End-plate potential

The End-plate potential is a chemically induced change in electric potential of the motor end plate (the portion of the muscle-cell membrane that lies opposite the terminal of a nerve fibre at the neuromuscular junction). The end-plate membrane is electrically polarized, the inside being negative with respect to the outside because of an uneven distribution of ions.

Acetylcholine released from the terminal of the pre-synaptic membrane, in response to an action potential, triggers a post-synaptic action potential. This in turn causes a twitch in the muscle fibre.