On the branching of motoneurons.
Innervation ratios were estimated for motor units supplying superficial lumbrical muscles of the cat after assigning units to one of three types, FF/FI, FR, and S, and estimating their axonal conduction velocity, based on published data. Similarly, unit tensions were converted to muscle fiber number using published values for specific tension and fiber cross-sectional area. A relation was established between axonal area of cross-section and number of fibers innervated which was matched reasonably well by a model of a branching motoneuron with preterminal diameter of 4.28 microm and a daughter-to-parent ratio of 1.48 at each level of branching. It is proposed that the main features of the model are likely to apply to all motoneurons.
Morgan
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DL
Department of Electrical and Computer Systems Engineering, Monash University, Clayton, Victoria, Australia.
Proske
U
U
D000818:Animals; D001369:Axons / Q000502:physiology; D002415:Cats; D009046:Motor Neurons / Q000502:physiology* / Q000648:ultrastructure*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation*; D009431:Neural Conduction / Q000502:physiology