The term 'muscle memory' is not a scientific term, and its actually wrong.   But the term does accurately describe how it FEELS when your body does  a movement or skill without any effort from your brain.
 
 Its feels like your muscles remember what to do  all by them selves. Of course, this is not the case.
 
In actuality, the process of motor skill acquisition has been well studied and understood  in many fields from child development to elite sport and expert musicians and many more. 
 
The pursuit to improve the process remains. How can people get better at a skill. How can the movement educators help train  the movers?