200 



ELEMENTS OF MAMMALIAN ANATOMY. 



The direct cerebellar tract occupies the superficial region 

 of the cord later ad of the posterior cornu of gray matter. 

 Its fibers originate from the cells of 

 the more central portion of the gray 

 matter throughout the cord and ter- 

 minate in the cerebellum. Its fibers 

 help to form the inferior peduncle of 

 the cerebellum. 



The antcro-lateral descending 

 cerebellar tract occupies the super- 

 ficial area ventrad of the anterior 

 horn of gray matter. Its fibers 

 originate in the cells of the cerebel- 

 lum and extend caudad in the cord. 

 The ant ero -lateral ascending cere- 

 bellar or Gowers's tract occupies the 

 superficial area laterad of the ante- 

 rior horn. Its fibers probably origi- 

 nate in the cells of central gray 

 matter throughout the cord, and 

 largely terminate in the cerebellum. 

 The lateral ground bundle consists 

 largely of fibers with a short course, 

 many of which are commissural, con- 

 necting the two halves of the spinal 

 cord. 



The crossed, pyramidal tract con- 

 tains the longest fibers of any of the 

 tracts of the central nervous system 

 and occupies a large area just lat- 

 erad of the posterior horn of gray 

 matter. Its fibers originate in the cortical cells of the brain 

 near the crucial sulcus (Fig. 92), and descend as part of the 

 internal capsule, through the corpus striatum and laterad of 



FIG. 103. DIAGRAM OF 

 SOME FIBER TRACTS. 

 DORSAL ASPECT. 



al, Antero-lateral ascend- 

 ing cerebellar tract; c, 

 posterior corpus quad- 

 rigeminum ; cer, lateral 

 lobe of cerebellum, 

 whose median portion 

 is removed ; eg, the two 

 fasciculi gracilis and cu- 

 neatus represented as 

 one; cp, crossed pyra- 

 midal or chief motor 

 tract ; cp' t crossed pyra- 

 midal tract in the re- 

 gion of the cerebral 

 peduncle ; dc, direct 

 cerebellar tract ; fi, the 

 large part of the fillet 

 derived from nc ; nc, 

 nuclei gracilis and cu- 

 neatus; s, decussation 

 of pyramidal tracts ; 

 x, sensory or superior 

 pyramidal decussa- 

 tion ; sp, superior pe- 

 duncle of cerebellum. 



