title: Segmental percentage contributions of cervical spine during different motion ranges of flexion and extension.
abstract: METHODS
  A blind, repeated-measure design was employed in the study.
  
  
  OBJECTIVE
  To quantitatively measure the percentage contribution of segmental angular motion during different motion ranges of cervical flexion-extension for clinical applications and better understanding of cervical biomechanics.
  
  
  BACKGROUND
  Restriction of cervical motion is a major symptom in patients suffering from neck injuries or pathologies. Although segmental angular motion alternation is a criterion for the detection of neck related impairments, the percentage contribution throughout cervical movements is not well understood.
  
  
  METHODS
  A total of 384 image sequences during cervical flexion-extension obtained from 48 healthy adult subjects were analyzed with a precise image protocol using dynamic videofluoroscopic techniques.
  
  
  RESULTS
  The middle cervical spines demonstrated significantly greater angular percentage contributions at C3/4 (29.89%) and C4/5 (37.14%) angles during the initial 1/3 flexion movement; whereas the lower cervical spines revealed statistically greater angular contributions (C5/6: 22.57% to 29.45%; C6/7: 28.80% to 37.42%) from the middle to final 1/3 ranges of flexion movement (P<0.001). With regard to cervical extension motion, the majority of segmental percentage contributions statistically shifted initially from C5/6 level (30.21%) to C4/5 (24.96%) and C5/6 (26.12%) levels, and finally to the C3/4 (27.55%) and C4/5 (29.77%) segments (P<0.001).
  
  
  CONCLUSIONS
  The segmental percentage contributions in this study might imply that the cervical flexion movement initially relied more on the middle cervical segments and later on the lower ones, whereas a motion pattern trend from lower to middle segments was observed during cervical extension.
authors.affiliation: Department of Physical Therapy, HungKuang University, Taichung, Taiwan.
authors.forename: Shyi-Kuen
authors.initials: SK
authors.lastname: Wu
authors.forename: Li-Chieh
authors.initials: LC
authors.lastname: Kuo
authors.forename: Haw-Chang H
authors.initials: HC
authors.lastname: Lan
authors.forename: Sen-Wei
authors.initials: SW
authors.lastname: Tsai
authors.forename: Fong-Chin
authors.initials: FC
authors.lastname: Su
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena / Q000502:physiology; D002574:Cervical Vertebrae / Q000502:physiology*; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*