What nerve is commonly referred to as the "funny bone"?

What nerve is commonly referred to as the “funny bone”? The answer is the ulnar nerve. It passes behind the medial epicondyle of the humerus at the inside of the elbow, where it lies close to the skin with little protection from muscle or bone.

Striking this area can compress or irritate the nerve, producing the familiar electric-shock sensation that travels down the forearm into the hand. The ulnar nerve supplies sensation to the little finger and the adjacent half of the ring finger, as well as parts of the palm and the back of the hand.

It also controls many small muscles involved in precise finger movements, which is why it is sometimes nicknamed the “musician’s nerve.” Repeated pressure or bending at the elbow can cause cubital tunnel syndrome, an ulnar-nerve entrapment that may lead to tingling, numbness, weakness, or reduced grip strength.

The phrase “funny bone” is a wordplay mystery. It may refer to the peculiar sensation produced when the nerve is struck, or it may be a pun on the humerus, the upper-arm bone, whose name sounds like “humorous.” The nerve—not the bone—is responsible for the shock-like feeling.