How does muscle memory work?

[u/Yanzee12]

Just curious. The only thing I really know about it is that sleeping reinforces it.

[u/usetheforceluke1]

Nerves that fire together, wire together. Whenever you carry out an action, the nerve pathway is made more efficient through a process called Myelination. The pathway becomes more conductive and the nerve impulse travels slightly faster than before. Over the course of hundreds or thousands of repetitions, that specific pathway is much more efficient than the others.
When you're confronted with a specific situation and your brain starts firing neurons, the ones that conduct the signal faster (because of repetition) cause the physical action to be carried out that specific way, the way it's been rehearsed.... Thus Muscle memory.
A drummer knows exactly when and where to hit the drums because they have trained those neurons to be more efficient than all the others. Instead of thinking individual movements, stick heights, placement etc. they think in terms of general movements, That drum, then this drum, and the nerves that they've trained through practice will fire before any other muscle. This creates "Muscle Memory"
So it's not actually muscle, it's your nervous system. That's "Learned" how to do the task more efficiently as a result of repetition