The responses of muscle spindles in sheep extraocular muscles.

Browne, J. S. L.

doi:10.1113/jphysiol.1975.sp011104

Cited by 20 publications

(12 citation statements)

References 16 publications

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“…Eight units from muscle spindles (2 from LR, 2 SO, 1 SR, 1 MR, 1 IR, 1 IO) were identified by their low threshold to muscle stretch and by their response to tetanic stimulation of the motor nerve [4]. The discharge frequency of the proprioceptive units and tension of the muscle to which the unit belonged were measured at different static muscle lengths from Lr -2 to Lr + 8.…”

Section: Resultsmentioning

confidence: 99%

Effect of botulinum toxin on extraocular muscle proprioception

et al. 1989

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Injections of botulinum toxin type A (BoTox) in one extraocular muscle (EOM) induce long lasting paretic lengthening of the muscle permitting realignment to occur in strabismus, while eye movements appear to be unaffected after the transitory period of induced paresis. It has been hypothesized a BoTox-induced change in the spindle discharge of EOMs to explain the effect in EOM length. In decerebrate lambs and goats, first order neurons of eye muscle spindles were identified in a cellular pool located in the medial dorsolateral portion of the semilunar ganglion. The belly of the muscle to which the recorded unit belonged was infiltrated with BoTox. A decrease in afferent discharge of the spindle and in its stretch sensitivity was observed. This effect began 10-15 minutes after the injection. There was no corresponding decrease in muscle tension during the first 45 minutes. This finding suggests that the block of release of acetylcholine at motor endings is earlier and more efficacious in gamma- than in alpha-motoneurons. As a result of the proprioceptive input reduction, an unbalance between the agonist and antagonist muscles should occur favouring the ocular realignment.

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Section: Resultsmentioning

confidence: 99%

Effect of botulinum toxin on extraocular muscle proprioception

et al. 1989

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“…On the basis of such effects of SCh on the intrafusal fibers in muscle spindles, many investigators have attempted to clarify the functional and morphological significance of muscle spindles, including their afferent contacts on intrafusal fibers, the classification of their afferents, and their central projections (e.g., Cody et al, 1972;Browne, 1975;Dutia, 1980;Inoue et al, 1981;Price and Dutia, 1987;Scott, 1988Scott, , 1990Scott, , 1991Taylor et al, 1992aTaylor et al, ,b, 1993Carr et al, 1996). Although it has been generally agreed that muscle spindle afferents from the limb or neck muscles are mainly classified into primary and secondary endings on the basis of their conduction velocities, fiber diameters, and dynamic and static sensitivities or other functional properties to stretch responses, the position of the dividing line between the two populations is somewhat variable among different muscles (e.g., Hunt, 1951;Matthews, 1963Matthews, , 1972Crowe and Matthews, 1964;Koeze, 1968Koeze, , 1973Lennerstrand, 1968;Matthews and Stein, 1969;Browne, 1975;Cheney and Preston, 1976;Richmond and Abrahams, 1979;Wei et al, 1986;Price and Dutia, 1987;Scott, 1990;Carr et al, 1996). However, jaw muscle and extraocular muscle spindle afferents may not be classified into primary and secondary endings on the basis of their fiber diameters, conduction velocities, as well as from dynamic sensitivities or other parameters to stretch responses, because of the lack of any clear evidence of a bimodal distribution of the values of DI (Browne, 1975;Inoue et al, 1981;Shigenaga et al, 1990;Taylor et al, 1992a).…”

Section: Classification Of Spindle Afferentsmentioning

confidence: 99%

Central distribution of synaptic contacts of primary and secondary jaw muscle spindle afferents in the trigeminal motor nucleus of the cat

et al. 1998

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Little is known about the differences of the terminations of group Ia and group II afferents within the brainstem or spinal cord. The present study was performed to classify cat jaw muscle spindle afferents by the use of succinylcholine (SCh) and to examine the morphological characteristics of the physiologically classified afferents at the light and electron microscopic levels through the use of the intra-axonal horseradish peroxidase (HRP) injection technique. The effects of SCh on stretch responses of 119 jaw muscle spindle afferents from the masseter were examined. The SCh converted the single skew distribution of the values for dynamic index (DI) into a bimodal one. Fifty-eight and 61 afferents were classified as group Ia and group II afferents, respectively. The central projections of 17 intra-axonally stained afferents (10 group Ia and 7 group II afferents) were examined. The spindle afferents terminated mainly in the supratrigeminal nucleus (Vsup), region h, and the dorsolateral subdivision of trigeminal motor nucleus (Vmo.dl) but differed in the pattern of projections of group Ia and group II afferents. The proportion of group Ia afferent terminals was higher in Vmo.dl but lower in Vsup than that of group II afferents. In Vmo.dl, the proportion of group Ia afferent terminals was higher in the central region but lower in the more outer regions than that of group II afferents. The ultrastructure of serially sectioned afferent boutons (63 group Ia and 72 group II boutons) also was examined. The boutons from the two groups were distributed widely from the soma to small-diameter dendrites, but the frequency of synaptic contacts on proximal dendrites was higher in group Ia than group II afferents. The present study provides evidence that the two groups of jaw muscle spindle afferents differ in their central projection and the spatial distribution of their synaptic contacts on Vmo.dl neurons.

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“…Afferent discharges in nerves of EOMs present the classical features of the muscle spindles responses, whether or not animals are provided with muscle spindles (Bach-y-Rita and Murata, 1964;Bach-y-Rita and Ito, 1966b;Browne, 1975). However, until now, the trigger features and discharges of the different muscle receptors have never been analysed.…”

Section: Functional Considerationsmentioning

confidence: 99%

Identification of nerve endings in cat extraocular muscles

Billig

Delmas²,

Buisseret

1997

Anat. Rec.

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Background The aim of the present study was to identify the varieties of sensory and motor nerve endings in cat extraocular muscles. Methods Sensory terminals were identify by injecting neuronal tracers (fast blue, biocytin, or peroxidase) into the trigeminal ganglion, which contains the sensory cells innervating the eye muscles. Motor terminals were identified by injections of horseradish peroxidase or DiI, a fluorescent carbocyanin dye, into either the oculomotor nerve or the IIIrd nuclei. Results Injections into the trigeminal ganglion anterogradely labelled three types of sensory nerve endings for each neuronal tracer used: (1) the well‐known “palisade” endings at the myotendinous junction of each extraocular muscle; (2) “compact” endings consisting of a dense terminal arborization extending up to 60 μm in length on striated muscle fibres 10‐15 μm in diameter; and (3) “complex” endings on muscle fibres 15‐20 μm in diamter. The complex ending issued from multiple collateral branches of the parent nerve fibre, which stretched and turned around the muscle fibre and gave off numerous terminal varicosities over a distance of about 140 μm. The sensory complex and compact endings presented strong similarities with some “atypical muscle spindles” previously described. In addition to the classic motor “plate” and “grape,” we found evidence for the existence of motor “spiral” endings with each tracer. Conclusions The sensory nature of the palisade endings was demonstrated, and two other types of sensory terminals were identified and described. The spiral nerve terminals were demonstrated to be motor in nature, and a possible function in the microsaccadic movements associated with fixation is suggested. Anat. Rec. 248:566‐575, 1997. © 1997 Wiley‐Liss, Inc.

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The responses of muscle spindles in sheep extraocular muscles.

Cited by 20 publications

References 16 publications

Effect of botulinum toxin on extraocular muscle proprioception

Effect of botulinum toxin on extraocular muscle proprioception

Central distribution of synaptic contacts of primary and secondary jaw muscle spindle afferents in the trigeminal motor nucleus of the cat

Identification of nerve endings in cat extraocular muscles

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