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. 1979 Feb:287:329-36.
doi: 10.1113/jphysiol.1979.sp012662.

Voluntary activation of spindle endings in human muscles temporarily paralysed by nerve pressure

D Burke, K E Hagbarth, N F Skuse

Voluntary activation of spindle endings in human muscles temporarily paralysed by nerve pressure

D Burke et al. J Physiol. 1979 Feb.

Abstract

1. In normal human subjects, the afferent activity from muscle spindle endings in the pretibial muscles was recorded while a pressure block was applied to the peroneal nerve proximally in the popliteal fossa. 2. In five of ten blocks, spindle activity increased in attempted isometric voluntary contractions when the receptor-bearing muscles were completely paralysed. In the remaining five blocks, voluntary effort still increased spindle activity when maximum voluntary power was reduced by more than 90%, but the ability to activate spindles voluntarily was lost with or slightly before block of the last motor units. When the ability to activate spindle endings in an attempted voluntary contraction was lost sympathetic efferent fibres remained unblocked. 3. It is concluded that the fusimotor effects seen during a voluntary contraction are mediated by myelinated fibres of small calibre which probably innervate intrafusal structures exclusively (gamma fusimotor fibres). There is no necessity to postulate that skeleto-fusimotor (beta) fibres are responsible for the tight 'alpha-gamma co-activation' seen in man during voluntary contractions.

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References

    1. J Neurophysiol. 1975 May;38(3):560-71 - PubMed
    1. J Neurol Neurosurg Psychiatry. 1975 Jul;38(7):625-35 - PubMed
    1. J Physiol. 1975 Dec;253(2):565-82 - PubMed
    1. J Neurol Neurosurg Psychiatry. 1975 Dec;38(12):1143-53 - PubMed
    1. J Neurophysiol. 1975 Nov;38(6):1390-4 - PubMed

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