The "funny bone" is not actually a bone, but rather a common term for the ulnar nerve, which runs along the inside of your elbow.
Understanding the Ulnar Nerve
Despite its misleading name, the "funny bone" refers to a nerve bundle, not skeletal structure. When you hit this particular spot, the sensation of tingling, numbness, or even a sharp pain isn't due to striking a bone, but rather from the compression of this sensitive nerve.
What is the Ulnar Nerve?
The ulnar nerve is one of the main nerves in your arm. It plays a crucial role in providing sensation to parts of your hand and controlling various muscles in the forearm and hand.
Here's a quick look at key facts about the ulnar nerve:
| Feature | Description |
|---|---|
| Actual Identity | Ulnar nerve (not a bone) |
| Type | Peripheral nerve |
| Origin | Starts in the spine, extends from the neck |
| Path | Travels through the arm, passing behind the medial epicondyle (the "funny bone" spot) at the elbow, and continues down to the hand |
| Innervation | Primarily provides sensation to the pinky finger and half of the ring finger, and controls certain muscles for grip and fine motor skills |
Where is the Ulnar Nerve Located?
The part of the ulnar nerve commonly referred to as the "funny bone" is located at the elbow. It passes through a narrow groove on the inside of the elbow, just behind the bony prominence known as the medial epicondyle. In this specific location, the nerve is relatively exposed and lacks significant muscular or fatty tissue protection, making it vulnerable to impact.
Why Does Hitting Your "Funny Bone" Hurt?
When the ulnar nerve is struck at the elbow, the sudden impact compresses it against the underlying bone. This compression sends a strong, unusual signal along the nerve pathway, resulting in the characteristic tingling, electric-shock sensation, or sharp pain that extends down into the forearm and often to the pinky and ring fingers. The "funny" part of the name is thought to come from the peculiar sensation, or perhaps from its proximity to the humerus bone (a pun on "humorous").
