A stray dog bit my second finger.
My callus on the middle finger on my right hand is getting pretty hard.
Don’t stick out your middle finger!
The middle finger is the middle finger, of course! And because we don't see the difference, it's your middle toe too. Stick that up the next time someone makes you mad.
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!