486 Drs. F. W. Mott and C. S. Sherrington. [Mar. 21, 



apsesthete hand is easier, however, to detach from the cage than 

 that of the normal hand. 



We find, again, that a degree of impairment very nearly as great, 

 indeed not obviously different from that produced by section of the 

 sensory roots of the whole series of the nerves of the limb, is produced 

 by section of just those sensory roots which supply the apex of the 

 limb, i.e., the hand and foot. If the whole hand or foot be completely 

 apsesthete by the sections, then the peculiar degree of inability to 

 move the limb, described at the outset of this communication, is 

 obtained in (as far as we can see) its full extent. This result has its 

 converse in the following, which we have also noted : 



(3.) Effect of Section of the whole Series of Sensory Roots belonging 

 to a Limb, with the exception of a Boot that supplies the Hand or Foot. 

 If the sensory roots of the whole series of the spinal nerves 

 belonging to a limb be severed, with the single exception of, in the 

 upper limb, the 8th cervical (distributed to the whole extent of the 

 hand), and in the lower limb the 6th post-thoracic (distributed to the 

 whole extent of the foot), a certain degree of impairment of movement 

 of the limb results, which appears rather as weakness than clumsi- 

 ness, but the degree of impairment is altogether quite slight. The 

 limb is used freely for progression, for climbing, for picking up food, 

 and bringing it to the mouth. The grasp of the partially apa3sthete 

 hand is easier to detach from the cage than that of the hand of the 

 normal side. 



The question naturally arises whether in the interruption of the 

 paths of afferent impulses these can be so dissociated as to decide what 

 share the muscular sense takes in the results observed ? The afferent 

 nerve fibres from muscles per se run, in every case in which they have 

 been examined, in the corresponding spinal roots to the motor. It 

 is possible, therefore, in the hand and foot to sever the sensory roots 

 supplying the muscles, while only partially interfering with those 

 supplying other structures the skin, sheaths of tendons, joints, &c. 

 The converse is also true. On leaving intact the afferent fibres from 

 muscle for the greater part, but interrupting all other afferent channels, 

 we find that the defect of movement produced is nevertheless extreme, 

 as, for instance, when the lowest four cervical and the first thoracic 

 roots are severed. In the same way, when the 5th, 6th, and 7th post- 

 thoracic roots are divided, the sole of the foot is apaesthete, and the 

 defect in movement is extreme, although the afferent fibres from the 

 plantar muscles remain to a large extent intact. 



Conversely, when the 7th, 8th, and 9th post-thoracic roots are 

 severed, the afferent fibres from the plantar muscles are completely 

 interrupted, but the sole of the foot remains sensitive all over, owing 

 to the 6th and 5th roots. In this case (and we have two instances of 

 the kind), the defect of movement, if it exists at all, is not appreciable. 



