ABSTRACT
When a motor neuron is activated, an action potential is propagated down the nerve axon and terminates on the neuromuscular junction (NMJ). e NMJ is a space where the action potential cannot cross from the nerve axon to the muscle bers it innervates. us, a chemical messenger is used to transmit the signal from the nerve axon to the muscle bers. As the signal is transmitted down the nerve axon, voltage-gated channels open to release calcium into the terminal button of the NMJ. is facilitates the release of the chemical messenger acetylcholine (ACH) that crosses the space to the motor end plate. is causes an ionic shi– which results in the propagation of the action potential down the basement membrane of the muscle ber and then down the transverse tubule (T-tubules) of the muscle cell (Figure 2.6).
