THE HUMAN ELECTROMYOGRAM IN RESPONSE TO NERVE STIMULATION AND THE CONDUCTION VELOCITY OF MOTOR AXONS: Studies on Normal and on Injured Peripheral Nerves

Abstract

ELECTROMYOGRAPHIC technics can be employed to obtain a quantitative measure of the functional impairment in man resulting from injury to peripheral nerve fibers or from other causes which prevent the passage of impulses along motor nerve fibers or across neuromuscular junctions. In the studies of nerve trauma to be described in this paper, the damaged nerve was activated by electrical stimuli delivered through the skin. The stimulating shocks were strong enough to activate all the excitable skeletomotor fibers in the nerve. The muscle action potential was recorded through small electrodes on the skin overlying appropriate muscles; this was the combined potential of many individual muscle fibers. The magnitude of this response was therefore determined, in part, by the number of muscle fibers which were functionally innervated and could, accordingly, be used to detect changes in this number, for example, during regeneration of an injured nerve. In addition, the conduction velocities