system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does a person know where their body parts are located, (nose, mouth, etc.) without looking? Such as eating popcorn without taking eyes off movie.
gpt
It's called your proprioception sense, and it's provided primarily by 'stretch' receptors in your muscles that tell your brain how far the muscle is extended.  Your brain then knows where your limbs are, and can use that to build a map of where the rest of you is (like your nose and mouth).