PHYSIOLOGICAL ANATOMY OF THE SPINAL CORD. 593 



B 



A 



AR 



AR 



cord, the fibres of the direct cerebellar fasciculi show ascending secondary 

 degeneration. Their trophic centres probably are the cells of the posterior 

 cornua of gray matter of the cord. 



7. Columns of Burdacli. These columns (D, in Fig. 217) are in the pos- 

 terior columns of the cord, between the columns of Goll and the posterior 

 cornua of gray matter. Their fibres connect some of the cells of the gray 

 matter of the posterior cornua with the 



cerebellum ; or at least the fibres pass up- 

 ward and are connected with the restiform 

 bodies, going to the cerebellum through 

 the inferior peduncles. The fibres also 

 connect nerve-cells of different portions of 

 the cord with each other. No secondary 

 degenerations have been noted in these 

 columns. 



8. Columns of Goll These delicate 

 columns (C, in Fig. 217) are situated on 

 either side of the posterior median fissure. 

 They are lost in the lower dorsal or upper 

 lumbar region. Their fibres pass upward 

 and are lost in the funiculi graciles of the 

 medulla oblongata. After section of the 

 cord, ascending secondary degeneration is 

 observed in the fibres of these columns. 



Directions of Nerve - Fibres in the 

 Cord. Many of the points in the descrip- 

 tion of the course and connections of the 

 fibres in the cord are given as probable. 

 Anatomical observations have been some- 

 what contradictory, but these have been 

 corrected or verified by following the paths 

 of degeneration. What is called secondary degeneration is the anatomical 

 change in the nerve-fibres which follows separation of the fibres from the 

 cells which act as their trophic centres, or the centres presiding over their 

 nutrition, these changes being secondary to the destruction or degeneration 

 of the centres. 



The fibres of the anterior roots of the spinal nerves, following these fibres 

 inward and upward, pass directly to the large, multipolar motor cells of the 

 anterior cornua of gray matter and have no direct connection with' the white 

 columns. Their direction through the white columns of the cord is oblique 

 and slightly upward. They are continuous with the axis-cylinder prolonga- 

 tions of the cells. From the nerve-cells, prolongations are given off, by 

 branching processes, in two bundles, median and lateral. The fibres of the 

 median bundle pass to the anterior white commissure, in which they decus- 

 sate. They then go each one to the column of Tiirck on the opposite side 

 and pass upward in the so-called direct pyramidal tracts. The fibres of the 



FIG. 217. Diagram of the columns and con- 

 ducting paths in the spinal cord in the 

 tipper dorsal region (enlarged and modi- 

 fied from Landois). 



AR, AR, anterior roots of the spinal nerves ; 

 PR, PR, posterior roots ; A, columns of 

 Tiirck ; B, anterior fundamental fascicu- 

 li ; O, columns of Goll ; D, columns of 

 Burdach ; E. E, anterior radicular zones ; 

 F, F, mixed lateral columns ; G, G, 

 crossed pyramidal tracts ; H, H, direct 

 cerebellar fasciculi. The gray matter of 

 the cord is in black. The figure also 

 shows the anterior and posterior median 

 fissures, the white and gray commissures 

 and the central canal. 



