REACTION OF DEGENERATION. 



577 



stimulated ; similarly, on opening the current, at the anode ( 336). Thus, when the current 

 is closed, the excitability of the nerve is increased at the cathode ( 335), which may act 

 favourably upon the nerve. Increased excitability in electrotonus at the anode, although 

 feebler, has been observed during percutaneous galvanisation in man. This is especially the 

 case by repeatedly reversing the current, sometimes also by opening and closing, or even with 

 a uniform current. If the increase of the excitability is obtained, then the direction of the 

 current increases the excitability on closing the reverse current, and on opening the one in the 

 same direction. 



Bestorative Effect. Further, in using the constant current, we have to consider its restor- 

 ative effects, especially when it is ascending. R. Heidenhain found that feeble and fatigued 

 muscles recover after the passage of a constant current through them. 



M. biceps fem. (cap. long.) 

 (grt. sciat.). 



M. biceps fem. (cap. brev.) 

 (grt. sciat.). 



N. peroneus. 



M. gluteus maximus 

 (great sciatic). 



N. ischiadicus. 



M.adduct.magnus(n.obt.) 



M. semitendinosus (grt. 



sciat.). v 



M. semimembranosus ' 



(grt. sciat.). 



N. tibialis. 



M. gastrocnem.(cap.extr.). 

 M. gastrocnem. (cap. int.). 



M. soleus. 



M. flex. dig. coram, long. 

 M. flexor hallucis longus. 



N. tibialis. 



3 



1 



) a 



Fig. 421. 

 Motor points of the sciatic nerve and its branches ; the peroneal and tibial nerves. 



Lastly, the constant current may be useful from its catalytic or cataphoric action ( 328). 

 The effect is directly upon the tissue elements. It may also act directly or reflexly upon the 

 blood- and lymph-vessels. 



Faradisation in Paralysis. If the primary cause of the paralysis is in the muscles themselves, 

 then the induced current is generally applied directly to the muscles themselves by means of 

 sponge electrodes (fig. 415) ; while, if the motor nerves are the primary seat, then the electrodes 

 are applied over them. The current used must be only of very moderate strength ; strong 

 tetanic contractions are injurious, and so is too prolonged application (JEulcnburg). 



The galvanic current may also be applied to the muscles or to their motor nerves, or to the 

 centres of the latter, or to both muscle and nerve simultaneously. As a rule, the cathode is 

 placed nearer the centre, as it increases the excitability. "When the electrode is moved along 

 the course of the nerve, or when the strength of the current is varied, the action is favoured. 

 If the seat of the lesion is in the central nervous system, then the electrodes are applied along 

 the vertebral column, or on the vertebral column, and the course of the nerves at the same 



2o 



