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This Article Full Text Full Text (PDF) All Versions of this Article: 571/2/489    most recent jphysiol.2005.102731v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Durbaba, R. Articles by Rawlinson, S. Search for Related Content PubMed PubMed Citation Articles by Durbaba, R. Articles by Rawlinson, S. Related Collections Integrative

¹ Department of Clinical Neuroscience, Division of Neuroscience & Mental Health, Imperial College London, Charing Cross Campus, St Dunstan's Road, London W6 8RP, UK

Recordings have been made from 127 single muscle spindle afferents from the longissimus lumborum muscles of anaesthetized cats. They have been characterized by their responses to passive muscle stretch and the effects of succinylcholine (SCh) and by their sensitivity to vibration. The use of SCh permitted the assessment for each afferent of the influence of bag₁ (b₁) and bag₂ (b₂) intrafusal muscle fibres. From this, on the assumption that all afferents were affected by chain (c) fibres, they were classified in four groups: b₁b₂c (41.9%), b₂c (51.4%), b₁c (1.3%) and c (5.4%). All the afferents with b₁ influence were able to respond one to one to vibration at frequencies above 100 Hz and were considered to belong to primary endings. On the basis of the vibration test, 64% of the b₂c type afferents appeared to be primaries and 36% secondaries. Of the units classified as primaries, 41% were designated as b₂c and would not therefore be able to respond to dynamic fusimotor activity. The significance of this relatively high proportion of b₂c-type spindle primary afferents is discussed in relation to the specialized postural function of the back muscles.

(Received 30 November 2005; accepted after revision 7 January 2006; first published online 12 January 2006)
Corresponding author A. Taylor: Department of Clinical Neuroscience, Division of Neuroscience and Mental Health, Imperial College London, Charing Cross Campus, St Dunstan's Road, London W6 8RP, UK. Email: t.taylor{at}imperial.ac.uk

This article has been cited by other articles:

				R. Durbaba, A. Taylor, P. H. Ellaway, and S. Rawlinson Spinal projection of spindle afferents of the longissimus lumborum muscles of the cat J. Physiol., April 15, 2007; 580(2): 659 - 675. [Abstract] [Full Text] [PDF]