title: Morphological changes of the in vitro cervical vertebral canal and its cast form during flexion, extension, and lateral bending.
abstract: OBJECTIVE
  The purpose of this study was to investigate and measure morphological changes in the vertebral canal and its cast form at the level of the cervical spine in vitro during flexion, extension, and lateral bending in cadaver specimens.
  
  
  METHODS
  The morphological changes of vertebral canal and its contents were investigated and measured during experimental flexion, extension, and lateral bending of the cervical spine with 10 fresh specimens (Chinese); the cross-sections and sagittal diameters were also measured by pouring liquid wax into the intervertebral canal.
  
  
  RESULTS
  During lateral bending, the nucleus pulposus was pushed to the opposite side and the inferior cervical nerve roots of the opposite side were stretched. Cross-sectional diameter at the level of C6-7 during flexion was larger than that in lateral bending (P < .05). Comparing extension with flexion, we found that changes in all segments' areas were significant (P < .05). There was no significant difference in the sagittal diameter at any segment during all postures (P > .05).
  
  
  CONCLUSIONS
  During lateral bending, the nucleus pulposus of neck were pushed into the opposite side, and inferior cervical nerve roots of the opposite side were stretched. The C5, C6, and C7 nerve roots appeared to undergo excessive stretch when an excessive lateral bending beyond the physiologic range was undergone. This study provides some additional evidence about the mechanics of cervical spine motion.
authors.affiliation: Department of Orthopedics, Guangzhou Liu Hua Qiao Hospital, Guangzhou, China.
authors.forename: Wu
authors.initials: W
authors.lastname: Li-Ping
authors.forename: Li
authors.initials: L
authors.lastname: Yi-Kai
authors.forename: Liang
authors.initials: L
authors.lastname: Bo-Jin
authors.forename: Manas
authors.initials: M
authors.lastname: Das
authors.forename: Fan
authors.initials: F
authors.lastname: Ji-Hong
mesh_terms: D019412:Anatomy, Cross-Sectional; D002102:Cadaver; D002574:Cervical Vertebrae / Q000033:anatomy & histology* / Q000294:innervation; D004388:Dura Mater / Q000033:anatomy & histology; D006801:Humans; D066298:In Vitro Techniques; D017843:Ligamentum Flavum / Q000033:anatomy & histology; D008297:Male; D008953:Models, Anatomic; D010232:Paraffin; D011187:Posture; D013115:Spinal Canal / Q000033:anatomy & histology*; D013116:Spinal Cord / Q000033:anatomy & histology; D013126:Spinal Nerve Roots / Q000033:anatomy & histology; D013314:Stress, Mechanical
chemical_list: D010232:Paraffin