FUNCTIONS OF THE BRAIN. 37 



(3) Descending degenerations show the intimate connec- 

 tion of the rolaudic regions of the cortex with the motor 

 tracts of the cord. AYhen, either in man or in the lower ani- 

 mals, these regions are destroyed, a peculiar degenerative 

 change known as secondary sclerosis is found to extend 

 downwards through the white fibrous substance of the 

 brain in a perfectly definite manner, affecting certain dis- 

 tinct strands which pass through the inner capsule, crura^. 

 and pons, into the anterior pyramids of the medulla oblon- 

 gata, and from thence (partly crossing to the other side) 

 downwards into the anterior (direct) and lateral (crossed). 

 columns of the spinal cord. 



(4) Anatomical proof of the continuity of the rolandic- 

 regions with these motor columns of the cord is also clearly 

 given. riechsig's ' Pyramidenbahn ' forms an uninter- 

 rupted strand (distinctly traceable in human embryos,, 

 before its fibres have acquired their white 'medullary 

 sheath ') passing upwards from the pyramids of the me- 

 dulla, and traversing the internal capsule and corona radi- 

 ata to the convolutions in question (Fig. 10). None of the 

 inferior gray matter of the brain seems to have any connec- 

 tion with this important fibrous strand. It passes directly 

 from the cortex to the motor arrangements in the cord, de- 

 pending for its proper nutrition (as the facts of degenera- 

 tion show) on the influence of the cortical cells, just as motor 

 nerves depend for their nutrition on that of the cells of the 

 spinal cord. Electrical stimulation of this motor strand in 

 any accessible j)ai't of its course has been shown in dogs to 

 produce movements analogous to those which excitement 

 of the cortical surface calls forth. 



One of the most instructive proofs of motor localization, 

 in the cortex is that furnished by the disease now called 

 aphemia, or motor Aphasia. Motor aphasia is neither loss 

 of voice nor paralysis of the tongue or lijDs. The patient's 

 voice is as strong as ever, and all the innervations of hi» 

 hypoglossal and facial nerves, except those necessary for 

 speaking, may go on perfectly well. He can laugh and cry, 

 and even sing ; but he either is unable to utter any words at 

 all ; or a few meaningless stock phrases form his only speech ; 

 or else he speaks incoherently and confusedly, mispronounc- 



