I'm trying to create a new race of humanoids that are in appearance almost identical to humans with one exception: They have an extension of their spine protruding from their back, much like a tail. It would however be very long and be used similarly to a scorpion's tail, minus the poison. The way I envisioned it is: it would appear as if it's only bone, similiar in appearance to a human spine, but longer and meant as a weapon, tool for movement (like a spring for long distance jumps) etc.
My concern for this idea is the following: Would the humanoid have any control over the 'limb', considering there is no muscle around the bone? Do I specifically need muscles to be able to control it or is there another solution?
if there are any additional details necessary, I'd be glad to provide.