682 



STRUCTURE OF THE CEREBELLUM 



[CH. XLTII. 



dendrites intermingle with those of neighbouring cells ; their axons 

 penetrate into the external layer, but their final destination is 

 uncertain. Kamifying among these cells are fibres characterised by 

 possessing bunches of short branches at intervals (moss-fibres of 

 Cajal). 



The peduncles of the cerebellum are three in number superior, 

 middle, and inferior ; we have already had occasion to mention them 

 in our study of the bulb, pons, and mid -brain. The course of the 

 fibres has been chiefly studied by the degeneration method. 



The inferior peduncle, or restiform body, is composed of ascending 

 fibres which pass into it (1) from the cerebellar tracts of the 



FIG. 421. Section of cerebellar cortex, stained by Golgi's method ; I. taken across the lamina; II. in 

 the direction of the lamina; A, outer or molecular layer; B, inner or granular layer ; c, white 

 matter, a, Cell of Purkinje ; &, small cells of inner layer ; c, dendrons of these cells ; d, axis- 

 cylinder process of one of these cells becoming longitudinal in the outer layer ; e, bifurcation of one 

 of these ; g, a similar cell lying in the white matter. (Ramon y Cajal.) 



same side, and (2) from the olivary nucleus of the opposite side; 

 (3) possibly a few fibres from the nucleus gracilis and nucleus 

 cuneatus also join it; and lastly, (4) it receives numerous fibres 

 from the vestibular nerve, or from the nuclei in which it terminates 

 in the pons. The inferior peduncle is thus mainly a spino-cere- 

 bellar path, serving by the cerebellar tracts to unite the same 

 side of the cord with the vermis, and the opposite side of the cord 

 with the cerebellar hemisphere via the opposite olivary nucleus and 

 reticular formation of the bulb. 



The middle peduncle is wholly formed of fibres which originate 

 from the cells of the nuclei pontis : they pass from one side of the 

 pons to the opposite cerebellar hemisphere. This peduncle is the 

 last relay of the cerebro-cerebellar path. 



