Stretch Reflex ; guyton and hall physiology:indu khurana physiology

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Aug 30, 2026

Stretch Reflex — Description The stretch reflex is a monosynaptic spinal reflex in which stretching of a skeletal muscle produces reflex contraction of the same muscle. Mechanism: 1. Stretching of the muscle activates muscle spindles. 2. Ia sensory afferent fibers carry impulses to the spinal cord. 3. The Ia fiber makes a monosynaptic excitatory connection with the α-motor neuron supplying the same muscle. 4. The α-motor neuron stimulates the muscle to contract and oppose the stretch. 5. At the same time, inhibitory interneurons inhibit the antagonist muscle (reciprocal inhibition). Example: The knee jerk (patellar reflex) is a classic stretch reflex. Functions: Maintains muscle tone, posture, and stability and helps resist sudden changes in muscle length.