stretch reflex

physiology

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July 14, 2026

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The stretch reflex is a physiological response where a muscle contracts when it is stretched. This reflex is mediated by muscle spindles, which are sensory receptors within the muscle that detect changes in length and tension. When a muscle is suddenly stretched, the muscle spindles are activated, sending signals to the spinal cord. This triggers a motor response that causes the stretched muscle to contract, helping to maintain posture and balance. This reflex arc is monosynaptic, meaning it involves a direct connection between the sensory neuron and the motor neuron, allowing for a rapid response. The stretch reflex is a fundamental part of how the nervous system controls movement and maintains muscle tone.1234

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human nervous system
Stretch reflexes
Primary afferent fibers are responsible for the stretch reflex, in which pulling the tendon of a muscle causes the muscle to contract. As noted above, the basis for this simple spinal reflex is a monosynaptic excitation of the motor neurons of the stretched…
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Primary afferent fibers are responsible for the stretch reflex, in which pulling the tendon of a muscle causes the muscle to contract. As noted above, the basis for this simple spinal reflex is a monosynaptic excitation of the motor neurons of the stretched…
Read More