THE MOTOR TRACTS. 



Grus 



cerebri. 

 Fourth 

 nerve (note 

 the double 

 decussation. 



Medulla. 



Third nerve. 



Fifth nerve. 



Anterior 

 nerve-root. 



Anterior 

 commissure. 



Spinal cord. 



FIG. 13. Diagram of the pyramidal fibres and the nuclei of the cranial and spinal 

 motor nerves. (From Morris's Anatomy, after Arthur Robinson.) 



[To face page 182. 



