I thought you would like to know about this word: "acnestis."
This is the part of your back that you cannot reach when it starts to itch. Not kidding. The word is not in common usage because one is usually too busy swearing to think of it.
"Twist his wrist up into his acnestis..."
"Strike him solidly in the acnestis..."
Karate teachers talk about every other part of the body, so why not this one?
BDC