Cervical Spine Biomechanics

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Overview

C0-1 C1-2 C2-7
Anatomy 1. Superior facets of C0 (Atlas): 28° in sagittal and transverse planes

2. No disc

1.  C1 has convex facet joint surface (allow C1 facet to slide in AP direction over C2)

2. No disc

3.  Transverse lig : prevent dense posterior dislocation

4.  Alar lig: limiting rotation

Anatomy structure grossly similar.

1. 2x uncovertebral joints (joints of Luschka) at each segments. They are not true synovial joints (clefts at the lateral edges of IVD between uncinated process inferiorly, and the edge of the vertebral body above)

2. 1 disc between each vertebra body.

3. 2 facet joints: at 45° inclination to horizontal plan (pure rotation, side bending is limited)

Biomechanics
  • Flexion/extension (nodding): 15°
  • Side bending: 5°
  • Rotation 5°
Rotation: 45° both directions.

(Rotation in full flexion is C1-2 rotation)

  • Side bending and rotation coupled -> uncovertebral joints at the convexity open out ->displacement of the disc towards the convexity. pure side bending is limited
  • Flexion/extension combined with rotation and translation.
  • Flexion: IVD compressed anteriorly; superior vertebral body slides anteriorly
  • Extension: superior vertebral body slides posteriorly, IVD compressed posteriorly. Anterior fibres of AF are stretched.

Resources

An old four part article series: