We all know the feeling: you’re swanning about, not a care in the world, when you carelessly smack your elbow against a door handle or countertop, that almost insignificant-seeming bump sending a disproportionately painful twinge and tingling sensation down your arm. That’s right, we’re talking about the funny bone. While you’re almost certainly familiar with the sharp pain that comes from hitting it, you may not be quite so clued up about what’s actually going on when you do.

Thankfully, we’re here to help, asking, and answering, the question: what happens when you hit your funny bone?

First up, the funny bone isn’t a bone at all. It’s actually a nerve, called the ulnar nerve, which runs along the arm and passes behind the elbow. It extends from the neck to the fingers, all the while relaying information to and from the brain. Specifically, it allows us to register sensations in our ring and pinky fingers and helps us to move these digits, as well as our forearms and hands.

For the most part, this bundle of nerves is protected by layers of bone, muscle, and fat, but as it works its way past the elbow, it is briefly exposed. It travels behind the medial epicondyle – the bony bump inside the elbow – along a short channel called the cubital tunnel. 

Here, it is sandwiched between bone and skin, unprotected and practically daring you to catch it on a sharp edge. If, or should we say when, you do, even a small knock can result in an inordinate amount of pain, as the vulnerable ulnar nerve gets temporarily squashed between the offending object and bone in the elbow. The sensation shoots down the arm, leaving us with that strange, electric shock-like numbness.

It’s similar to what happens when our limbs “fall asleep”: nerves become pinched and we experience that familiar fuzzy feeling of pins and needles.

Generally, when you hit your funny bone, the feeling is fleeting, disappearing within a few minutes. However, prolonged or persistent pain can occur with cubital tunnel syndrome, which occurs when the cubital tunnel becomes inflamed, swollen, or irritated, often because of injury. 

A one-off whack to the elbow might not be too funny, but remember it could be worse.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current. 

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.