380 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



These four tracts are composed almost entirely of 

 nerve fibers that enter the cord by the posterior 

 roots of the spinal nerves. They are therefore sen- 

 sory tracts and forward impulses toward the brain. 

 The termination of the posterier root fibers may be 

 enumerated as follows: 



1. Column of Goll, Burdach, comma tract, Lis- 

 saur's tract. 



2. Arborize about the cells in Clarke's column. 



3. Arborize about the cells in posterior horn. 



4. Arborize about the cells in anterior horn on 

 same and opposite side. 



Lateral Region. The tracts of this region are : (i) 

 Direct Cerebellar 1(2) Go wers 's , or Ascending Antero- 

 lateral; (3) Crossed Pyramidal; (4) Lowenthal's, 

 or Antero-lateral Descending ; (5) Mixed Lateral. 



1. The Direct Cerebellar. This is a band of fibers 

 that lies at the surface of the cord just lateral to the 

 dorso-lateral groove. Its nerve fibers are derived 

 from the cells of the column of Clarke, consequently 

 the tract extends from the last dorsal up to the 

 medulla on the same side. It is an ascending or 

 sensory tract, and, as it is traced upward, becomes 

 wider from the acquisition of axones from the col- 

 umn of Clarke. It enters the cerebellum through 

 the inferior peduncle and finally terminates in the 

 Cerebellar cortex of the superior worm on both sides, 

 chiefly the opposite. 



2. Cowers' s tract lies just in front of the direct 

 Cerebellar and also at the surface of the cord. It is 

 an ascending or sensory tract and some of its fibers 

 are supposed to reach the cerebellum by passing 



