196 



VETERINARY PHYSIOLOGY 



in the dorsal region of the cord (see p. 54), and pass 

 out as medullated tibres by the anterior root. From this 

 they pass by the white root to a sympathetic ganghon, 

 whence they may proceed in one of two ways (fig. 46). 



1. They may form synapses with cells in the ganglion, 

 and fibres from these cells may pass — 



(«) Outwards with the splanchnic nerves. 



(6) Back into the spinal nerve by the grey root, and so 

 down the somatic nerve to blood-vessels, muscles of the 



2 



Fig. 98. — Cross section of the Spinal Cord in the cervical region to show 

 the position of the various groups of outgoing fibres : — 1, The crossed 

 pyramidal tract ; 2, the direct pyramidal tract ; 3, the rubro-spinal 

 tract ; 4, the tecto-spinal fibres ; 5. the vestibulo-spinal fibres. 



hairs, sweat glands, etc. The ganglia from which fibres 

 pass back into spinal nerves are known as lateral ganglia. 



(c) Upwards or downwards into other sympathetic 

 ganglia. 



2. They may pass through the ganglion to one more 

 peripherally situated in which they form synapses with 

 other neurons which are continued onwards. The Qranoflia, 

 from which fibres do not pass back, are called collateral 

 ganglia. Before their first interruption these fibres are 



