The term 'ulnae neighbors' refers to the two bones that are located on either side of the ulna bone in the human arm. These two bones are the humerus (6 letters) and the radius (5 letters). The humerus is the bone that connects the shoulder to the elbow, while the radius is the bone that connects the elbow to the wrist. Together, these two bones form the upper arm and provide stability and support for the arm.