Home / Funny / Viral / How Forearm Bones Actually Twist When You Use Your Arm


The human body is just magical looking at all the things it allows us to get done. While we may know how many bones we have in our body or how the immune system fights disease, it's sometimes difficult to know without seeing physical examples.

A video posted by Reddit user ExpertAccident demonstrates one of these mind-blowing actions. The footage features a medical model and shows how the bones of the forearm move; specifically how the radius rotates above the ulna as we rotate the forearm. 

The video lifts the veil on this seemingly simple and common move — you might have done it a dozen times today — and shows how the complex bone structure works when you simply twist your hand. Simply turning your arm upside down forces your bones to flex, gently and without  discomfort. It does this by keeping the ulna (the straight bone on the pinky side of the forearm)  in one place while the radius (the curved bone on the thumb side) rotates around it.

The video garnered a lot of attention on Reddit due to the versatility of the subject and the stunning image of what's going on in our forearms with even the most gentle movements. "I definitely  did this move with just one hand while holding the phone in the other. About 10 times," said one user, to which someone replied, "For some reason the bones are more comfortable crossed, right?" I can't help but feel it now, and it makes me uncomfortable. Am I not the only one?"

People said they felt their hands trying to feel the switch, or just said it looked painful. However, not everyone can do it, so it's better to appreciate it - no matter how strange it may seem. "So my bones got stuck with the twisting motion," said one user. "I can't turn my wrist at all. For those who are able - appreciate your weird curves and twisted bones!

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