166 



LECTURES GIST THE CENTRAL NERVOUS SYSTEM. 



to arrive at any conclusion concerning the function of the antero- 

 lateral column proper by section experiments on animals. The 

 anterior roots, which contain motor fibres, and also exert a 

 trophic influence on both muscle and nerve, are an important 

 constituent of the columns now under consideration. 



The accompanying- drawing and Fig. 102 will give you an 

 idea of the central course of the anterior roots. 



On reaching the gray substance the component fibres of 

 each bundle separate. There are many and conflicting state- 

 ments as to the ultimate destiny of these fibres. 

 The following explanation, which is based 

 largely on my own investigations, is an at- 

 tempt to harmonize the most important of 

 these statements. 



First, we may consider it as settled that 

 the fibres of the anterior roots pass to the 

 ganglion-cells of the anterior horn, or, rather, 

 become continuous with their axis-cylinder 

 process (see Fig. 92). A few of these fibres 

 pass to the cells of the opposite anterior horn 

 by way of the anterior commissure. 



The nuclei of the anterior roots are con- 



FlG. 101. _ -11 '11 



Passage of the ante- nected by nerve-fibres with the pyramidal 



rinr roots through the . _ . ' ,., 



substance of the spinal tracts. We see lar;e numbers 01 these fibres 



cord. (Diagrammatic.) 



at the bottom of the anterior median fissure 

 passing across the middle line af the anterior direct pyramidal 

 tract. The fibres, from the anterior horn to the lateral crossed 

 pyramidal tract, are less easily demonstrated on account of the 

 obliquity of their course and the extreme difficulty of making a 

 section exactly in their plane. In Fig. 102 these central portions 

 of the motor tract are indicated by fine lines, the peripheral (gan- 

 glion-cells of the roots) with coarse ones. The nature of union 

 between the ganglion-cells and the pyramidal fibres is unknown. 

 Fibres pass from the anterior horn to the lateral and median 

 portions of the ground-bundle of the antero-lateral column. 



