cervical spine


Cervical Spine Anatomy




Structures Present



  • 7 cervical vertebrae

  • 6 intervertebral discs

  • 8 pairs of exiting nerve roots

  • Cervical lordosis (natural inward curve)




Cervical Lordosis



  • Average curvature from occiput to C7 = 40°

  • Most lordosis occurs at the C1–C2 segment






Cervical Vertebrae




Typical Cervical Vertebrae



Usually C3–C6


Common features:


  • Small vertebral body

  • Large vertebral foramen

  • Transverse foramina

  • Bifid spinous processes (often)






Atypical Cervical Vertebrae




C1 – Atlas



  • First cervical vertebra

  • Supports skull

  • Ring-shaped

  • No vertebral body

  • No spinous process




C2 – Axis



  • Second cervical vertebra

  • Has dens (odontoid process) projecting upward

  • Allows head rotation (“no” movement)




C7 – Vertebra Prominens



  • Seventh cervical vertebra

  • Long prominent spinous process

  • Easily felt at base of neck






Cervical Spine Joints




1. Atlanto-Occipital Joint




Articulating Surfaces



  • Occipital condyles of skull (convex)

  • Superior articular facets of atlas (concave)




Function



Mainly allows:


  • Flexion / extension of head (“yes” movement)

  • Slight lateral flexion






2. Atlantoaxial Joints



There are:


  • 1 Median atlantoaxial joint

  • 2 Lateral atlantoaxial joints






Median Atlantoaxial Joint




Type



  • Synovial pivot joint




Articular Surfaces



  • Convex rectangular facet on front of dens

  • Concave facet on inner aspect of anterior arch of atlas

  • Posterior surface of dens articulates with transverse ligament




Function



  • Rotation of head






Lateral Atlantoaxial Joint




Type



  • Plane synovial joint




Articular Surfaces



  • Two concave facets of atlas

  • Articulate with two convex facets of axis




Function



  • Assists rotation






Cervical Ligaments




Upper Cervical Ligaments



  • Transverse ligament

  • Alar ligaments (x2)

  • Apical ligament

  • Ligamentum nuchae

  • Posterior atlantoaxial ligament

  • Anterior atlantoaxial ligament

  • Anterior atlanto-occipital membrane

  • Posterior atlanto-occipital membrane






Transverse Ligament




Role



  • Holds dens against atlas

  • Prevents anterior displacement of atlas on axis




Divides atlas ring into:



  • Anterior compartment = dens

  • Posterior compartment = spinal cord




Important



Very important for upper cervical stability





Alar Ligaments




Attachments



  • From either side of dens

  • To medial aspects of occiput




Tightness



  • Relaxed in extension

  • Tight in flexion




Functions



  • Prevent distraction of C1 on C2

  • Limit:

    • Flexion

    • Rotation

    • Side flexion







Apical Ligament



  • Runs from apex of dens

  • To anterior margin of foramen magnum






Ligamentum Nuchae



  • Continuation of supraspinous ligament

  • Extends from C7 spinous process to external occipital protuberance

  • Deep part attaches to posterior tubercle of atlas






Lower Cervical Ligaments



  • Anterior longitudinal ligament

  • Posterior longitudinal ligament

  • Ligamentum flavum

  • Intertransverse ligaments

  • Interspinous ligaments

  • Ligamentum nuchae






Cervical Spine Movements




Main Movements



  • Flexion

  • Extension

  • Rotation

  • Lateral flexion

  • Protraction

  • Retraction






1. Cervical Flexion



Approx range:


  • 70°



Observation:


  • Chin should reach sternum

  • Or within two finger widths of sternum






2. Cervical Extension



Approx range:


  • 70°



Observation:


  • Forehead should become parallel to ceiling






3. Cervical Rotation



Approx range:


  • 90°



Observation:


  • Nose should line up with acromion process



Can be measured using goniometer.





4. Cervical Lateral Flexion



Approx range:


  • 45°




Goniometer Position



  • Axis at C7/T1

  • Moving arm aligned with external occipital protuberance






5. Protraction



Forward head movement:


  • Chin moves forward






6. Retraction



Backward head glide:


  • Chin tucks in






Muscles Acting on Cervical Spine




Flexion Muscles



Main muscles:


  • Sternocleidomastoid

  • Scalenes






Extension Muscles



Main muscles:


  • Levator scapulae

  • Upper fibres of trapezius

  • Erector spinae group






Protraction Muscles




Lower Cervical Flexors



  • Sternocleidomastoid

  • Anterior scalene

  • Middle scalene

  • Longus colli




Upper Cervical Extensors



  • Semispinalis capitis

  • Longissimus capitis

  • Splenius capitis

  • Suboccipital muscles






Retraction Muscles




Lower Cervical Extensors



  • Splenius cervicis

  • Semispinalis cervicis

  • Longissimus cervicis




Upper Cervical Flexors



  • Longus capitis

  • Rectus capitis anterior