A neuromuscular junction is a synapse between a motor neuron and skeletal muscle where they meet. At this junction, the motor neuron releases acetylcholine stored in vesicles into the synaptic cleft, which then binds to nicotinic acetylcholine receptors on the skeletal muscle cell membrane, causing the muscle cell to depolarize and contract. The motor neuron is the presynaptic cell that releases neurotransmitters, while the skeletal muscle cell is the postsynaptic cell that receives them and contracts in response.