Nervous and mental diseases . uted to contract more orless vigorously in proportion to the intensity of the current is to be particularly noted that upon allowing the current to passthe response is instantaneous, and that the muscular contraction atonce reaches its maximum and maintains it until the current is modi- ELECTRICAL CONDITIONS. 43 fied. This phenomenon attends stimulation by either the positive ornegative faradic pole or electrode, but the negative causes a slightlystronger effect. If, now, the constant current be substituted, we notice, first of all, thatmild currents a
Nervous and mental diseases . uted to contract more orless vigorously in proportion to the intensity of the current is to be particularly noted that upon allowing the current to passthe response is instantaneous, and that the muscular contraction atonce reaches its maximum and maintains it until the current is modi- ELECTRICAL CONDITIONS. 43 fied. This phenomenon attends stimulation by either the positive ornegative faradic pole or electrode, but the negative causes a slightlystronger effect. If, now, the constant current be substituted, we notice, first of all, thatmild currents applied to the nerve-trunk produce no response. Whenthe current is sufficiently increased it causes, only at the make andbreak, single instantaneous contractions of the innervated muscles, which M. deltoideus N. radialisM. brachial, intern. M. supinator radial, ext. radial, ext. brev. _ M. extensor digit, communis M. extensor indicisM. abductor pollic. extensor pollic. brev. M. inteross. dorsal. I et II. M. triceps (caput longum) M. triceps (caput ex-tern.) M. ulnar, supinat. brev. M. extens. digiti extens. indicis M. extens. poll. long. M. abduct, di^it. min. ) M. inteross. dorsal. Ill/ et IV Fig. 10.—Nerves and motor points in upper extremity. as quickly subside. Looking closer, we notice that the contraction withthe negative make—otherwise the cathodal closing contraction ()—is the first to appear as the current is gradually increased, that nextcomes the positive make, or anodal closing contraction (A. C. C), followedin turn by the positive break, or anodal opening contraction (A. O. C),and then, finally, by the negative break, or cathodal opening contrac-tion (C. O. C). * Further, that by the time we have C. O. C, A. O. C. 44 NERVOUS AND MENTAL DISEASES. will be vigorous, A. C. C. very strong, and C. C. C. produces a con-stant tetanic condition lasting as long as the current flows when onceit is set up bv the make,—a c
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