title: Relationship between alignment of upper and lower cervical spine in asymptomatic individuals.
abstract: OBJECTIVE
  The aim of this study was to establish standard values for the normal alignment of the upper cervical spine and to clarify its relationship with the lower cervical spine in terms of alignment
  
  
  METHODS
  Three hundred thirteen asymptomatic volunteers (155 men and 158 women) participated in this study. Lateral radiographs were obtained with the neck in neutral position, and the angles formed by the occiput (Oc) and the axis, the atlas and the axis, and C-2 to C-7 were measured. The mean Oc-C2 angle was 14.5 +/- 8 degrees in men and 16 +/- 8.5 degrees in women; the mean C1-2 angle was 26.5 +/- 7 degrees and 28.9 +/- 6.7 degrees, respectively; and the mean C2-7 angle was 16.2 +/- 12.9 degrees and 10.5 +/- 10.3 degrees, respectively. Although weak, statistically significant negative correlation was observed between Oc-C2 and C2-7 angles (r = -0.31 in men and -0.37 in women), and between C1-2 and C2-7 angles (r = -0.22 in men and -0.22 in women). The correlation coefficient between the Oc-C2 and C2-7 angles was greater than that between the C1-2 and C2-7angles.
  
  
  CONCLUSIONS
  Such relationships between alignment of the upper and lower cervical spines should be taken into consideration when performing occipitocervical fusion.
authors.affiliation: Department of Orthopaedic Surgery, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Kenya
authors.initials: K
authors.lastname: Nojiri
authors.forename: Morio
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Chiba
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Maruiwa
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishizawa
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Toyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001837:Body Weights and Measures / Q000706:statistics & numerical data*; D002574:Cervical Vertebrae / Q000033:anatomy & histology* / Q000502:physiology*; D002648:Child; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009142:Musculoskeletal Physiological Phenomena; D012016:Reference Values; D012737:Sex Factors