Nervous and mental diseases . or points in upper extremity. mild currents applied to the nerve-trunk produce no response. Whenthe current is suflficiently increased it causes, only at the make and 44 NERVOUS AND MENTAL DISEASES. break, single instantaneous contractions of the innervated muscles, whichas 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
Nervous and mental diseases . or points in upper extremity. mild currents applied to the nerve-trunk produce no response. Whenthe current is suflficiently increased it causes, only at the make and 44 NERVOUS AND MENTAL DISEASES. break, single instantaneous contractions of the innervated muscles, whichas 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. 0. C, A. O. C, 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. M. triceps (caput longum) M. triceps (caput ex-tern.) M. ulnar, supinat. brev. M. extens. digiti extens. indicis M. extens. poll. long. - M. abduct, digit, min. M, inteross. dorsal. IlletIV Fig. 10.—Nerves and motor points in upper extremity. 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 condition called cathodal closing tetanus(C. C. T.). The contractions from stimulating the nerve-trunk thus in healthappear in the following order: C. C. C, A. C. C, A. O. C, andC. O. C, and this indicates their intensity in a decreasing order. The ELECTRICAL CONDITIONS. 45 important point to constantly bear in mind is that the negative makecontraction through healthy nerves is stronger than the positive, Thisfact is thus formulated: >A. In using the constant or galvanic current one must be sure of the polewith which
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