552 



NERVOUS SYSTEM 



cord with each other. A certain number of ascending secondary de- 

 generations has been noted in these columns. 



8. Columns of Goll {Posterior Median Cohimns). These delicate 

 columns are situated on either side of the posterior median fissure. 

 They are lost in the lower dorsal region. Their fibres pass upward 

 and pass into the funiculi graciles of the bulb. After section of 

 the cord, ascending secondary degenerations are observed in these 

 columns. 



In addition to these, which are the principal columns of the cord, 

 anatomists have described a tract called Gower's tract, lying between 

 the ascending and descending cerebellar, the lateral bundles and the 

 crossed pyramidal tracts, Clarke's columns, lying next the posterior 



Fig. 133. Diagram of the columns and conducting paths of the spinal cord in the upper dorsal region. 



median fissure and the gray commissure and limited mainly to the 

 dorsal region, and the tract of Lissauer, lying externally to the posterior 

 extremity of the posterior cornu of gray matter. Gower's tract passes 

 to the bulb by the periphery of the anterior pyramids and is thought 

 by some physiologists to contain nerves of pain and nerves of tempera- 

 ture, but the properties of these columns are not very distinctly defined. 

 It is stated that the cells which form the nucleus of the pneumogastric 

 in the bulb are similar to those found in Clarke's columns. It is not 

 known that the fibres of the tract of Lissauer pass to the bulb. It 

 would seem that a description. of eight principal columns renders the 

 anatomy of the cord sufficiently complex without subdividing them into 

 fasciculi that are not as yet known to have any special physiological 

 significance. Still, degenerations attacking these smaller tracts have 



