The Ulnar Nerve
Your 'funny bone' is actually the Ulnar Nerve. This nerve starts at your neck and runs all the way down to your pinky and ring fingers, carrying signals between your brain and your hand.
Most nerves are protected by thick layers of muscle, fat, or bone, but the ulnar nerve is an exception at the elbow.
The Exposed Tunnel
At the back of your elbow, the nerve passes through a narrow space called the Cubital Tunnel. In this specific spot, the nerve is protected by only a thin layer of skin and a tiny bit of fatty tissue.
This makes the nerve extremely vulnerable. When you 'hit your funny bone,' you are actually squishing the nerve directly against the hard humerus bone.
The Electric Jolt
Nerves work using tiny pulses of electricity. When you strike the ulnar nerve, you temporarily 'jumble' its electrical signals. This sends a chaotic burst of information to the brain.
Instead of feeling a normal 'bruise' pain, your brain interprets this chaotic signal as a strange mixture of numbness, tingling, and an electric shock.
The Name Mystery
Why is it called the 'Funny Bone'? Some think it's because the tingling feeling is so strange that it's almost 'funny.' Others believe it's a pun on the bone it sits against: the Humerus.
