Thumb, Big Toe
noun
Your parent finger is your thumb! It's bigger than your other fingers, so that means it's in charge too! This goes for the fingers on your feet too, I mean, your toes. So the parent toe is your big toe.
おやゆび
This word uses the kun'yomi readings from both kanji, probably because it includes body parts. You know them both already, so now you know this too!
親指を放してくれ！
Let go of my thumb!
うちの家族は全員親指にホクロがあります。
Everyone in my family has a mole on their thumb.
足の親指にイボができました。
I got a wart on my big toe.