A large nerve, called the ulnar nerve, passes through the elbow and is the source of the strange pain a person feels when he hits his elbow, explains Mental Floss. The ulnar nerve is also referred to as the funny bone.
The ulnar nerve is protected by a cushion of fat, bone, muscle and ligaments for most of its length. However, when it passes through the elbow, it does not have this layer of protection. When a person bumps his elbow, the ulnar nerve sends signals through the arm that cause the odd, numb, tingling pain, notes Mental Floss. The strange sensation that results from bumping the nerve may also be the reason it is called the funny bone.