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- See:
     - Flexion and Extension Views:
     - Technique:

   

- Upper Cervical Spine:
    - prevertebral soft tissues
    - occipital-atlanto-axial injury:
           - atlanto-occipital disassociation
                  - C1-C2 interspinous space should not be greater than 10 mm;
           - atlanto-axial impaction (rheumatoid C-spine)
           - atlas (Jefferson frx)
           - axis (odontoid frx / hangman frx)
           - atlantoaxial distance & SAC;
                  - ADI in children (< 10 yrs) < 3.5 mm; (see pediatric C-spine)
                  - ADI in adults < 3 mm;
                        - an anterior shift of C1 on C2 of more than 3-5 mm implies injury to transverse ligament (see atlanto-axial subluxation);
                  - shift > 5 mm implies injury transverse & alar ligaments;
           - SAC:
                  - greater than 18  mm is normal normal;
                  - 15-17 mm - grey zone;
                  - less than 14  mm is consisent w/ cord compression;
    - pseudosubluxation of c spine:

- Sub-Axial Spine - Alignment:
    - posterior cortices: (more important than anterior cortices)
         - anterior or posterior translation of vertebral bodies > 3.5 mm implies instability;
         - w/ less than 25% relative shift of one vertebral body over another consider facet frx;
         - w/ 25% relative shift consider unilateral facet dislocation and w/ 50% shift, consider or bilateral facet dislocation;
    - vertebral body angulation / translation:
         - patterns of instability include:
                - 1.7 mm or greater of disk widening;
                - 3.5 mm of translational displacement;
                - angulation between two adjacent vertebra of 11 deg more than contiguous cervical vertebrae;
                - measurements are made from each inferior endplate;
    - anterior cortices:
         - anterior subluxation
         - minimal compression frx of anterior vertebral bodies;
         - tear drop sign: bone chip off antero-inferior aspect;
                - may indicate displacement of disc or posterior fragment of vertebral body into spinal canal & cord injury;
    - spinolaminar line (dorsum of lateral masses) (see oblique view);
         - facet joint widening;
         - rotation of the facets on lateral view;
         - parallel articular process facets;
    - spinous process angulation:
         - C1-C2 interspinous space should not be greater than 10 mm;
         - widening is present when the distance is more than 1.5 times the inter-spinous distance of adjacent spinal segments;
         - fanning implies middle column disrupton

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Biomechanical analysis of clinical stability in the cervical spine.  

Neurapraxia of the cervical spinal cord with transient quadriplegia.