Sustained tension applied to a skeletal muscle activates Golgi tendon organs. The resulting autogenic inhibition reaches the alpha motor neuron of the same muscle through which arrangement?

• A Disynaptic inhibition via an inhibitory interneuron activated by Ib afferents ✓
• B Monosynaptic excitation of the homonymous alpha motor neuron by Ib afferents
• C Direct activation of Renshaw cells by Golgi tendon organ collaterals
• D Excitation of gamma motor neurons, which indirectly suppress the alpha motor neuron

Explanation

The Golgi tendon organ is arranged in series with muscle fibers and responds to tension. Its Ib afferents synapse on inhibitory interneurons in the spinal cord, which inhibit homonymous alpha motor neurons: this disynaptic circuit is the inverse myotatic reflex, protecting muscle and tendon from excessive force. Option B is wrong because Ib connections are polysynaptic, unlike the monosynaptic Ia stretch reflex. Renshaw cells are driven by alpha motor neuron collaterals, not by Ib afferents.

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.