Physiology The depolarization of the skeletal muscle cell membrane by motor nerves is directly produced by: A Change in end-plate potential level to a threshold value B Release of substance P from the motor neuron terminal C Increased concentration of neuromuscular cholinesterase D Activation of muscle contractile proteins 💡 Explanation The depolarization of the skeletal muscle cell membrane by motor nerves is directly produced by: ✓ Correct Answer: A. Change in end-plate potential level to a threshold value