The term "ulnar" refers to anything related to the ulna, one of the two long bones in the forearm. The ulna runs parallel to the radius and is located on the side opposite the thumb. It plays a crucial role in the structure and function of the arm, particularly in movements involving the elbow and wrist. In anatomy, the ulnar nerve is a significant nerve that runs along the ulna. It is responsible for sensation in parts of the hand and controls some muscles in the forearm. Issues with the ulnar nerve can lead to conditions like cubital tunnel syndrome, which causes pain and numbness in the hand.