Observations on the primary sensory ending of tenuissimus muscle spindles in the cat

1986 ◽  
Vol 246 (2) ◽  
pp. 309-319 ◽  
Author(s):  
R. W. Banks
Keyword(s):  
Muscle Spindles ◽  
Sensory Ending

Human muscle spindles: fine structure of the primary sensory ending

1975 ◽  
Vol 4 (6) ◽  
pp. 675-695 ◽  
Author(s):  
William R. Kennedy ◽  
Henry deF Webster ◽  
Kwon Sang Yoon
Keyword(s):  
Fine Structure ◽  
Muscle Spindles ◽  
Human Muscle ◽  
Sensory Ending

Further morphological and electrophysiological studies on snake muscle spindles

1982 ◽  
Vol 47 (5) ◽  
pp. 810-826 ◽  
Author(s):  
Y. Fukami
Keyword(s):  
Action Potential ◽  
Intercellular Space ◽  
Muscle Spindles ◽  
Ruthenium Red ◽  
Negative Potential ◽  
Bathing Solution ◽  
Longitudinal Diffusion ◽  
Sensory Ending ◽  
Intrafusal Fiber ◽  
Nerve Impulses

1. Electron microscope studies using ruthenium red, horseradish peroxidase, and colloidal lanthanum disclosed a feature characteristic of the snake spindle capsule: it consists of a single layer of flattened cells connected in series, each of which forms a cylinder enclosing the intrafusal fiber. 2. In intact spindles none of the markers penetrated the capsule. The diffusion barrier appeared to be located along the intercellular space near the inner surface of the capsule layer. Through the openings at the ends of the capsule the marker gained access to the periaxial space, but only for a limited distance. 3. Through a punctured hole in the capsule, ruthenium red had access to the periaxial space, disclosing a dense network consisting of fine filaments and granular structures. Since this space was also shown to contain alcian blue-positive substrate, the network may represent acid mucopolysaccharide (probably hyaluronic acid + protein molecules), which may account for the observed limited longitudinal diffusion of this dye in the periaxial space. The intercellular space between the intrafusal fiber, the sensory ending, and the satellite cell was filled with ruthenium red, and no special junction was found between these cells. 4. Using glass microelectrodes, potential profiles across the sensory region of muscle spindles of the snake were examined. 5. When the electrode was advanced through the capsular region, two steps of negative potential were usually observed. The first negative step of 5-10 mV was confirmed by fluorescent dye injection to be due to penetration of the capsule. The second larger step of 40-60 mV negative to the bathing solution was demonstrated by the dye injection to be due to penetration of the intrafusal fiber. Occasionally, a negative potential of 20-30 mV relative to the bathing solution was also recorded. This potential, characterized by small spikelike potentials occurring in synchrony with nerve impulses, was considered to be due to penetration of the sensory ending. 6. both the capsule and the intrafusal fiber showed rectification to injected currents. From input resistance, input capacitance and surface area specific resistance and capacitance were estimated with some assumptions to be 4.1-4.8 k omega . cm2 and 5.1-14.3 micro F/cm2 for the capsule, and 1.1-2.8 k omega . cm2 and 11-23 micro F/cm2 for the intrafusal fiber. The intrafusal fiber of short-capsule spindles lacked an action potential, whereas that of long-capsule spindles responded with an all-or-none action potential to depolarizing current. 7. In about half of the short-capsule spindles examined (8/15), current injected through an intracellular electrode in the intrafusal fiber neither initiated impulses in the afferent axon nor affected background nerve activity. The rest of the spindles responded to depolarizing current with initiation of nerve impulses and concomitant maintained contraction of the intrafusal fiber during applied current...

Absence of Muscle Spindles in Human Facial Muscles

2004 ◽  
Vol 35 (03) ◽  
Author(s):  
PP Urban ◽  
J Bohl ◽  
L Abrao ◽  
E Stofft
Keyword(s):  
Muscle Spindles ◽  
Facial Muscles

scholarly journals The path from trigeminal asymmetry to cognitive impairment: a behavioral and molecular study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maria Paola Tramonti Fantozzi ◽  
Giulia Lazzarini ◽  
Vincenzo De Cicco ◽  
Angela Briganti ◽  
Serena Argento ◽  
...  
Keyword(s):  
Pupil Size ◽  
Muscle Spindles ◽  
Molecular Study ◽  
Contralateral Side ◽  
Acute Effects ◽  
Adult Rats ◽  
Afferent Inputs ◽  
Acute And Chronic Effects ◽  
The Brain ◽  
Mandibular Branch

AbstractTrigeminal input exerts acute and chronic effects on the brain, modulating cognitive functions. Here, new data from humans and animals suggest that these effects are caused by trigeminal influences on the Locus Coeruleus (LC). In humans subjects clenching with masseter asymmetric activity, occlusal correction improved cognition, alongside with reductions in pupil size and anisocoria, proxies of LC activity and asymmetry, respectively. Notably, reductions in pupil size at rest on the hypertonic side predicted cognitive improvements. In adult rats, a distal unilateral section of the trigeminal mandibular branch reduced, on the contralateral side, the expression of c-Fos (brainstem) and BDNF (brainstem, hippocampus, frontal cortex). This counterintuitive finding can be explained by the following model: teeth contact perception loss on the lesioned side results in an increased occlusal effort, which enhances afferent inputs from muscle spindles and posterior periodontal receptors, spared by the distal lesion. Such effort leads to a reduced engagement of the intact side, with a corresponding reduction in the afferent inputs to the LC and in c-Fos and BDNF gene expression. In conclusion, acute effects of malocclusion on performance seem mediated by the LC, which could also contribute to the chronic trophic dysfunction induced by loss of trigeminal input.

Computer Simulation of the Responses of Human Motoneurons to Composite 1A EPSPS: Effects of Background Firing Rate

1997 ◽  
Vol 77 (1) ◽  
pp. 405-420 ◽  
Author(s):  
Kelvin E. Jones ◽  
Parveen Bawa
Keyword(s):  
Computer Simulation ◽  
Firing Rate ◽  
Time Course ◽  
Current Model ◽  
Response Probability ◽  
Muscle Spindles ◽  
Excitatory Postsynaptic Potential ◽  
Biophysical Properties ◽  
Rhythmic Firing ◽  
The Relationship

Jones, Kelvin E. and Parveen Bawa. Computer simulation of the responses of human motoneurons to composite 1A EPSPS: effects of background firing rate. J. Neurophysiol. 77: 405–420, 1997. Two compartmental models of spinal alpha motoneurons were constructed to explore the relationship between background firing rate and response to an excitatory input. The results of these simulations were compared with previous results obtained from human motoneurons and discussed in relation to the current model for repetitively firing human motoneurons. The morphologies and cable parameters of the models were based on two type-identified cat motoneurons previously reported in the literature. Each model included five voltage-dependent channels that were modeled using Hodgkin-Huxley formalism. These included fast Na+ and K+ channels in the initial segment and fast Na+ and K+ channels as well as a slow K+ channel in the soma compartment. The density and rate factors for the slow K+ channel were varied until the models could reproduce single spike AHP parameters for type-identified motoneurons in the cat. Excitatory synaptic conductances were distributed along the equivalent dendrites with the same density described for la synapses from muscle spindles to type-identified cat motoneurons. Simultaneous activation of all synapses on the dendrite resulted in a large compound excitatory postsynaptic potential (EPSP). Brief depolarizing pulses injected into a compartment of the equivalent dendrite resulted in pulse potentials (PPs), which resembled the compound EPSPs. The effects of compound EPSPs and PPs on firing probability of the two motoneuron models were examined during rhythmic firing. Peristimulus time histograms, constructed between the stimulus and the spikes of the model motoneuron, showed excitatory peaks whose integrated time course approximated the time course of the underlying EPSP or PP as has been shown in cat motoneurons. The excitatory peaks were quantified in terms of response probability, and the relationship between background firing rate and response probability was explored. As in real human motoneurons, the models exhibited an inverse relationship between response probability and background firing rate. The biophysical properties responsible for the relationship between response probability and firing rate included the shapes of the membrane voltage trajectories between spikes and nonlinear changes in PP amplitude during the interspike interval at different firing rates. The results from these simulations suggest that the relationship between response probability and background firing rate is an intrinsic feature of motoneurons. The similarity of the results from the models, which were based on the properties of cat motoneurons, and those from human motoneurons suggests that the biophysical properties governing rhythmic firing in human motoneurons are similar to those of the cat.

On the regional distribution of muscle spindles

1989 ◽  
Vol 12 (4) ◽  
pp. 666-666
Author(s):  
John B. Munson ◽  
Robert C. Foehring
Keyword(s):  
Regional Distribution ◽  
Muscle Spindles
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