FlipFact of the Day: Amazingly agile, incredibly sensitive, and impressively versatile, our fingers play a key role in virtually everything we do with our hands, from opening doors to picking up potato chips to typing daily trivia articles. It’s almost like there’s an intricate system of muscles in each finger, controlling every thumbs-up or pointing gesture we make. It might surprise you, then, that there aren’t any muscles in our fingers that make them move—and that the muscles that are in them have absolutely nothing to do with their dexterity.
When we move our fingers, the muscles in our palms and forearms are actually the ones doing the work. They connect to our digits via strong, connective tissue fibers (tendons) that run through our wrists. The ones that straighten our fingers (extensor tendons) are located at the top of our hands. Meanwhile, the ones on the palm side (flexor tendons) allow us to bend them.
That’s not to say, though, that muscles are completely absent in your digits. They do have tiny muscles called arrector pili, which make hairs stand on end whenever they contract (a phenomenon we like to call goosebumps).
So, how does this system work? Say for example, you want to make a fist. Your brain sends a signal via the nerves, prompting the muscles in your hand and forearm to contract. This, in turn, causes the flexor tendons to move the bones in your fingers and thumb accordingly, allowing them to curl up into a ball. Try it; you’ll feel the effort your hand and forearm muscles are exerting.
It’s pretty much like a puppeteer tugging at strings to move a puppet. Thus, in a way, your digits literally are “finger puppets.”
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