Manny Twist Bones, How?

i’m trying to work out how the twist bones on manny are being driven by the hand etc?
I’ve looked in the ABP_Manny_postprocess and can see how the pose drivers are driving correctives but when looking through the anims and poses theres nothing thats making the arm twist, just animating the hand up and down like a flap.

can anyone help?

thanks!

i’ve since found all of this in the ‘control rig’ before the pose drivers, I mistakenly thought control rig was referring to my control rig for direct animation.