84O METHOD OF TESTING THE MUSCULAR SENSE. 



muscular sense was retained completely. A frog deprived of its skin can spring 

 without any apparent disturbance. The muscular sense is also greatly aided by 

 the sensibility of the joints, bones, and fasciae. Many muscles, e.g., those of respira- 

 tion, have only slight muscular sensibility, while it seems to be absent normally in 

 the heart and non-striped muscle. 



[The muscular sense stands midway between special and common sensations, and 

 by it we obtain a knowledge of the condition of our muscles, and to what extent 

 they are contracted ; also the position of the various parts of our bodies and the 

 resistance offered by external objects. Thus, sensations accompanying muscular 

 movement are two-fold (a) the movements in the unopposed muscles, as the 

 movements of the limbs in space ; and (b) those of resistance where there is 

 opposition to the movement, as in lifting a weight. In the latter case the sensa- 

 tions due to innervation are important, and of course in such cases we have also to 

 take into account the sensations obtained from mere pressure upon the skin. Oufc 

 sensations derived from muscular movements depend on the direction and duration 

 of the movements. On the sensations thus conveyed to the sensorium, we form 

 judgments as to the direction of a point in space, as well as of the distance between 

 two points in space. This is very marked in the case of the ocular muscles. It is 

 also evident that the muscular sense is intimately related to, and often combined 

 with, the exercise of the sensation of touch and sight (Sidly).] 



Methods of Testing. Weights are wrapped in a towel and suspended to the part to be 

 tested. The patient estimates the weight by raising and lowering it. The electro-muscular 

 sensibility also 111:13' be proved thus: cause the muscles to contract by means of induction shocks, 

 and observe the sensation thereby produced. [Direct the patient to place his feet together 

 while standing, and then close his eyes. A healthy person can stand quite steady, but in one 

 with the muscular sense impaired, as in locomotor ataxia, the patient may move to and fro, or 

 even fall (p. 647). Again, a person with his muscular sense impaired may not be able to touch 

 accurately and at once some part of his body, when his eyes are closed. ] 



A healthy person perceives a weight of 1 gramme applied to his upper arm ; when a weight of 

 15 grms. is applied, he perceives an addition of 1 grm. If the original weight be 50 grms., he 

 will detect the addition of 2 grms. ; if the original weight be 100 grms., he will detect 3 grms. 

 The weight detectable by the individual finger varies. With the leg, when the weight is 

 applied at the knee, the individual may detect 30 to 40 grms.; but sometimes only a greater 

 weight. Often one can detect a difference of 10 to 20, or 30 to 70 grms. 



Section of a sensory nerve causes disturbance of the fine graduation of move- 

 ment (p. 619). Meynert supposes that the cerebral centre for muscular sensibility 

 lies in the motor cortical centres, the muscles being connected by motor and 

 sensory paths with the ganglionic cells in these centres. 



Too severe muscular exercise causes the sensation of fatigue, o]ipressio?i, and 

 weight in the limbs ( 304). 



Pathological. Abnormal increase of the muscular sense is rare {muscular hyperalgia and 

 hypcrccstkesia), as in anxictas tibiarum, a painful condition of unrest which leads to a continual 

 change in the ]>osition of the limbs. In cramp there is intense pain, due to stimulation of the 

 sensory nerves of the muscle, and the same is the case in inflammation. Diminution of the 

 muscular sensibility occurs in some choreic and ataxic persons ( 364, 5). In locomotor ataxia 

 the muscular sense of the upper extremities may be normal or weakened, while it is usually con- 

 siderably diminished in the legs. [The muscular sense is said to be increased in the hvpnotic 

 condition, and in somnambulists.] 



