140 THE SURGICAL PHYSIOLOGY 



or hemiplegia. The pain may be due to such a 

 cause as the crises of locomotor ataxia, or the agonies 

 of inoperable cancer. 



When many roots are cut for spasticity, it is 

 necessary to leave one or two intact, or a very decided 

 amount of ataxy may be induced. 



THE DIAGNOSIS AND LOCALIZATION OF 

 TUMOURS OF THE SPINAL CORD. 



Tumours of the spinal cord do not occur so 

 commonly as tumours of the brain, but the results of 

 surgical removal are a good deal better. It becomes 

 important, therefore, to know how to make the 

 diagnosis. 



Before entering upon this subject, we must remind 

 ourselves of the functions of the great paths or tracts 

 running up or down the spinal cord. 



DESCENDING TRACTS. The pyramidal tracts convey 

 motor impulses from the cortex, and particularly 

 those acquired movements which call for skill and 

 finesse. They also inhibit muscular tone. The 

 rubrospinal tract (Monakow's bundle) controls stock 

 movements such as standing, sitting, and walking. 

 This tract starts in the red nucleus in the isthmus, 

 and it is largely by its means that a man w y hose 

 pyramidals have been destroyed in the brain may 

 still be able to get about. It would appear, also, 

 that this tract carries down impulses that inhibit 

 any excess of muscular tone. The vestibulospinal 

 and other tracts pass down in the antero-lateral 

 columns, from the region of the pons and medulla. 

 They* are important paths for motor impulses, at 



