Sheet1 Page 1 Review Questions Chapter 13 Answer Key 1. Define, in one sentence, motor unit. How does it differ from motor neuron pool? A motor unit consists of one alpha motor neuron and all the muscle fibers that the alpha motor neuron innervates. This is the elementary component of motor control. A motor neuron pool consists of all the alpha motor neurons that innervate a single muscle. 2. Your doctor taps the tendon beneath your kneecap and your leg extends. What is the neural basis of this reflex? What is it called? When your doctor taps the tendon beneath your kneecap, the tendon attached to the quadriceps muscle of your thigh is stretched. When this muscle is stretched, the musclespindle afferents deliver sensory feedback about the muscle length. This causes the muscle to contract and your leg to extend. This is a monosynaptic reflex arc involving the spindle afferents that enter the dorsal horn and the motor neurons that control the muscle. The kneejerk reflex tests the intactness of the nerves and
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