GREY AND WHITE MATTER IN THE SPINAL CORD 863 



cord. There is reason to believe that the axons of cells of the inter- 

 medio-lateral tract, which pass out as small medullated fibres in 

 the anterior roots, form the preganglionic segments of the efferent 

 vascular and visceral nerves (p. 185)- (4) The cells of the posterior 

 horn, which, although numerous, are smaller than those of the 

 anterior horn. Throughout the whole cord, however, two small 

 groups of cells may be distinguished, one on the lateral side of the 

 horn, about its middle, and the other on the mesial side, a little 

 in front of i.e., ventral to the edges of the substance of Rolando. 

 Both of these groups are broken up by the passage through them 

 of bundles of fibres which form a network, and they are therefore 

 called respectively the group of the lateral and the group of the 

 posterior reticular formation. 



The white matter of the cord is anatomically divided by the 

 position of the nerve-roots and the anterior and posterior fissures 



Fig. 343. Diagrammatic Section of the Spinal Cord in the Cervical and Lumbar 

 Enlargements, to show Tracts of Fibres (Starr), i, antero-median column; 

 2, antero-lateral column; 3, ascending antero-lateral or Gowers' tract; 4, mar- 

 ginal tract (ground bundle, consisting of short endogenous fibres); 5, lateral or 

 crossed pyramidal tract; 6, direct cerebellar tract; 7, tract of Lissauer; 8, ex- 

 ternal portion, and 9, root zone, of Burdach's column; 10, comma tract; u, pos- 

 terior commissural tract; 12, Coil's column; 13, septo-marginal tract. 



into three columns on each side: the anterior, lateral, and posterior 

 columns. The first two, since they are not separated by a perfectly 

 definite boundary, are often grouped together as the antero-lateral 

 column. In the cervical region it may be seen with the microscope 

 that the posterior white column is almost bisected by a septum 

 running in from the pia mater towards the grey commissure. The 

 inner half is called the postero-median column, or column of Goll; 

 the outer half the postero-external column, or column of Burdach 

 (Fig. 343). No localization of any of the other conducting paths 

 in the cord is possible by gross anatomical examination; but by 

 means of the developmental method and the method of degenera- 

 tion the columns of Goll and Burdach can be followed throughout 

 the cord, and several similar areas can be mapped out. We shall 

 only mention those that are physiologically the most important. 



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