title: Shared motor innervation between dynamic and static intrafusal muscle fibers in the monkey.
abstract: Distributions of 25 motor axons to 60 intrafusal muscle fibers of 10 poles of monkey spindle were reconstructed from serial 1 micron thick transverse sections of lumbrical muscles. About 44% of motor axons co-innervated two or more types of intrafusal fiber. The (dynamic) bag1 fiber shared motor innervation with the (static) bag2 or chain fibers in about 50% of spindle poles. Activation of single intrafusal fibers independent of the other fibers of the same intrafusal bundle occurs to a lesser degree in spindles of monkeys than in spindles of cats. Functional implications of this pattern of motor innervation are discussed.
authors.forename: J
authors.initials: J
authors.lastname: Kucera
mesh_terms: D000818:Animals; D001369:Axons; D002415:Cats; D008252:Macaca fascicularis; D009046:Motor Neurons / Q000166:cytology*; D009470:Muscle Spindles / Q000648:ultrastructure*; D009132:Muscles / Q000294:innervation*; D051381:Rats; D013045:Species Specificity