I have been reading a little in Norkin & Levangie "Joint Structure and Function" 4th ed  in the spine chapter. If you have the book, my question comes from pg 146. The author is talking about disk/vertebral body height ratios. They say the ratios are greatest in the C & L spine and smallest in the Tspine. The greater the ratio the greater the mobility [as this] reflects the greater functional needs for mobility found in the cervical and lumbar region.  In your opinion does this contradict Gray Cook's joint by joint approach. In the movement book he discusses the greater need for mobility in the hips and Tspine and stability in the lumbar spine. What are your thoughts?