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Even the slightest bump in a funny bone can lead to pain ripples up and down the arm and a series of lewd insults ripple from the tongue. So why would hitting this small area of the elbow cause so much discomfort?
The answer is very simple: it is a nerve, not a bone, that gets hit.
To understand where this discomfort comes from, let’s review some key points in human anatomy. To start, the funny bone is scientifically known as the ulnar nerve, which is the primary nerve in the arm. It travels from the spine through the neck, before slipping down the upper arm past a groove in the humerus, the bone that runs from the shoulder to the elbow. After the elbow, the nerve passes through the ulna (the bone on the pinky side of the lower arm) and the radius (the bone on the thumb side of the lower arm) to the wrist. The ulnar nerve is responsible for transmitting information from some fingertips to the brain and back again. In particular, it allows a person to register the sensations in their pinky and ring fingers, as well as control some movement in the hand.
For most of the nerve’s journey, it is stored by bone, muscle, and fat. When the nerve is woven past the elbow, it passes through a small channel called the cubital tunnel. As it crosses this space, it passes through a bony hook at the elbow where the radius and ulna meet the humerus.
Related Topics: Why do we bend our arms when we run?
Why is this area so sensitive?
“When a nerve passes through a bony tunnel at your elbow, it is exposed,” said Dr. Dominic King, MD, a sports medicine physician at the Orthopedic and Rheumatology Institute at Cleveland Clinic. “When you hit a nerve on something hard, you compress it between the elbow bone and the hard surface you’re hitting.”
When pushed over the bony edge, the ulnar nerve experiences what is called ulnar nerve entrapment, or the rapid onset of sharp, electric shock-like pain that extends down the arm and into the hand, and peculiar numbness down the limb.
“Nerves are the way we feel about anything in the body,” King told Live Science. “This is a large nerve very close to the skin, and you feel complete neuropathic pain.”
Hitting a funny bone rarely causes any damage. While the pain usually subsides after a few minutes, it is enough to make the person consider wearing an elbow pad at all times.
hit the nerve
So, if it’s a nerve, why is it called a funny bone? The most plausible explanation lies in the anatomy of the arm. Remember: the large bone that extends from the shoulder to the elbow is called the humerus. get it? Humorous. Funny. If it’s a joke, it’s a joke.
The second explanation lacks humor. It is based on the “funny” sensation a person feels when a nerve is impinged, suggesting that it has been described by someone who has a very high pain tolerance.
Other mammals also have a similar composition, but they rarely encounter the same problem. These animals are protected by more muscle mass around the sensitive nerve that builds up around the different ways the animals move. The padding adds a level of protection against this not-so-funny experience.
Originally published on Live Science.
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