The neurotransmitter that stimulates muscle contraction is acetylcholine.
When a nerve impulse reaches the end of a motor neuron, it triggers the release of acetylcholine into the synaptic cleft, the small gap between the neuron and the muscle fiber. Acetylcholine then binds to receptors on the muscle cell membrane, leading to a series of events that cause the muscle fibers to contract.
This process is essential for both voluntary movements, such as walking and writing, and involuntary actions, like breathing and reflexes. Without acetylcholine, the signals that allow muscles to contract would not occur, demonstrating its crucial role in the functioning of the muscular system.