CHAP, i.] 



THE SPINAL CORD. 



687 



of continuity, with the cells of the anterior horn of the same 

 side which give off axis-cylinder processes to form fibres of an 

 anterior root. By means of it, impulses leaving the cells of the 

 cortex of one side of the brain and crossing over in the spinal 

 bulb are able to give rise to efferent impulses in the spinal 

 nerves of the opposite side. Some of the fibres starting from 

 like cells in the cortex do not take exactly this course ; they do 

 not cross over at the decussation of the pyramids, but continue 

 along the same side of the cord, forming in the median part of 

 the anterior column, the direct pyramid tract (Figs. 113, 114). 



r.P 



Ca. 



