What causes skeletal muscle relaxation? A) nhibitory interneuron releases GABA onto muscle B) Descending neurons from brain directly inhibit muscle fibers C) Motor neuron does not fire action potentials E) Inhibitory motor neuron releases acetylcholine onto muscle

The correct option is C. Motor neuron does not fire action potentials

Explanation:

During contraction, the motor nerve passes down an action potential. A neuromuscular junction is formed by the motor neuron which stimulates the entry of calcium ions. The calcium ions bind to structures called as troponin which stimulates the binding of the filaments, actin and myosin. The filaments begin to contract by using ATP.

During relaxation, the action potential is stopped. Calcium is taken back into the sarcoplasmic reticulum. As a result, actin and myosin filaments do not link and hence, the contraction is stopped.