We started creating little 'cheat sheets' for ourselves to help us remember some of the rotation limits and joint relationships in the human body and thought it might be a good thing to share some of them.
Clavicle animation can be a tough thing to figure out. It's difficult to look at animation reference and see how much movement is coming from the shoulder joint and how much is coming from the clavicle. And when you are responsible to manipulate the rig to create convincing movement and poses, it's good to have an understanding of what is most likely happening with the clavicle based on the rotation of the shoulder joint.
*Shoulder rotates between 0-60 degrees: no rotation in the clavicle
*Shoulder rotates between 60-120 degrees: the clavicle must also contribute rotation to the pose.
*Shoulder rotates between 12-180 degrees: the clavicle continues to contribute rotation and the upper torso also rotates slightly to increase the range.