How does motor memory work?

I just picked up my guitar and decided to play a tune that I haven’t played for about 5 years (Scarborough Fair - the Simon & Garfunkel arrangement). I could only vaguely remember some of the fingering and picking, and was getting a bit frustrated. So then I started reading the SDMB, but still picking the guitar at the same time.

Bada bing! I suddenly realised I was playing it perfectly.

When I didn’t think about it, some part of my brain had accessed the memory and bypassed my conscious mind. What on earth is the mechanism behind that? I vaguely recall that it’s something to do with the hippocampus? Or do I mean hypothalamus?

My mom, the nurse practioner (can diagnose and prescribe, with a masters), says that it totally depends on what part of the body you’re using. Guitar fingering would be remembered by a different part of the brain than if you were remembering dance steps.

I thought it was the cerebellum, but she says that’s only for automatci functions like breathing and beating the heart.

I don’t know (so why am I replying? I am just a nosey parker)
S’like riding a bike. Try this one day - try to concentrate on walking. If you manage to force the task to be conscious it will get quite difficult and you will look like an idiot.

Oh, and I learned a few lame tunes on an electric keyboard that I got for my (12th?) birthday. Years later, with a bit of initial experimentation I was able to play them all perfectly.