A: The funny bone isn’t really a bone at all. It’s actually a cluster of nerves called the ulnar nerve. The ulnar nerve is wedged between the bone and the skin near the elbow joint, with little to no cushion or protection. When your elbow is extended, this area is protected, but, if the elbow is bent, it opens up this sensitive area. When you hit that groove, you’re actually pinching the nerve, which is why you experience moderate discomfort and a tingling feeling down the arm.
Source: Cody Bruce, MSN, RN, assistant professor with the Texas A&M Health Science Center College of Nursing, 2016