Eli5: How does the skin under my fingernails know to “let go” of the nail once it reaches the end of the finger?

Question

I’ve got a hangnail right now…. I can either rip it off now and deal with the pain, or just wait for it to grow out and then it just lets go somehow.

In: 155

Answer 1

So your nail doesn’t actually grow parallel to your finger, like you might think. It actually grows upward and outward, perpendicular to your finger, from what’s called the ‘nail bed’. Your nail bed cells know to produce the harder cellular structure of a fingernail and they continuously produce more of it, which causes your nail to grow parallel away from your finger.

The nail bed is the part that ‘sticks’ the nail to your finger, as you put it. Where the nail bed ends is where the nail stops sticking.