eli5: Why can we bend our index finger’s first joint freely but we can’t bend our other fingers first joint(thumb excluded) without the others slightly retracting?
In: Biology
Your fingers don’t move themselves. They’re like puppets controlled by muscles in your arm. How they can move depends on where the strings (tendons) are attached. If you imagine a puppet hand (minus thumb) controlled by strings, with a glove (the skin) covering the hand and the strings, you’ll get a better sense of the limitations.
The ring finger shares a muscle with the pinky and shares a muscle with the middle finger. You can’t move your ring finger if the middle finger is restrained and when you move your pinky or middle finger the muscle pulls on the ring finger. The middle finger more so than the pinky.
Actually I play guitar so in my left hand (and a little with my right) I can do those things. It’s about practice and muscle memory.
… YOU can’t. I can do this with the first joint of my middle fingers just fine. With some practice and stretching, _probably_ so could you.
–Dave, and this is WITH the neuropathy making it impossible for me to cross my fingers any more without outside help
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