The forearm joint is unique among motion mechanics: it’s the one that spins.

The forearm’s axis of motion runs parallel to the forearm itself, creating a rotational motion which is used as a primary motivator in techniques like Eddie Van Halen’s famous tremolo motion.

But the ingenious design of the forearm joint allows it to play an arguably even more important role in assisting many other picking motions, either by moving the pick directly, or by changing the orientation of the joints that are doing the movement. In this critical role as a helper motion, the forearm joint lets the player create sophisticated motions which wouldn’t be possible with any single joint alone.