TOUCH, ETC. 15 



Muscular Sense (so called). 



It is difficult to define exactly what is meant by tlie term 

 muscular sense, as it is used by many physiologists. In all 

 probability, the sense which enables us to appreciate the re- 

 sistance, immobility, and elasticity of substances that are 

 grasped, on which we tread, or which, by their weight, are 

 opposed to the exertion of muscular power, 1 is immensely 

 modified by education and habit. Still, it is undoubtedly 

 true that the general sensibility regulates the action of mus- 

 cles to a very great extent. If, for example, the lower ex- 

 tremities be paralyzed as regards sensation, the muscular 

 power remaining intact, the person affected cannot walk, 

 unless he be able to see the ground. In these cases, the in- 

 dividual often falls when blindfolded, for the simple reason 

 that his limbs have lost the sense of contact with the ground, 

 which is nothing more nor less than loss of general sensi- 

 bility. Many curious examples of this kind are to be found 

 in works upon diseases of the nervous system. One of the 

 most striking is a case communicated to Sir Charles Bell by 

 Dr. Ley. The patient was afflicted with partial loss of sensi- 

 bility upon one side of the body, " without, however, any 

 corresponding diminution of power in the muscles of voli- 

 tion, so that she could hold her child in the arm of that side 

 so long as her attention was directed to it ; but, if surround- 

 ing objects withdrew her from the notice of the state of her 

 arm, the flexors gradually relaxed, and the child was in hazard 

 of falling." 2 This is precisely like the phenomena ordinarily 

 described under the head of locomotor ataxia. In this dis- 

 order, there is disease of the posterior columns of the spinal 

 cord, with progressive loss of general sensibility, the mus- 

 cular power, in some instances, being intact. Patients af- 

 fected in this way cannot walk or stand unless they be able 

 to supply the sense of contact by the sight. One of the most 



1 See vol. iii., Movements, p. 460. We have here treated of the sensibility 

 of the muscles in its relations to movements. 



2 BELL, The Nervous System of the Human Body, London, 1844, p. 245. 



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