, vent 

 ght side only. 



spinal nerve: 

 br. pi. brachial plexus ; C. calcareous 



rign 

 IX, 



spinal nerves ; ^40. systemic arch ; 



bodies which surround the spinal 

 ganglia ; D. Ao. dorsal aorta ; fern, 

 femoral nerve ; //. A. iliac artery ; sci. 

 sciatic nerve ; sci. pi. sciatic plexus ; 

 Sk. skull ; Sp. A . splanchnic artery ; 

 Sy. sympathetic cord ; Sy. c. communi- 

 cating branches between the sympa- 

 thetic and spinal nerves ; Sy. g. 

 sympathetic ganglia ; Ust. urostyle ; 

 V* K 9 . centra of vertebrae ; Vg. vagus 

 nerve, with its ganglion. (After 

 Gaupp. slightly modified.) 



M 



