614 



THE FUNCTION OF THE SPINAL CORD 



from cells of the corresponding gray matter. The latter are short fibers, i.e., 

 associative in their function, while the former belong to the projection system. 



Classification of the Tracts of the Spinal Cord. In accordance 

 with the foregoing histological discussion, it will be seen that the 



FIG. 304. DIAGRAM SHOWING THE COUESE, OHIGIN AND TERMINATION OF THE FIBERS OF 



THE PRINCIPAL TRACTS OF THE WHITE MATTER OF THE SPINAL CORD. 

 Descending tracts: la, a fiber of the crossed pyramid or corticospinal tract; lb, an 

 uncrossed fiber of the pyramid or corticospinal tract passing to the lateral column of 

 the same side; 2, a fiber of the ventral pyramid or cortico-spinal tract; 3, a fiber of the 

 ventrolateral descending or pontospinal tract; 4, a fiber of the rubrospinal tract; 5, 

 a fiber of the common tract. Ascending tracts: 6, a fiber of the dorsomesial spino- 

 bulbar tract; 7, fibers of the dorsolateral spinobulbar tract; 9, one belonging to the 

 dorsal spinocerebellar ; 10, a fiber of the ventral spinocerebellar tract. (Quain, Ele- 

 ments of Anatomy.) 



different fasciculi of the spinal cord constitute different descending 

 and ascending tracts. In this connection brief reference should also 

 be made to a number of small and narrow tracts which have been 



