Possible Clues:

• It stretches toward the pinkie
• Bone by a radius
• Longest forearm bone
• Usually, the longer of the two main bones of the forearm
• It plays a role in arm-twisting
• Humerus attachment
• Arm section infiltrating all-powerful nation
• Some fanciful name for part of the arm
• It's about the length of a radius
• Longer forearm bone