English: The action potential first comes from the brain, and through motor neurons it reaches the muscle fiber at the motor end plates. At the axon terminal, the energy from the action potential opens the voltage gated channels, after it is opened, Calcium (Ca2+) enters the axon terminal. In turn, vesicles will carry out the Acetylcholine out of the motor neuron into the synaptic cleft. It will diffuse across the synaptic cleft to bind to the ligand (chemical) gated channel receptors on the sarcolemma. This will cause a high amount of sodium to enter and activate action potential to be sent down the t-tubules and open the Ca2+ channels in the sarcoplasmic reticulum. The Ca2+ released will be used in muscle contraction.