Intracellular Recording from a Muscle Fiber

• The muscle fiber is stimulated by a motor neuron (Left).
• Arrival of a nerve impulse at the axon terminal of the motor neuron
  • causes acetylcholine to be released into the neuromuscular junction which
  • creates an end plate potential (EPP) in the membrane beneath it (A)
  • but not farther away (B).
• When the EPP reaches the threshold of the fiber (about −50 mv), an action potential is generated that sweeps along the fiber (A to B in the graph)