Cubital tunnel syndrome happens when the ulnar nerve, which passes through the cubital tunnel (a tunnel of muscle, ligament, and bone) on the inside of the elbow, is injured and becomes inflamed, swollen, and irritated.

Cubital tunnel syndrome causes pain that feels a lot like the pain you feel when you hit the "funny bone" in your elbow. The "funny bone" in the elbow is actually the ulnar nerve, a nerve that crosses the elbow. The ulnar nerve begins in the side of your neck and ends in your fingers.