Neuromuscular junctionMotor end plate

The neuromuscular junction is the specialised synapse between a motor neuron's terminal and a muscle fibre. An arriving nerve impulse releases acetylcholine into the gap; receptors on the muscle membrane respond, an electrical signal spreads through the fibre, and contraction follows.

It matters because it is the last link in the chain from intention to movement, and it degrades with age — junctions fragment and some are lost, contributing to the muscle and power loss of sarcopenia. It is also the target of several drugs and toxins, from botulinum toxin to the agents used in anaesthesia.

In practice, resistance training helps maintain these junctions into later life, which is one of the less-discussed reasons strength training matters for healthy ageing.