114 THE SPINAL CORD AND CEREBELLUM 



cerebrum to the pyramid makes connections with 

 several cranial nerves, whilst its fibres also give off 

 collaterals to form similar connections in the spinal 

 nerves.* These connections may be held to constitute 

 part of the co-ordinating system of the body, whereby 

 the muscles are brought into functional relations with 

 the sense organs and with one another. 

 The idio- The function of the remaining tracts of fibres which 



lateral . . . ° . 



pyramidal are intimately connected with or which form part of 

 the pyramidal system is more difficult to determine. 

 One of these, the idiolateral, occupying, it will be 

 remembered, the same position in the cord as the 

 contra-lateral fibres of the crossed pyramidal tract, 

 and being mingled with them, undergoes degeneration, 

 according to Foster, when a lesion occurs in the 

 hemisphere of the same side. The other, described by 

 Bechterew as occupying a position in the crossed 

 pyramidal tract almost identical with that of those 

 just mentioned, degenerates when the inferior peduncle 

 of the cerebellum is severed. It consists, indeed, of 

 Of the the group of fibres termed the intermediate bundle or 

 mediate tract, which, proceeding from the cerebellum, join 

 the pyramidal fibres in the medulla oblongata. 

 Severance of the inferior peduncle, however, not only 

 leads to degeneration in their fibres, but also in the 

 crossed pyramidal fibres of the same side, and even 

 in those of the anterior roots of the spinal nerves.f 



* Foster, loc. cit., p. 961. 



t Bechterew, loo. cit., pp. 96, 97 : 'In der Pyramidenbahn 

 sind, wis ich unlangst naohgewissen, zerstreute Fasern ein- 

 gelagert, welohe einer etwas friiheren Entwickelungsphase 



