172 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



in the dorsal cerebellospinal tract (Flechsig). Where this tract 

 separates from the cerebellospinal fasciculus it is stated * that it 

 gives off a number of fibers which enter the restiform body with 

 the cerebellospinal fasciculus to end in the cerebellum. This 

 and other facts indicate that the two tracts constitute a com- 

 mon system. Regarding the physiology of these two tracts 

 there is little experimental and not much clinical evidence. 

 Some observers have cut the cerebellospinal fasciculus in ani- 

 mals, but with no very obvious effect except again a slight 

 degree of ataxia in the movements below the lesion and some 

 loss of muscular tone.f This result, together with the fact 

 that the bundle ends in the cerebellum, gives reason for be- 

 lieving that the fibers convey afferent impulses from the muscles. 

 As we shall see, much evidence of various kinds connects the cere- 

 bellum with the co-ordination of the muscles of the body in the 

 complex movements of standing and locomotion. This power 

 of co-ordination in turn depends upon the afferent impulses 

 from the muscles and the joints and other so-called deep sen- 

 sory parts, and since the fibers of the cerebellospinal fasciculus 

 end in the cerebellum, and since experimental lesion of them 

 gives no loss of cutaneous sensibility, but some degree of ataxia, 

 it seems justifiable to conclude that these fibers are physiolog- 

 ically muscle-sense fibers. The similar fibers in the posterior 

 funiculi end eventually in the cortex of the cerebrum, and may 

 be supposed, therefore, to mediate our conscious muscular sensa- 

 tions, but these fibers in the cerebellospinal tract end in the cere- 

 bellum, an organ which, so far as we know, gives rise to no con- 

 scious sensations. To speak of them, therefore, as muscle-sense 

 fibers may be somewhat misleading, and it may be better to follow 

 the plan of designating them as the non-sensory afferent fibers 

 arising from tissues beneath the skin, such as the muscles, the 

 tendons, and the ligaments round the joints. The superfi- 

 cial anterolateral fasciculus has been the subject of some ex- 

 perimental study from the physiological side, but the results 

 have been negative. Clinically, the tract may be involved 

 in pathological or traumatic lesions of the lateral funiculi. Cow- 

 ers J gives a history of some such cases, which lead him to be- 

 lieve that this tract constitutes a pathway for pain impulses, 

 and this view or the view that it conducts the impulses of both pain 

 and temperature has been more or less generally accepted. Entire 



* Schafer and Bruce, "Journal of Physiology," 1907 ("Proc. Physiol. 

 Soc"). 



t Bing. "Archiv fur Physiologic," 1906, 250; also Horsley and Macnalty, 

 hoc. cit. 



X Gowers, "Lancet," 1886. 



