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Motor Neurological Examination of the Hand and Upper Limb
Published in J. Terrence Jose Jerome, Clinical Examination of the Hand, 2022
The basic step of the reflex is that when a sudden stretch of the muscle is caused, a reflex is initiated, which results in the muscle contracting immediately. This is primarily to prevent undue stretching of the muscle and hence avoiding injury to the muscle fibres. This reflex contraction of the muscle that has been stretched is called the stretch reflex. The mechanism by which this stretch reflex occurs, involves two simple neuron arcs.
Functional Neurology
Published in James Crossley, Functional Exercise and Rehabilitation, 2021
When spindles detect a rapid change in muscle length, due to excessive stretch, they trigger a spinal reflex, generating a muscular contraction. This is known as the stretch reflex. A popular illustration of the stretch reflex is the ‘knee-jerk’. When a GP taps the underside of the knee, muscle spindles detect rapid stratch caused by the blow to the patellar tendon stretch, activating the quadricep and making the foot leap into the air.
Spinal Cord and Reflexes
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
Although the stretch reflex is encountered in most skeletal muscle, it is particularly strong in antigravity muscles, where it would tend to automatically maintain posture, this being an important function of the stretch reflex. The antigravity muscles of the back and legs are extensor muscles because the joints involved will tend to flex, or buckle, under the influence of gravity. Any such movement will stretch the extensor muscles, thereby eliciting a stretch reflex that would restore posture. The antigravity muscles of the arm, however, are the flexors, not the extensors because gravity would tend to extend the arm joints. The monosynaptic component of the stretch reflex can play an important physiological role during fast movements or for a fast readjustment of posture upon loss of balance. For example, in jumping from a moderate height to land with both feet on the ground, if the stiffness of the knee is insufficient, the knee extensors would be rapidly stretched, and the monosynaptic component of the reflex would produce a fast contraction of the extensors that would prevent the buttocks from hitting the ground. The monosynaptic component of the stretch reflex is fast, having a response time of few tens of milliseconds because: (i) there is only one synaptic delay, (ii) the Ia fibers are the largest and hence the fastest conducting peripheral fibers, and (iii) the monosynaptic connections of the Ia fibers are on the larger α-motoneurons, which in turn have large, fast conducting axons.
Typical Development of Finger Position Sense From Late Childhood to Adolescence
Published in Journal of Motor Behavior, 2023
Jinseok Oh, Arash Mahnan, Jiapeng Xu, Hannah J. Block, Jürgen Konczak
Proprioception and motor control are intricately linked. Proprioceptive afferents are used by the nervous system to regulate muscle tone, spinal stretch reflexes, and postural reflexes. Moreover, cerebro-cerebellar and somatosensory motor cortical networks process proprioceptive signals for voluntary motor control. It is firmly established that the networks undergo structural and functional changes during development (Cadwell et al., 2019; Van Essen et al., 2018), yet the exact neural mechanisms underlying proprioceptive development in humans are still not fully delineated. It would be useful to know what features of neural development are consistent with behavioral markers of proprioceptive development such as those reported here. It is unlikely that morphological changes in proprioceptive mechanoreceptors can explain such perceptual development, because muscle spindles are not going through significant morphological changes after 3 years of age in humans (Osterlund et al., 2011). However, there is evidence that an age-related increased sensitivity of the muscle spindles as stretch reflex responses increase across age in children from 7 to 11 years in TD (Grosset et al., 2007). Improved muscle spindle sensitivity will result in afferent signals that allow the proprioceptive system to differentiate between smaller differences in finger position, which could translate in more precise perceptual judgments.
Effect of inhibitory kinesiotaping on spasticity in patients with chronic stroke: a randomized controlled pilot trial
Published in Topics in Stroke Rehabilitation, 2022
Mahdad Mehraein, Zahra Rojhani- Shirazi, Ahmad Zeinali Ghotrom, Nasrin Salehi Dehno
In a recent study by Puce et al. (2021), the effect of KT on knee extensor spasticity was investigated in para-swimmers.54 In line with our study, they reported a significant decrease in the amplitude of stretch reflex 48 hours after KT, but MAS score did not change following KT.54 Despite the similarity between our results, they examined athletes and measured spasticity by stretch reflex. The H-reflex and stretch reflex have the same spinal circuitry.55 However, for H-reflex, Ia afferent axons are excited electrically and stretch reflex is elicited by the mechanical stimulation of group Ia and II afferent axons.55 Hence, our study is the first to highlight the specific effect of KT on the reflex component of muscle tone, which is spasticity in patients with stroke.
The effectiveness of interventions targeting spasticity on functional clinical outcomes in patients with multiple sclerosis: a systematic review of clinical trials
Published in European Journal of Physiotherapy, 2022
Merziye Ergul, Afsun Nodehi Moghadam, Rachel Soh
Pharmacological agents and non-pharmacological interventions are used in management of spasticity. Pharmacological treatment includes anti-spasticity medications, such as baclofen, botulinum toxin, diazepam, dantrolene and tizanidine [6,7]. They have limited efficiency and systemic side effects, such as cognitive impairment and muscle weakness [8]. Physiotherapy interventions for spasticity management which are currently being used include a diverse range of interventions, such as exercise therapy, electrotherapy, electromagnetic therapy, massage and orthotics. As a non-pharmacological intervention, the primary aim of physiotherapy interventions for reducing spasticity is to reduce stretch reflex excitability through decreasing excessive alpha-motor neuron activity and hypersensitivity of muscle spindles. The secondary aims are prevention and reducing consequences of spasticity, such as muscle and soft tissue contractures, limb stiffness, decreased range of motion, pain, gait problems, functional limitations and decreased quality of life [9].