title: [Is the origin of the F-wave dependent on the magnitude of the motor unit?].
abstract: 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.
authors.affiliation: Neurologische Klinik und Poliklinik, Universität Bonn.
authors.forename: K
authors.initials: K
authors.lastname: Wohlfarth
authors.forename: R
authors.initials: R
authors.lastname: Dengler
authors.forename: A
authors.initials: A
authors.lastname: Kossev
authors.forename: J
authors.initials: J
authors.lastname: Elek
authors.forename: M
authors.initials: M
authors.lastname: Schubert
authors.forename: W
authors.initials: W
authors.lastname: Wolf
mesh_terms: D000328:Adult; D004576:Electromyography; D006801:Humans; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D012016:Reference Values
vernacular_title: Ist die F-Wellen-Entstehung abhängig von der Grösse der motorischen Einheiten?