Help with Mechanim IK Range of Motion Restrictions

Hello,

I'm using Mechanim's built in Inverse Kinematics functions to make my own run-time posable human models (think ergonomic manikin), however I have noticed that restrictions in Range of Motion (aka joint rotation/ muscle setup for avatars) that would normally apply to any animations I might add do not apply to the mechanism IK layer.

Is my best bet to use logic in LateUpdate() to limit the rotations, or am I missing a built in function/method for applying the existing muscle muscle structure to my models?

Thanks in advance,

Madeline