# Blender twisting parts of mesh when rigging

I have a problem when I rig a mesh and that is when I put the arms of my mesh up in the air for example some parts of it get twisted.

I've tried looking at the XYZ orientation and the weight painting with no succes.

Here are pictures illustrating the problem. (possibly NSFW, hover to view)

here is the .blend file

female base rigged

• You can upload the file to a service such as pasteall and then share the link here. – iKlsR Feb 8 '14 at 19:59
• ok, thanks I just uploaded the file and edited the post. – Dylan Velez Feb 8 '14 at 20:20
• This happens only with IK controls on this rigify rig, if you imported this from makehuman you could switch to the mhx rigs where everything works as expected. – stacker Feb 8 '14 at 22:43
• I rigged it the normal way by applying an armature modifier and then making the automatic weights(ctrl + p) i didnt doa anything in makehuman, how can i fix that? – Dylan Velez Feb 9 '14 at 1:19

Since you are using two bones for each upperarm for some reason (which is unlike normal human), the constrained bone DEF-upper_arm.01.L doesn't follow the rotation of its control bone or even DEF-upper_arm.02.L, which would lead to the problem. As shown below:
There would be a few ways to fix this, but I'm really not sure why you structed and set the control bone for upper arm like this (I assume you are trying to simulate the natural-looking muscle stretch). However, I think at least an additional Copy Rotation constraint onDEF-upper_arm.01.L is needed here.
• This is a very complicated rigging. If you are the man who created it, then you may exactly know what you are doing. Yep, you can make it one bone, as well as the lower arm, thighs and shins, since that's how human armature looks like. Or, as I said, you may also add Copy Rotation constraint to the DEF-upper_arm.01.L, to let it follow the rotation of control bone. If it has to. – Leon Cheung Feb 9 '14 at 8:55