SPINAL CORD AS A PATH OF CONDUCTION. 



165 



movements. On the histological side it has been shown, as stated 

 above, that the fibers, particularly the exogenous fibers, end in 

 nuclei of the medulla and thence are continued forward by the great 

 sensory tract known as the " fillet," to end eventually in that part 

 of the cortex of the cerebrum designated as the area of the body 

 senses. 



Ascending (Afferent or Sensory) Paths in the Lateral 

 Columns. The two best known ascending tracts in these columns 

 are those of Flechsig and of Gowers. The Flechsig bundle or dor- 

 sal cerebellar tract takes its origin in the upper lumbar region, 

 and is composed of axons connected with the tract cells of Clarke's 

 column. The impulses which its fibers convey are brought into 

 the cord through those fibers of the posterior root that end around 

 the cells of Clarke's column. A number of the fibers in this col- 

 umn end doubtless in the gray matter of the upper regions of the 

 cord, but most of them con- 

 tinue upward on the same side, 

 enter the inferior peduncle of 

 the cerebellum, and terminate 

 in the posterior and median 

 portions of the vermiform lobe, 

 mainly on the same side, but 

 partly also on the opposite 

 side. The tract of Gowers, 

 situated ventrally to Flechsig's 

 bundle (gr, Fig. 70), may ex- 

 tend forward into the anterior 

 columns along the periphery 

 of the cord. The two bundles 

 may be more or less intermin- 

 gled at the points of contact. 

 This tract begins also in the 



upper lumbar region, its fibers arising on the same side from tract 

 cells situated in the anterior horn and the so-called intermediate 

 portions of the gray matter. Many of the fibers in this tract doubt- 

 less terminate in the cord itself, since the bundle does not increase 

 regularly in size as it passes up the cord. Most of the bundle 

 continues forward, however, along the ventral side of the pons, 

 gradually shifts more to the dorsal side, and at the level of the 

 superior peduncles of the cerebellum turns backward, for the most 

 part at least, and passes to the cerebellum by way of the superior 

 peduncles and the valve of Vieussens, to end in the vermiform lobe 

 chiefly on the same side, but to some extent on the opposite side * 

 (Fig. 73). Regarding the physiology of these two tracts there is 



* For the literature upon these tracts see Van Gehuchten, " Le Nevraxe," 

 3, 157, 1901. 



a.e 



Fig. 73. To show the course of the fibers 

 of the cerebellar tracts of the cord (Mott) : 

 v.a.c., ventral tract (Gowers); d.a.c., dor- 

 sal tract (Flechsig); s.v., superior vermis; 

 P.C.Q., posterior corpora quadrigemina. 



