98 



PSYCHOBIOLOGY 



largely composed of non-medullated fibers; hence the difference in color. 

 The pre-ganglionic fibers do not necessarily terminate in the ganglia near- 

 est to the white rami over which they run. Some fibers pass up or down 

 the chain to other lateral ganglia, and others run through to the collateral 

 ganglia. 16 The post- ganglionic fibers given back to a spinal nerve through 



Fig. 78. Diagram of the motor connections of the sympathetic chain. (Quain's 

 Anatomy, after Van Gehuchten.) 



its gray ramus are connected with the pre-ganglionic fibers of a number 

 of white rami. 



The distribution of the post-ganglionic sympathetic fibers and the 

 spinal origin of the pre-ganglionic fibers with which they are connected 

 may be indicated briefly. 



The first five thoracic nerve-roots, chiefly the second and third, supply 

 the head and neck by way of the ' superior cervical ' ganglion, and the 



16 Some fibers run through both lateral and collateral ganglia, terminating in 

 peripheral ganglia (or terminal ganglia) in close relation to the organs supplied. 



