SPINAL NERVES 



161 



glossal, turning forwards, 

 and going to the muscles 

 of the tongue (Fig. 51, 7, 

 Fig. 53, i Sp). 



The second pair (Fig. 

 51, //) is very large ; 

 it emerges between the 

 second and third verte- 

 brae, and each is soon 

 joined by the small 

 third nerve (///), which 

 emergesbet ween the third 

 and fourth vertebrae, as 

 well as by a small branch 

 or two from the first, thus 

 forming a simple network 

 or plexus i\ie brachial 

 plexus (br. pi), 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 bet ween the 

 fourth and fifth vertebrae, 

 the fifth (V) between the 

 fifth and sixth, and the 

 sixth (VI) between the 

 sixth and seventh. They 

 all pass obliquely back- 

 wards, and supply the 

 walls of the body, being 

 distributed to both skin 

 and muscles. 



PRACT. ZOOL. 



sci.pl 



FIG 51. The ventral branches of the 

 spinal nerves and the sympathetic of 

 the Frog, ventral view : shown on the 

 right side of the animal only. ( x 2.) 

 / X, spinal nerves ; Ao. systemic arch ; 

 br. pi. brachial plexus ; C. calcareous 

 bodies which surround the spinal 

 ganglia ; D. Ao. dorsal aorta ; fern. 

 femoral nerve ; II. A. iliac artery ; set. 

 sciatic nerve ; set. 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 F y , centra of vertebrae ; Vg. vagus 

 nerve, with its ganglion. (After Gaupp, 

 slightly altered.) 



M 



