What structure is commonly referred to as the 'funny bone' when struck?

The structure commonly referred to as the 'funny bone' is the ulnar nerve. When the ulnar nerve, which runs along the inner part of the elbow, is hit or struck, it causes a distinctive tingling or shock-like sensation in the forearm and fingers. This sensation is often described as funny because of its unexpected and unusual nature, despite being uncomfortable.

The ulnar nerve is particularly vulnerable at the elbow, where it runs close to the surface of the skin in a groove called the ulnar groove. This anatomical location makes it easy to strike against hard surfaces, leading to the characteristic sensation that many people experience when they bump their elbow. Understanding the anatomy of the ulnar nerve and its role in sensory and motor functions can help one appreciate why striking this area produces such a notable reaction.