That’s not very funny!

Today’s topic is one that, if you have an elbow, I’m sure you are familiar with. I’m confident that, at some point, you’ve managed to whack your elbow in such a way that pins and needles shot through your arm, funny tingling went through your hands, or just downright pain reverberated through your elbow. I’ve done it more times than I can count. And, of course, whenever I do, I know exactly what to blame.

My funny bone.

But hitting your funny bone isn’t really very funny, is it? In fact, it hurts! I want to know – what is the funny bone? Is it really a bone? Why do we have one? And why is it called the funny bone, anyways? Shouldn’t it be called the hurts-a-lot bone?

Actually, the funny bone is not really a bone. It’s a nerve – specifically, the ulnar nerve, which connects your fourth and fifth fingers to your nervous system and helps control the movement of your hands. The ulnar nerve goes from your hand to your shoulder, passing around the back of your elbow. There, it sits directly on top of the humerus, the bone of your upper arm. Because of its position on top of the bone, the only protection this nerve has is the skin of your elbow. It has no other fatty cushion to serve as a shield. In fact, the ulnar nerve is the only exposed nerve in the human body. All the rest of your nerves are deeply embedded in deep tissue, ligaments or muscles. But because this nerve has no such protection, it can come into direct contact with your humerus. So when you bang your elbow just wrong, the ulnar nerve bumps into the bone, and it sends pain signals through the nerve. Because this nerve is the main connector for your ring and pinkie fingers, in fact, the most common pain associated with hitting your funny bone is tingling in those fingers. Some lucky people, however, don’t feel any real pain when they hit their funny bones, just a funny tingling feeling. And that’s probably why it’s called the funny bone.

So why do we have this exposed nerve in our bodies? It seems like a strange place to put it, doesn’t it? Unfortunately, there isn’t a lot of choice when it comes to the nerves in our elbows. Elbows are, by nature, a lot of bone and not much else. To connect our forearms to our upper arms, the ulnar nerve has to run up the backs of our elbows. This is unlike the joint on our legs that is analogous to our elbows – the knees. Knees have a lot more connective tissue surrounding them than elbows, and thus the nerves are much better protected.

Speaking of comparing knees and funny bones – is the funny bone comparable at all to the reflex kick you have when the doctor taps your knees with that little hammer? Actually, not really. That kick reaction is called the knee jerk, and it is caused by an impact on a tendon. The patellar tendon runs down from your quadriceps muscles (in the front of your thigh), over your kneecap, and down to the lower leg. When the knee is held loosely at a 90 degree angle, with your lower leg hanging freely, and the patellar tendon is tapped, it sends a message to your nervous system that the tendon and the attached muscles have been stretched. The nervous system then sends a rapid message back to the muscle to contract, causing your thigh muscles to tighten. And this tightening makes your lower leg kick out.

So the funny bone and the knee jerk are 2 different physiological reactions. Personally, I much prefer the knee jerk reflex to hitting my funny bone. The knee jerk reaction is interesting. The funny bone reaction – well, I think it’s just painful.