STRUCTURE OF THE NERVOUS SYSTEM 



28l 



These are called nerve trunks, and the smaller branches 

 into which they divide are called nerves. The nerves also 

 undergo division until they 

 terminate as fine thread-like 

 structures in all parts of the 

 body. The distribution of 

 nerve terminations, however, 

 is not uniform, as might be 

 supposed, but the skin and im- 

 portant organs like the heart, 

 stomach, and muscles are the 

 more abundantly supplied. 

 On many of the nerves are 

 small rounded masses, called 

 ganglia, and from many of 

 these small nerves also emerge. 

 At certain places the nerves 

 and ganglia are so numerous 

 as to form a kind of network, 

 known as a plexus. 



It is through these struc- 

 tures brain and spinal cord, 

 nerve trunks and nerves, gan- 

 glia and nerve terminations 

 that connections are estab- 

 lished between all parts of the 

 body, but more especially be- 

 tween the surface of the body 

 and the organs within. FIG. 125. Diagram of nerve 



The Neurons, or Nerve Cells, skeleton. The illustration shows 



-While a hasty examination the extent and general arrangement 

 J of the nervous tissue. A. Brain. 



of the nerve skeleton is suffi- B Spinal cord ^ Nerve trunks 



Cient to show the connection and nerves. G. Ganglia. 



