What is your funny bone?

Funnily enough, your funny bone isn’t a bone at all. It’s actually the ulnar nerve, which extends from your spine, passing behind the elbow joint and going all the way down to your pinky and ring fingers. This nerve is responsible for giving sensation to your forearm as well as your fourth and fifth fingers and helps stimulate movement in your hand and wrist.

Why does it hurt when you hit it?

There’s a point where the ulnar nerve curves around the elbow joint and is essentially wedged between bone and skin. Specifically, when the nerve reaches the elbow it goes through the cubital tunnel. This is a tunnel of tissue on the inside of the elbow under a bony portion of the humerus (your upper arm bone) called the medial epicondyle.

At this specific point, the nerve is not protected by any muscle. The sensation you feel when you hit this precise spot is actually the nerve being pinched and compressed. Hitting your funny bone happens when your elbow is bent rather than extended because the former opens up this small and sensitive area. This temporarily stops the nerve’s connection to the brain and results in that familiar feeling of pain and numbness. The pain follows the nerve’s path and shoots down into your arm and fingers. Because the nerve is also responsible for some hand and wrist movements, it can take a few minutes to get these movements back after whacking your funny bone.

Getty Images

And while hitting your funny bone is something you can usually laugh about once the pain subsides, in some instances the pain and discomfort is ongoing. Cubital tunnel syndrome is a condition where the ulnar nerve is stretched or pinched easily and frequently, sometimes for extended periods of time. This condition can develop from regular movements where your elbow is bent, like spending large parts of the day making phone calls and holding your phone to your ear. But it can also be the result of abnormal bone growth in the elbow or from intense physical activity that increases pressure on the nerve (for example, baseball pitchers often have cubital tunnel syndrome).

And while the symptoms can be similar to those of hitting your funny bone — although they persist for longer and occur more frequently — some symptoms are more extreme, such as a decreased gripping-ability and difficulty controlling fingers for precise tasks.

Why is it called the funny bone?

It’s not entirely clear how the funny bone got its name, considering it isn’t a bone at all. But there seems to be two main competing theories. The first, is that it’s based on the “funny feeling” you get when you hit your elbow in that not-so-sweet spot. The second, is that it’s a play on words because the ulnar nerve runs along the upper arm bone called the humerus (sounds like “humorous”) that is between your elbow and shoulder.

Despite the uncertainty around its name, one thing’s for sure: hitting your funny bone is really not so funny.

Read the original article on nationalpost.com.

More about: funnybone