Quantification of the three-dimensional displacement of normal facial movement

This study was undertaken to quantify 3-dimensional (3-D) facial movement i n normal subjects, and to identify the individual axes in which this moveme nt occurred. Displacement data on 42 subjects were collected and analyzed w ith the Expert Vision Motion Analysis System. The 3-D displacement was calc ulated by vectorially subtracting maximum marker movement from previously i dentified reference marker points. The 3-D range of normal facial movement was quantified, with the greatest displacement occurring during maximum smi le. When the individual axes were examined, we found that most movement occ urred in the vertical axes for the majority of expressions, followed by the anterior-posterior axis. These results may create an objective baseline fr om which disorders of the facial nerve, and hence, medical, surgical, and p hysiotherapy treatment interventions, can be analyzed in the future.