OF THE SPINAL CORD 203 



the sense (stereognosis) by which we recognize unseen 

 objects by the feel — as on putting a hand into a 

 pocket containing coins, keys, a penknife, paper, 

 etc. — also travels by this route. 



Thus we find that whilst muscular sense, stereo- 

 gnosis and tactile discrimination pass up the cord 

 uncrossed, heat, cold, and pain sense cross, usually 

 about six segments above their point of entry, and 

 there is a cell-station in the grey matter. Hence 

 syringomyelia and other lesions of the grey matter 

 abolish temperature and pain sense. Sherrington 

 has shown that the pain impulses are not totally 

 crossed ; a few pass up on the same side. Tactile 

 sense, apparently, can follow either of these two 

 routes. 



A tumour of the spinal cord : — 



1. May affect the nerve-roots, in which case the 

 symptoms may be confined to those roots. 



2. May press on one side of the spinal cord. In 

 this case there is usually pain radiating along the 

 nerve-roots involved at the same time, which is 

 important in the diagnosis. 



Let us take the case of a tumour in the left lower 

 cervical area. This will involve : — 



(i). The emerging roots of the lower cervical nerves 

 on the left side, causing pain, dulhng of sensation, 

 and flaccid paralysis with loss of reflexes, wasting, 

 and reaction of degeneration, in the left arm. 



(ii). The pyramidal, rubrospinal, and vestibulo- 

 spinal tracts on the left side, causing paralysis of 

 the left leg. Inasmuch as the pyramidal and rubro- 

 spinal tracts are involved, muscular tone will be 



