Eli5: How can we move almost any muscle the time we want? How does the brain knows it’s that specific muscle that you want to move?

Question

Like, I can be there just sitting and think. “Now I’m gonna move my middle finger”, and just do it, no reason at all. How does the brain know what muscle is each, how does a signal is determined to make you move the finger you want? Does the brain have a “map” or something of every muscle in your body?

In: Biology

Answer 1

As a fetus your DNA wires up your muscles to a bunch of unlabeled ‘buttons’ in your brain. Slightly later in development your brain is bored and starts mashing buttons to see what happens, and starts labeling the buttons. Some people never find the ‘wiggle your ears’ button, for example. As a baby your brain develops enough to start arranging button presses into goals — crawl over there, grab that dangerous item someone left in your reach, put it in your mouth.