594 PHYSIOLOGY OF THE NERVE CELL AND THE SPINAL CORD 



p. 



FIG. 266. Diagram showing the upper (A) and lower (C) motor conducting pathways, after 

 Barker. The shaded portion of the cortex represents the motor cortical zone, the cross- 

 hatched portions the motor areas for the various parts of the body. The diagram repre- 

 sents the brain-stem pulled down as indicated by the dotted line running up from the pulvinar 

 of the thalamus. // (in the space between the upper and lower portions of the cerebrum) in- 

 dicates fibers of upper motor pathways, the cell bodies of which are situated in the face area of 

 the cortex; III, fibers of upper pathways derived from pyramidal cells situated in the arm area 

 of the cortex; IV, fibers of upper pathways derived from pyramidal cells in the leg area of the 

 cortex; 1, cell bodies of lower motor pathways; 2 and 2', fibers of pyramidal tract distributed 

 to the cranial nerves ; 3, fibers of pyramidal tract distributed to cord cells which innervate 

 muscles of the upper extremity ; 4, fibers from the pyramidal tract distributed to cord cells 

 which innervate the muscles of the lower extremity. Dec. pyr., decussation of the pyramids. 



