Primary and conjunct motion recordings. Movement plots during primary cervical rotation in the horizontal plane (upper panels) with the associated conjunct movements below. Cervical rotation was first carried out to the left then to the right in one sequence with a small pause in between (asterisks). Conjunct motion in side-bending (middle panels) and flexion/extension (lower panels) are shown for a healthy subject (left column) and a WAD patient (right column). The arrow in the left, middle panel illustrates the range of conjunct motion used for analyses. The sum of conjunct motion in the two associated planes was taken to express total conjunct motion for each primary motion. Note the stiffer movement pattern in the WAD patient (lower two panels to the right).