[Is the origin of the F-wave dependent on the magnitude of the motor unit?].
It is still unknown why only few motor units (MUs) generate F-waves in response to supramaximal stimulation of a motor nerve. Therefore we investigated whether the F wave production might depend on MU-size. According to the size principle of Henneman we used the twitch force as indirect measure of MU-size. MU twitch force was determined applying the technique of intramuscular microstimulation of single motor axons. 127 MUs were analysed in 16 normal subjects. F-waves were observed in 35 MUs (27%). It was found that MUs of different sizes produced F-waves with approximately the same probability. Obviously size is not a relevant factor for the capability of a MU to produce F-waves. Only the few very large MUs of a pool may have an increased tendency to produce F-waves because four of five MUs with extremely large twitch forces (> 70 mN) generated F-waves.
Wohlfarth
K
K
Neurologische Klinik und Poliklinik, Universität Bonn.
Dengler
R
R
Kossev
A
A
Elek
J
J
Schubert
M
M
Wolf
W
W
D000328:Adult; D004576:Electromyography; D006801:Humans; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D012016:Reference Values
Ist die F-Wellen-Entstehung abhängig von der Grösse der motorischen Einheiten?