ORGANIZATION AND DISTRIBUTION 593 



fibers of which they accompany to the periphery. 3, From this chain the 

 rami efferentes pass into the collateral ganglia, and from these again other 

 branches pass off into the organs, to end in the terminal ganglia. 



The white rami are absent in all the spinal nerves in the regions above 

 the second (occasionally the first) thoracic nerve root, and below the second 



FIG. 419. Scheme of the Constitution and Connections of Gangliated Cord of the Sympathetic. 

 The gangliated cord is indicated on the right, with the arrangement of the fibers arising from 

 ganglion cells. On the left, the roots and trunks of the spinal nerves are shown, with the arrange- 

 ment of the white ramus communicans above and the gray ramus below. The cells of origin in 

 the ventral cord of the fibers constituting the white ramus are not shown. (Cunningham.) 



lumbar nerve root, with the occasional exception of the roots of the third and 

 fourth lumbar nerves. This is a rather restricted field of origin for the pregan- 

 glionic fibers which compose the white rami. These fibers end in adjacent 

 ganglia of the chain, or pass to higher or lower levels or to more peripheral 

 ganglia. 



A peculiarity in the structure of these white medullated visceral nerves is the 

 38 



