Role Of Muscle Spindles Research Articles

Impaired Regulation of Submaximal Force after ACL Reconstruction: Role of Muscle Spindles.

Ongoing motor deficits are routinely present following anterior cruciate ligament (ACL) reconstruction, including the ability to regulate muscle force. While such deficits are known, it is unclear why this occurs. The goal of the current study was to investigate the potential influence of muscle spindle input on submaximal force regulation and muscle activity at the knee in people following ACL reconstruction. Fourteen participants (8 female) who were 6-24 months post-ACL reconstruction and 15 control participants (8 female) undertook submaximal force matching and force modulation tasks before and after 20 min of vibration applied to the patella tendon. Across all tasks, the ACL reconstruction participants were poorer at force matching (P=0.007). The effect of vibration was not significant in either group for the force matching tasks (P=0.06), although there was a reduction in maximum voluntary contraction post-vibration in the control group (P<0.001). The ACL reconstruction group also showed evidence of greater activation of the medial hamstring muscles in comparison to controls (P=0.04). Individuals who have undergone ACL reconstruction have a diminished ability to accurately match and regulate submaximal muscle force, but this does not appear to be related to impaired muscle spindle input. Neuromuscular retraining programs that involve force regulation tasks may be necessary to optimize rehabilitation after ACL reconstruction.

The role of muscle spindles in the development of the monosynaptic stretch reflex

Muscle sensory axons induce the development of specialized intrafusal muscle fibers in muscle spindles during development, but the role that the intrafusal fibers may play in the development of the central projections of these Ia sensory axons is unclear. In the present study, we assessed the influence of intrafusal fibers in muscle spindles on the formation of monosynaptic connections between Ia (muscle spindle) sensory axons and motoneurons (MNs) using two transgenic strains of mice. Deletion of the ErbB2 receptor from developing myotubes disrupts the formation of intrafusal muscle fibers and causes a nearly complete absence of functional synaptic connections between Ia axons and MNs. Monosynaptic connectivity can be fully restored by postnatal administration of neurotrophin-3 (NT-3), and the synaptic connections in NT-3-treated mice are as specific as in wild-type mice. Deletion of the Egr3 transcription factor also impairs the development of intrafusal muscle fibers and disrupts synaptic connectivity between Ia axons and MNs. Postnatal injections of NT-3 restore the normal strengths and specificity of Ia-motoneuronal connections in these mice as well. Severe deficits in intrafusal fiber development, therefore, do not disrupt the establishment of normal, selective patterns of connections between Ia axons and MNs, although these connections require the presence of NT-3, normally supplied by intrafusal fibers, to be functional.

The role of muscle spindles in proprioceptive acuity at the knee, ankle and elbow in individuals with knee osteoarthritis

The role of muscle spindles in proprioceptive acuity at the knee, ankle and elbow in individuals with knee osteoarthritis

Recent advances in the diagnosis and management of diabetic neuropathy

The World Health Organisation estimated that in the year 2000, 150 million people had diabetes mellitus, and it is predicted that this number will rise to 366 million by the year 2030.[1][1] Neuropathy is a common complication of diabetes and is characterised by a progressive loss of peripheral

Clinical Decision Making and Oral Motor Treatments

Clinical Decision Making and Oral Motor Treatments

Human forearm position sense after fatigue of elbow flexor muscles

After a period of eccentric exercise of elbow flexor muscles of one arm in young, adult human subjects, muscles became fatigued and damaged. Damage indicators were a fall in force, change in resting elbow angle and delayed onset of soreness. After the exercise, subjects were asked to match the forearm angle of one arm, whose position was set by the experimenter, with their other arm. Subjects matched the position of the unsupported reference arm, when this was unexercised, with a significantly more flexed position in their exercised indicator arm. Errors were in the opposite direction when the reference arm was exercised. The size of the errors correlated with the drop in force. Less consistent errors were observed when the reference arm was supported. A similar pattern of errors was seen after concentric exercise, which does not produce muscle damage. The data suggested that subjects were using as a position cue the perceived effort required to maintain a given forearm angle against the force of gravity. The fall in force from fatigue after exercise meant more effort was required to maintain a given position. That led to matching errors between the exercised and unexercised arms. It was concluded that while a role for muscle spindles in kinaesthesia cannot be excluded, detailed information about static limb position can be derived from the effort required to support the limb against the force of gravity.

NEUROMUSCULAR CONTROL MECHANISMS IN HUMAN MASTICATION

ABSTRACTi

The role of muscle spindles in constraining motor control

The functional importance of γ-motoneuronal activation during a simple movement task was explored using a computational model of a simplified neuromuscular system. Various schemes of γ-motoneuronal activation were tested under different task conditions. Analysis of the simulation data lend support to the idea that γ-motoneuron activity might be essential for cancelling expected stimuli rather than only for programming servo-controlled equilibrium positions of the limbs. It is concluded that the best performance of a movement is obtained when expected afference is cancelled by γ-activity, thereby allowing for a relatively pure and “noise-free” detection of unexpected loads.

The role of muscle spindles in ankle movement perception in human subjects with diabetic neuropathy

The objective of this study was to develop a quantitative method to assess muscle spindle function. Three groups of subjects were studied: ten young and healthy subjects, 15 older subjects with diabetic neuropathy, and 15 age-matched controls. All subjects performed an ankle-movement matching task with and without muscle vibration. Input from the plantar cutaneous mechanoreceptors was minimized by using a foot-clamping device. The younger subjects tracked the movement very well, but vibration had a significant effect on their performance (P < 0.001). Similar results were seen in the older control subjects, but they were less successful in tracking movement and slightly less affected by vibration. The neuropathic subjects had the most difficulty tracking, and vibration had only a small but still significant effect on their performance. The interaction between the group and the vibration effect was highly significant (P < 0.001), indicating that the performance of the control subjects changed to a greater degree in the presence of vibration than the performance of the subjects with diabetic neuropathy. Muscle spindles are the primary receptors that are involved in the change in tracking performance when vibration is added during an ankle-movement matching task, and we therefore conclude that the procedure described provides a quantitative evaluation of muscle spindle function. The results demonstrate that diabetic neuropathy degrades muscle sensory function, which may contribute to the impaired balance and unsteadiness of gait that has been observed in diabetic neuropathy.

The Mammalian Muscle Spindle

A brief, summarizing description is given of the structure and physiology of the mammalian muscle spindle. The question is addressed, What might be the roles of the three different kinds of intrafusal fibers on which the sensory endings lie? The role of muscle spindles in proprioception and in motor control is discussed.

Role of muscle spindles in lower extremities in breathing during bicycle exercise.

Role of muscle spindles in lower extremities in breathing during bicycle exercise.

THE DUAL SENSORY ROLE OF MUSCLE SPINDLES.

THE DUAL SENSORY ROLE OF MUSCLE SPINDLES.

Contribution of muscle spindle circuits to learning as suggested by training under flaxedil

Fifteen naive cats, while completely paralyzed with Flaxedil, were subjected to a classical conditioning procedure in which tone (CS) was paired with shock to the hindpaw (US). Before each paralytic training session, five test trials with the CS alone were given and the cat was observed for conditioned responses. Six other cats were similarly trained and tested, except that they were paralyzed after completion of each training session. 1. 1. None of the fifteen cats trained while paralyzed showed conditioned motor responses to CS test trials after 500 to 1000 CS-US trials extended over 10 to 20 sessions. In contrast, the six cats trained normally with subsequent paralysis showed conditioned motor responses to the CS test trials after an average of 150 CS-US trials. 2. 2. The development of conditioned changes in cortical activity and pupillary diameter during training under paralysis indicated that the CNS was receptive to the conditioning procedure. 3. 3. Cats with prior training under Flaxedil developed conditioned motor responses during the first ten trials of the initial unparalyzed training session. In contrast, naive cats generally showed no conditioned motor responses until the third training session. 4. 4. The failure of conditioned motor responses to develop during paralytic training and the facilitation of the responses during subsequent normal training are discussed with emphasis upon the possible role of muscle spindles. It is suggested that conditioned responses of gamma motoneurons are established during paralytic training, but proprioceptive feedback is blocked. During subsequent training without paralysis, the added effect of afferent feedback mediated by conditioned and unconditioned responses of the gamma motoneurons may result in an accelerated appearance of the overt conditioned response.

Probleme und Beispiele biologischer Regelung.

Essentially, this book attempts to apply the nomenclature of electronic regulatory mechanisms to the physiologic control of willed motion and of the circulation. The principles of feedback and servomechanisms in technique are considered. They are then discussed in detail in relation to reflex and orderly volitional activity of striated muscles. The role of muscle spindles and tendon organs, for example, is treated as a feedback to anterior horn cells and higher motor centers. Similarly, the author deals with the problems of control of blood pressure, of peripheral blood flow, and of cardiac activity. The author believes that he clarifies and explains physiologic data. I can not share this enthusiasm and have gained little by carefully studying the 210 pages of this book. The writing is in an exceptionally complicated German. It is unusual to call muscle spindles dilator receptors. There are other minor abuses of English terms. However those who