Journal of Neuroscience, Vol 5, 1881-1885, Copyright © 1985 by Society for Neuroscience
Effect of intrafusal muscle mechanics on mammalian muscle spindle sensitivity
RE Poppele and DC Quick
Sensitivity differences between primary and secondary endings of mammalian
muscle spindles under various conditions of stretch and fusimotor
activation may be due to differences in their respective mechanoelectric
transducers or to mechanical properties of the intrafusal muscle supporting
those endings. This study of isolated cat muscle spindles examines the
strain in individual intrafusal muscle fibers resulting from stretch and
fusimotor stimulation. The degree of local stretch occurring at the sensory
endings under these conditions was measured. The results support the
hypothesis that the sensitivities of primary and secondary endings are
quite similar. They are directly related to the local stretch of the
underlying muscle which may be altered by changes in muscle stress and
stiffness.