The crossword clue “Arm bones” indicates that the answer is a plural noun that refers to the bones in our arms. The solution to the clue “ULNAE” is a specific type of arm bone – the ulna. The ulna is one of the two bones in the forearm that extends from the elbow to the wrist and runs parallel to the radius. It is located on the pinky finger side of the arm and is longer than the radius. Therefore, “ULNAE” is a suitable answer for the crossword clue “Arm bones”.