Character Rigging - Game Character Development with Maya - page 770

FIGURE 12.56 Position all three control icons for the spine joints.
In the current arrangement, if we rotate one of the lower arrows, the pivots for the
others become misaligned—when we animate them, they won't be moving around
the correct pivots ( Figure 12.57 , left). We want them to stay locked to the joints
they are controlling. We could use a point constraint to make this happen, but the
spine will still animate unrealistically. Instead, we take a simpler approach.