Question

During a stretch reflex, the extrafusal motor neuron is excited directly by the a. intrafusal motor neuron. b. muscle spindle receptor. c. spindle afferent neuron. d. intrafusal muscle. e. muscle.

Answer 1

b. muscle spindle receptor.

Explanation: During a stretch reflex, the extrafusal motor neuron is excited directly by the muscle spindle receptor. Muscle spindles are sensory receptors located within the muscle fibers that detect changes in muscle length and provide this information to the central nervous system. When a muscle is stretched, the muscle spindle receptors are activated, leading to a reflexive contraction of the muscle to prevent overstretching.