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THE NERVOUS SYSTEM 



fibres which form a white ramus usually terminate at 

 different ganglia, as shown in Fig. 60. Stimulation of a 

 pre-ganglionic fibre always produces an effect over a wider 

 area than does stimulation of a post-ganghonic fibre. The 

 gangha therefore serve as distributing centres. 



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 Fig. 60. — Diagram to show distributing function of sympathetic ganglia. 



Sympathetic System 



The fibres arise in the lateral horns of the cord from the 

 first dorsal to the third or fourth lumbar segment. Emerging 

 from the cord in company with the anterior root, they 

 soon leave this root and enter one of the sympathetic 

 gangha. These are joined together to form the sympa- 

 thetic or lateral chain which runs through the whole length 

 of the trunk and is continued upwards into the neck. 

 Some of the fibres, after passing for a variable distance 

 up and down the chain, end in one of these gangha. Those 

 destined for the abdominal and pelvic viscera pass through 



