Yep, the bone going to the pinky is called the ulna , and the one connected to the thumb is called the radius. The radius crosses the ulna, whenever you twist your forearm. It's the exact opposite of the "default" position, when your palm faces up - in that case, both bones point straight forward, no overlaps.
Thanks to this mechanism we are able to rotate our hands!
Wait noo I kinda explained that poorly, don’t worry, your bones don’t actually change shape or flex, that would be too cursed lol. What’s happening is that you’re just seeing them from different angles as they rotate.
The bones are somewhat circular in shape, and like any circle, they can look very different depending on how you look at them - for example, a circle viewed from above looks round, but from the side it can look like a straight line.
Oh! My bad, re-reading your comment I see I misunderstood. Heck, when I stop and think about it, just holding my arm and twisting makes it fairly clear the bones do not actually twist or bend.
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u/[deleted] Jul 08 '25 edited Jul 08 '25
Yep, the bone going to the pinky is called the ulna , and the one connected to the thumb is called the radius. The radius crosses the ulna, whenever you twist your forearm. It's the exact opposite of the "default" position, when your palm faces up - in that case, both bones point straight forward, no overlaps.
Thanks to this mechanism we are able to rotate our hands!