CHAP. XXVI, ] VOLUNTARY MOVEMENTS. 567 



may transmit limitations capable of calling into action the closely 

 united double groups of Spinal Nerve-cells which minister to the 

 bilateral movements of the trunk. The case in regard to the 

 bilateral movements concerned in Speech will be specially referred 

 to in a subsequent chapter. 



The precise mode in which the Corpus Striatum acts 

 can only be dimly conjectured. No one has expressed 

 the kind of view which has been held by many, better or 

 more fully than Broadbent, when he says*: 



"The Corpus Striatum is the motor ganglion lor the entire 

 opposite half of the body. It translates volitions into actions, or 

 puts in execution the commands of the Intellect ; that is, it 

 selects, so to speak, the motor nerve nuclei in the medulla and cord 

 appropriate for the performance of the desired action, and sends 

 down the impulses which sets them in motion. These impulses 

 are transmitted through fibres, and the fibres must start from 

 cell processes in the corpus striatum. A given movement, therefore, 

 must be represented in the Corpus Striatum by a group or groups 

 of cells giving off downward processes, which become fibres of the 

 motor tract of the cord. When the movement is simple, or when 

 the co-ordination required can be effected by the cord as in walking, 

 the cell group will be small, and the descending fibres few. When 

 the movement is complex and delicate, and guided by vision or by 

 the conscious attention, as in writing or drawing, the cell-groups will 

 be large and definite, and the descending fibres numerous. There 

 will not be a separate group of cells for each movement; but the 

 same cells may be differently combined, just as different combina- 

 tions of carbon, hydrogen, oxygen, and nitrogen form the basis of 

 all organic substances. Words which require for their utterance 

 the simultaneous co-operation of muscles of the chest, larynx, 

 tongue, lips, etc., and the exquisite and rapid adjustment of their 

 movements concerned in phonation and articulation, must be repre- 

 sented in the Corpus Striatum by very large groups of cells, and 

 not in that of one side only but in both." 



This view as to the functions of the Corpora Striata in 

 regard to Voluntary Movements may be supplemented 



* " Brit. Med. Journal," April 1, 1876. 



