Hi lol I saw your reblog on my post and I also wondered why russian would use the same word for hand and arm so i googled around a bit: I did not really find an explanation other than the hand being a part of the arm; like if you wave your hands, your essentially waving your whole arm. Native speakers also say it doesn't matter in conversational speech. There are anatomical terms for hand, upper and under arm that are used in medical contexts for when the distinction actually matters.
I also came across other languages, like Japanese for example, that don't distinguish between foot and leg because the foot is part of the leg! :D
hi omg thank you for looking that up!! yeah that made me go 🧐🧐 because i thought there might be problems e.g. at the doctor but i guess that's where the medical terms are used
god i love languages, спасибо for telling me <33
