When a Person Is Standing with Their Elbow Bent, and Someone

question 51

Multiple Choice

When a person is standing with their elbow bent, and someone grabs their arm and yanks, the biceps will contract and the triceps relax in order to produce a reflexive pull back against the movement. How is this muscle control achieved?

• A) spinal interneurons release excitatory neurotransmitters on the motor neurons of effector muscles
• B) sensory neurons release excitatory neurotransmitters on the motor neurons of effector muscles
• C) sensory neurons release inhibitory neurotransmitters on the motor neurons of antagonist muscles
• D) All of the choices are correct.

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