244 



THE NERVOUS SYSTEM 



ize the end filaments of fibers which have come down 

 through the cord from the brain. Some fibers have come 

 down in the uncrossed pyramidal tract (column of Turck) 

 on the side opposite the cells, i, 2, 3, 4, and crossed over to 

 the same side through the anterior white commissure ap- 



FIG. 77. Course of nerve fibers in spinal cord. (Kirkes after 

 S chafer.) 



proximately on a level with the cells ; others have decussated 

 in the medulla, and come down in the crossed pyramidal 

 tract on the same side as the cells. In both cases the fibers 

 originated in the brain on the side opposite the cells around 

 which they arborize in the cord. This is the connection 

 which exists between the brain and the anterior root fibers. 

 Not all fibers in the anterior nerve roots are thus pro- 



