iv] I'oKfrriitral or Sciixori/ Area 105 



although much attention has been paid to these disturbances, clinicians arc still in doubt 

 as to the exact portion of the brain on the integrity of which the muscle sense depends for 

 its normal interpretation; indeed it has been localised variously, some maintaining that it 

 is represented along with motion in the central convolutions, others that it finds a place 

 in the parietal lobe, and others that it is situated in more distant regions. It will be 

 interesting to analyse the grounds on which these different views have been built up, 

 and to ascertain which of them fits in most with histological findings and the foregoing 

 remarks. 



( hit of the enticing suggestion that the cells for the reception of sensations originating 

 in muscle must lie in close association with the cells designed for the excitation of movements 

 of the same, the idea has arisen that the muscle sense must be represented in the 

 centres directly governing motion (Bastian, Munk, Mott, etc.). And this view has gained in 

 favour from the remarkable frequency with which an ataxic condition of the muscles, an 

 inability to indicate the position passively communicated to an affected limb, and other signs 

 pointing to loss of this sense, have been found to accompany a motor paralysis. In case 

 after case such associations have been noticed and described: indeed von Monakow, writing 

 only a few years ago, states that but three instances of loss of the muscular sense stand 

 recorded in the literature, in which the central convolutions were found intact. But the 

 validity of this argument entirely depends on whether it can be proved that a lesion limited 

 to the precentral division of the Rolandic area, that is, the part which we now believe truly 

 to govern the motor function, is alone adequate to the production of paralysis of the muscle 

 sense, and this I believe is beyond the power of the upholders of the view. Another 

 impediment prohibiting the acceptance of this thesis is that we are not aware of any path- 

 way by which impressions of muscle sense can be conveyed to the cortex excepting the 

 so-called "cortical lemniscus," and I have already explained that we have strong reasons 

 on the one hand for believing that this tract proceeds to the postcentral cortex, and no 

 evidence on the other side to show that it makes for the precentral or motor area 1 . 



While abolition or dulling of the muscle sense is usually associated with or complicated 

 by motor paralysis, the combination is not an invariable one, for cases of destructive cortical 

 lesion have been recorded in which loss of the "muscle sense" has been the sole disability; 

 and as in all these cases the lesion has been situated in some part of the parietal lobe, 

 they have been fully exploited by those who give their adherence to the belief that the 

 apparatus for the reception and interpretation of the muscle sense is resident in this part 

 (Xothnagel, Redlich, von Monakow, Durante, etc.). The upholders of this view also emphasize 

 the point that in cases of lesion in the parietal lobe the interference with the muscle sense 

 is much more complete than it is in the majority of cases of lesion involving the central 

 convolutions : further, they bring proof to show that in the latter cases, when the destruction 

 spreads in the parietal direction, the sensory disability is increased. 



1 By those who would still uphold the duality of function of the motor area as now denned, it might be argued 

 with some effect that abolition of the muscle sense in a case of lesion in the postcentral division of the Rolandic 

 zone is due to severance of association fibres connecting the central gyri. But the speculation favoured in certain 

 iiuartfrs. that in the motor cortex the laminae of cells are so divided functionally that some are designed for the 

 origin of motor stimuli and others for the reception of sensory impressions, rests on such a frail base that it 

 cannot be countenanced. 



c. 14 



