THE ROOTS OF THE PERIPHERAL NERVES, ETC. 



163 



The region near the gray commissure, which is marked A in 

 Fig. 98, on the left, must contain a distinct system of fibres, 

 because, for example, it never becomes involved in cases of 

 tabes, even though the other parts of the posterior columns 

 degenerate. We may call this the ventral field of the posterior 

 column. 



The posterior columns consist of the entering fibres of the 







FIG. 100. 



Sections through the spinal cord in the upper cervical region, the dorsal region, and 

 the middle of the lumbar region. Boundaries of the different columns of the white 

 substance. 1.. Basal bundle of the anterior column. 2. Basal bundle of posterior column, 

 the wedge-shapi/d column or column of Burdach. 3. Anterior mixed zone of lateral 

 column. 4. Lateral boundary-layer of gray substance. 5. The delicate column, or column 

 of Goll. 6. Lateral cerebellar tract. 7. Crossed pyramidal tract in lateral column. 

 7'. Direct pyramidal tract in anterior column, v, anterior roots. The gray substance is 

 shown black. (After Flechsig.) 



posterior roots. These roots are arranged in such a way that 

 when they first enter the cord they lie on the outer side near the 

 posterior horn, and those entering afterward (i.e., above them) 

 crowd their predecessors inward. Thus it happens that in the 

 cervical region the fibres from the lower extremities are found 

 principally in the column of Goll, while the column of Burdach 

 contains very many fibres from the upper extremities. You 

 must not imagine, gentlemen, that these divisions of the posterior 



