The ulnar nerve is one of the major nerves in the arm, originating from the brachial plexus. It runs along the inner side of the arm and passes through the elbow, where it is often referred to as the "funny bone." This nerve is responsible for providing sensation to the ring and little fingers and controlling some muscles in the hand. Injury or compression of the ulnar nerve can lead to symptoms such as numbness, tingling, or weakness in the hand. Conditions like cubital tunnel syndrome can occur when the nerve is pressed at the elbow, affecting hand function and grip strength.