system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 what is happening when you get random muscle twitches?

For example, the muscle running up the outside of my left hand has been twitching causing my left finger to move. What's going on in my body (chemically, etc) that causes this to happen?
gpt
The motor neurons that mediate movement aren't perfect, nor are any neurons. In order for a muscle to contract, the motor neuron that is attached to it must fire numerous action potentials (an electrochemical signal). If a motor neuron "misfires" only once or twice, the result is a twitch instead of a full contraction. It's totally normal.

Edit: this is usually normal. It's not inconceivable for an illness of some sort to manifest as muscle twitches, but it is vastly more common to be a simple errant firing of a motor neuron.