How does the nerve supply to a skeleton muscle fibre causes it to contract?
Once the nerve impulse or action potential reaches the end of the nerve it will cause the release of a neurotransmitter called acetylcholine. This neurotransmitter crossed the synapse between the muscle and the end of the nerve (nerves never directly touch muscles) and then it causes the muscle to generate its own action potential. This electrical wave over the muscle then causes the sarcoplasmic reticulum in the muscle cell to release calcium. The release of calcium in the muscle cell causes the muscle fibers to change their shape and bind together. ATP is used as the energy source for the actual contraction.
