Innervation of extrafusal and intrafusal fibres in snake muscle

Cliff, G. S.; Ridge, R. M. A. P.

doi:10.1113/jphysiol.1973.sp010293

Cited by 15 publications

(8 citation statements)

References 17 publications

(29 reference statements)

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“…Furthermore, we have found that, within one muscle, contraction times vary inversely with motor unit size not only between faster and slower twitch but also among different slower twitch units (R. S. Wilkinson & M. N. Faddis, work in progress). This relation has been reported for another snake muscle (Cliff & Ridge, 1973;Hammond & Ridge, 1978). In contrast, tonic motor units have by far the slowest contraction times (the same as single tonic fibre contraction times, see Wilkinson & Lichtman, 1985a), yet they contain the largest number of fibres.…”

Section: Motor Units In Snake Muscle Size Distribution Of Motor Unitsmentioning

confidence: 76%

“…Motor units were activated by extracellular stimulation of a single nerve terminal (or preterminal axon branch) located with Nomarski optics (Cliff & Ridge, 1973; see Plate 1 A). A glass pipette containing 150 mM-NaCl (tip diameter, 15-25 ,um) was used to deliver 10-100 V, 200 ,/s rectangular voltage pulses of either polarity (whichever had the lowest threshold); an annulus of silver foil in the bath was the return electrode.…”

Section: Methodsmentioning

confidence: 99%

“…The position of the axons comprising the end-plate bands is drawn approximately; however, whether the end-plate is above or below the nerve and the sequence of twitch and tonic muscle fibres, including those within the motor unit (white circles), is precise. Intrafusal muscle fibres, associated with muscle spindles, are known to receive collateral innervation from motor axons in the snake (Cliff & Ridge, 1973), but were not studied.…”

Section: Innervation Pattern Of Twitch Motor Unitsmentioning

confidence: 99%

“…PLATE 1 A, extracellular stimulation pipette (arrow) positioned near a nerve terminal innervating a twitch fibre in the transversus abdominis. Stimulation of one terminal of an axon activated that axon's entire terminal arbour (Cliff & Ridge, 1973). Nomarski contrast photomicrograph; scale bar is 30 /am.…”

mentioning

confidence: 99%

“…Thus they had access to virtually all 200 tonic end-plates in the muscle. Furthermore, each of the five to seven end-plates on one tonic fibre seemed to be an independent target; an axon's strength of innervation at one end-plate ( (Cliff & Ridge, 1973). Nomarski contrast photomicrograph; scale bar is 30 /am.…”

mentioning

confidence: 99%

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Properties of motor units in the transversus abdominis muscle of the garter snake.

Lichtman

Wilkinson

1987

The Journal of Physiology

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1. The organization of motor units in the single‐fibre‐thick transversus abdominis muscle of the garter snake has been studied. This small segmental muscle (60‐100 fibres) contains three distinct fibre types (faster twitch, F; slower twitch, S; and tonic, T) which are predominantly arranged in the repeating pattern F, T, S, T, F, T, etc. 2. Motor‐unit maps were obtained by activating an individual motor axon and identifying all of the muscle fibres innervated by that axon, using either the activity‐induced uptake of extracellular marker molecules to label presynaptic terminals of the stimulated axon, or systematic intracellular recording to identify muscle fibres activated by the axon. 3. Each muscle contained three types of motor units (F, T and S) that corresponded to the three types of fibres. All of the muscle fibres in a motor unit were of the same type. Each segmental muscle contained approximately the same number of motor units: one to two faster twitch, three to four slower twitch, and three tonic. 4. Each motor unit was dispersed widely throughout the muscle. Fibres within a motor unit were neither clustered nor anticlustered. This suggests that despite the fact that axons are constrained to innervate fibres of the appropriate type, the distribution of each motor unit does not generate the alternating pattern of fibre types. 5. In several experiments, all of the twitch motor units in one segmental component of the muscle were mapped. The projection of any one axon appeared random not only with respect to the muscle's fibre type pattern, but also with respect to the innervation supplied by other axons. 6. Twitch motor units were arranged according to a hierarchy of sizes. In each muscle examined, the largest motor unit was faster twitch; a single faster twitch motor axon usually innervated all of the faster twitch fibres in the muscle (fourteen to twenty‐four fibres). This was followed by three to four slower twitch motor units which varied in size from eight to ten fibres to very small motor units containing only four to five fibres. 7. Each tonic motor axon innervated an average of ninety‐three end‐plates per segmental muscle. The relatively large size of tonic motor units compared to twitch motor units is related to the ability of tonic muscle fibres to retain polyneuronal innervation into adulthood, both by providing five to seven end‐plate sites per fibre, and by allowing terminal boutons from different tonic motor axons to co‐innervate the same end‐plate.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Motor Units In Snake Muscle Size Distribution Of Motor Unitsmentioning

confidence: 76%

Section: Methodsmentioning

confidence: 99%

Section: Innervation Pattern Of Twitch Motor Unitsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Properties of motor units in the transversus abdominis muscle of the garter snake.

Lichtman

Wilkinson

1987

The Journal of Physiology

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Neurologic Degeneration Associated With Nitrous Oxide Anesthesia in Patients With Vitamin B12 Deficiency

Flippo

Holder²

1993

Arch Surg

138

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Vitamin B12 (cyanocobalamin) is an integral component of two biochemical reactions in man: the conversion of L-methylmalonyl coenzyme A into succinyl coenzyme A and the formation of methionine by methylation of homocysteine. The transmethylation reaction is essential to DNA synthesis and to the maintenance of the myelin sheath by the methylation of myelin basic protein. Active vitamin B12 contains cobalt in its reduced form (Co+). Nitrous oxide produces irreversible oxidation to the Co++ and Co forms that renders vitamin B12 inactive. Five cases (four from the literature and one new case) are presented in which patients unsuspected of having vitamin B12 deficiency developed subacute combined degeneration of the spinal cord following nitrous oxide anesthesia. Patients with vitamin B12 deficiency are exceedingly sensitive to neurologic deterioration following nitrous oxide anesthesia. If unrecognized, the neurologic deterioration becomes irreversible and may result in death.

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The Physiology of Motor Units in Mammalian Skeletal Muscle

Lewis

1981

Motor Coordination

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Innervation of extrafusal and intrafusal fibres in snake muscle

Cited by 15 publications

References 17 publications

Properties of motor units in the transversus abdominis muscle of the garter snake.

Properties of motor units in the transversus abdominis muscle of the garter snake.

Neurologic Degeneration Associated With Nitrous Oxide Anesthesia in Patients With Vitamin B12 Deficiency

The Physiology of Motor Units in Mammalian Skeletal Muscle

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