Final Answer:
The myotatic reflex circuit is a neural pathway responsible for the monosynaptic stretch reflex, involving the activation of muscle spindles and subsequent contraction of the stretched muscle. The activity of flexor motoneurons is suppressed through reciprocal inhibition mediated by inhibitory interneurons in the spinal cord.
Step-by-step explanation:
The myotatic reflex circuit operates through a feedback loop involving muscle spindles, sensory neurons, and motor neurons. When a muscle undergoes a stretch, the muscle spindles, specialized sensory receptors within the muscle, detect the change in length and initiate action potentials in sensory neurons. These sensory neurons synapse directly onto alpha motor neurons, which innervate the same muscle, leading to its contraction. This direct connection constitutes the monosynaptic stretch reflex, providing a rapid response to changes in muscle length.
To ensure coordinated movement and prevent conflicting muscle actions, the myotatic reflex includes inhibitory interneurons. In the context of flexor motoneurons, reciprocal inhibition comes into play. As the sensory neurons activate the alpha motor neurons of the stretched muscle (agonist), inhibitory interneurons simultaneously inhibit the alpha motor neurons of the opposing flexor muscle (antagonist). This suppression of the flexor motoneurons allows for the efficient execution of the intended movement without interference from opposing muscle groups.
In summary, the myotatic reflex circuit not only facilitates the contraction of the stretched muscle but also incorporates mechanisms like reciprocal inhibition to suppress the activity of antagonistic muscles, promoting coordinated and purposeful movement. This neural circuitry ensures that the body responds appropriately to changes in muscle length, maintaining stability and precision in motor control.