MUSCLE AND NERVE 



61 



the muscles supplied by the popliteal branch will be thrown into tetanus. 

 This result is not due to the transmission of the nerve impulse in a cen- 

 tripetal direction in the peroneal fibers and in a centrifugal direction in 

 the popliteal fibers, but to the excitation of the latter by the action 

 current developed in the former. 



8. Nerve Currents. Moisten a piece of koalin in normal saline 

 solution and draw it out in two strips about 1 cm. in width and 6 cm. 

 in length. Bend each at right angles and hang them over the edge of 

 a plate of glass at a distance of about 6 mm. from one another. Place 



M. triceps (caput 

 longum) 



M. dexor carpi ulnaris 



Mi flex: digitor. coro- 

 mun, profund. 



M. flex, digitor. sub- 

 lim. (digiti II et III) 



M. flex, digit, subl. 

 (digit: indicis et 

 minimi) 



Nerv. ulnaris 



M. flexor digit, rai 

 M. opponens digi 

 mill. 



M. abductor pollic. brer. 

 M. opponens pollicis 



M. flex. poll. brev. 



M. adductor polite. br*. 



FIG. 38. MOTOR POINTS IN UPPER EXTREMITY. (Howell.) 



the nerve of a nerve-muscle preparation across these strips of clay, 

 allowing the muscle to rest upon the glass. Fill a small beaker with 

 normal saline solution and dip the vertical ends of the clay into it. 

 The muscle contracts every time this contact is made, because it estab- 

 lishes a complete circuit for the interchange of its own demarcation 

 current. 



9. Stimulation of Motor Points. Connect the secondary coil of the 

 inductorium by means of wires of medium caliber with two clinical 

 electrodes (see Fig. 6, D and E), one of which is flat and the other 

 pointed. The flat, indifferent electrode is applied elsewhere to the 



