title: Three-dimensional quantification of the symmetry of normal facial movement.
abstract: OBJECTIVE
  This study examined the right to left symmetry of the displacement of three-dimensional movement of the human face.
  
  
  METHODS
  Displacement data on 42 subjects was collected and analyzed with the Expert Vision Motion Analysis System. Right and left three-dimensional facial displacements were quantified.
  
  
  RESULTS
  Significantly greater left than right three-dimensional displacement across the whole face was measured. The three-dimensional displacement difference ranged from 0.48 mm to 2.28 mm between the right and left sides of the face. The 2-cm inferior pupil markers during the nose wrinkle expression had significantly greater left than right displacement.
  
  
  CONCLUSIONS
  The ranges of displacement differences, along with the mean three-dimensional displacement measures, must be accounted for in the creation of a baseline of the range of normal facial movement.
authors.affiliation: Private Practice of Physiotherapy, Royal Prince Alfred Hospital, Sydney, Australia. slink@zeta.org.au
authors.forename: Susan E
authors.initials: SE
authors.lastname: Coulson
authors.forename: Glen R
authors.initials: GR
authors.lastname: Croxson
authors.forename: Wendy L
authors.initials: WL
authors.lastname: Gilleard
mesh_terms: D000328:Adult; D005149:Facial Expression; D005152:Facial Muscles / Q000502:physiology*; D005154:Facial Nerve / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D012016:Reference Values