SENSITIVITY OF MUSCLES JOINTS, AND BONES, ion 



one and the same sensation of tension of muscle (including tendon), would, 

 if memorable, make a kinesthetic complex for judging and standardising 

 comparable complexes. 1 Sense organs of joints certainly contribute importantly 

 to the various kinds of muscular sense perceptions. 



The skin does not much assist muscular sense. Cutaneous anaes- 

 thesia inflicts little injury on the sense of movement or posture. That 

 it has some influence, however, is undeniable. Of two equal weights, 

 one hollow and therefore the larger, lifted successively, the larger 

 seems the lighter, 2 even if the test be made when the eyes are shut. 

 Tested with the eyes open, 3 the larger weight seems more distinctly the 

 lighter than when touch is appealed to apart from vision. A pound of 

 lead is, as regards sensation, heavier than is a pound of feathers. 



Sensitivity of muscles, joints, and bones, as evidenced by 

 reflexes. — The muscular structures, including tendon, appear insensitive 

 under many mechanical, thermal, electrical, and chemical stimuli, 

 known to be efficient in other cases. 



Haller and his pupils concluded that neither tendon nor muscle is sentient. 

 Bichat considered the former slightly sensitive. Schiff, 4 Bernstein, 5 and 

 Bloch 6 have all, more recently, maintained the insensibility of muscle. 

 Rollett, 7 after finding nerve-endings in tendon, tried to elicit reflexes from 

 tendons, but failed to obtain any. Reflexes can, however, be initiated from 

 these structures. One very constantly obtainable is initiated by compressing 

 the tibialis anticus tendon (cat) just above the annular ligament ; the response 

 is given by the adductor muscle of the thigh. 



The tendon reflexes are misleadingly so called. Thus, in their prototype 

 the "knee-jerk," the tendon is not necessary to the reaction, and the reaction 

 has so short a latency that it cannot be reflex. There are, however, nearly 

 thirty named " tendon reflexes" studied in the human body, and some of these 

 may be true reflexes. It is not possible to decide the point until the latent 

 period has been measured in each instance. 



From the muscles themselves, in spite of former negative results, 

 there is now evidence of the obtaining of reflexes. Vasomotor reflexes 

 can be evoked by kneading exposed muscles in the curarised rabbit. 8 

 The effect is usually a fall of general blood pressure. Electrical 

 stimulation of the muscles and nerves less constantly produces a fall, 

 often a rise. The knee-jerk can be inhibited by stretching or compress- 

 ing any of the hamstring muscles, 9 even when the muscle is completely 

 freed from all connection with the body except through its nerve trunk 

 and its blood vessels. I noted movements of the opposite eye and 

 pricking of the ears (cat), produced by gently stretching the inferior 

 oblique muscle, freed from all connections but its nerve and blood 

 vessels, and suspended between two pairs of ivory-tipped forceps. 10 A 

 twitch can be evoked from the tibialis anticus, isolated but for nerve and 

 blood vessels, by jarring it, especially lengthwise. The sudden relaxation 

 of a passively stretched muscle I have often seen evoke a reflex, e.g. the 



1 See also in regard to this, Delabarre, " Inaug. Diss.," Freiburg, 1891. 



2 Charpentier, Arch, dc physiol. norm, et path., Paris, 1891, Ser. 5, tome iii. p. 122. 



8 Gilbert, Stud. Yale Psychol. Lab., New Haven, 1894, vol. ii. p. 43; Seashore, 

 ibid., 1895, vol. iii. p. 1. 



4 "Muskel- u. Nervenphysiol.," Lahr, 1858, S. 157. 



5 " Untersuch. ueber d. Nerven- u. Muskelsystem," 1871, S. 239. 

 8 Rev. scien/., Paris, 1890, tome xlv. p. 294. 



7 Eulenburg's " Real - Encyc. , " 1888 : Bd. xiii. S. 581. 



8 Kleen, Skandin. Arch.f. Physiol., Leipzig, 1890, Bd. i. S. 247. 



9 Sherrington, Proc. Roy. Soc. London, 1893, vol. Iii. 10 Ibid. 



