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Chapter 22

Chapter 22. Craniovertebral Junction. Overview. The craniovertebral (CV) junction is a collective term that refers to the occiput, atlas, axis, and supporting ligaments Accounts for approximately 25% of the vertical height of the entire cervical spine. Anatomy. Foramen magnum

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Chapter 22

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  1. Chapter 22 Craniovertebral Junction

  2. Overview • The craniovertebral (CV) junction is a collective term that refers to the occiput, atlas, axis, and supporting ligaments • Accounts for approximately 25% of the vertical height of the entire cervical spine

  3. Anatomy • Foramen magnum • The smaller anterior region of the foramen magnum is characterized by a pair of tubercles to which the alar ligaments attach. • The posterior portion of the foramen magnum houses the brainstem-spinal cord junction. • The demarcation of these two regions is marked by a pair of tubercles to which the transverse ligament of the atlas attaches.

  4. Anatomy • The occipito-atlantal (O-A) joint is formed between the occipital condyles, and the superior articular facets of the atlas (C 1)

  5. Anatomy • The Atlas • The atlas (C 1) is a ring-like structure that is formed by two lateral masses, which are interconnected by anterior and posterior arches • Since this vertebra does not have a spinous process, there is no bone posteriorly between the occipital bone and the spinous process of C 2

  6. Anatomy • The superior-lateral aspect of each of the posterior arches has a transverse foramen to accommodate the vertebral artery

  7. Anatomy • Axis (C 2) • The axis serves as a transitional vertebra between the cervical spine proper and the craniovertebral region • A unique feature of the axis, the odontoid process, or dens is located on its superior aspect • The dens extends superiorly from the body to just above the C 1 vertebra, before tapering to a blunt point

  8. Anatomy • The dens functions as a pivot for the upper cervical joints, and as the center of rotation for the A-A joint. • The anterior aspect of the dens has a hyaline cartilage covered mid-line facet for articulation with the anterior tubercle of the atlas (the median A-A joint). • The posterior aspect of the dens is usually marked with a groove where the transverse ligament passes.

  9. Anatomy • The atlanto-axial (A-A) joint is a relatively complex articulation: • Two lateral zygapophysial joints between the articular surfaces of the inferior articular processes of the atlas, and the superior processes of the axis • Two medial joints: one between the anterior surface of the dens of the axis, and the anterior surface of the atlas, and the other between the posterior surface of the dens and the anterior hyalinated surface of the transverse ligament

  10. Anatomy • Supporting structures • In the absence of an intervertebral disk (IVD) in this region, the supporting soft tissues of the joints of the upper cervical spine must be lax to permit motion, while simultaneously being able to withstand great mechanical stresses

  11. Anatomy • Ligaments • Nuchal • Transverse • Alar and accessory alar • Apical • Vertical and transverse bands of the cruciform • Capsule and accessory capsular ligaments

  12. Anatomy • Nuchal ligament • A bilaminar fibroelastic and intermuscular septum that spans the entire cervical spine • Extends from the external occipital protuberance, to the spinous process of the seventh cervical vertebra • When the O-A joint is flexed, the superficial fibers tighten and pull on the deep laminae, which in turn, pull the vertebrae posteriorly, limiting the anterior translation of flexion and, therefore, flexion itself

  13. Anatomy • Transverse ligament • The major responsibility of the transverse portion of the cruciform ligament is to counteract anterior translation of the atlas relative to the axis, thereby maintaining the position of the dens relative to the anterior arch of the atlas • The transverse ligament also limits the amount of flexion between the atlas and axis

  14. Anatomy • Alar ligaments • The alar ligaments connect the superior part of the dens to fossae on the medial aspect of the occipital condyles, although they can also attach to the lateral masses of the atlas • Function to resist flexion, contralateral side bending and rotation of the neck

  15. Anatomy • Vertebral artery • Supplies the most superior segments of the cervical spinal cord

  16. Anatomy • Muscles • Deep • Posterior suboccipitals

  17. Biomechanics • O-A Joint • The primary motion that occurs at this joint is flexion and extension, although side bending and rotation also occur

  18. Biomechanics • A-A Joint • The major motion that occurs at all three of the A-A articulations is axial rotation, totaling approximately 40° to 47° to each side • Flexion and extension movements also occur: amount to a combined range of 10-15º (10º of flexion, and 5º of extension)

  19. Biomechanics • The direction of the conjunct motion appears to be dependent on the initiating movement • If the initiating movement is side bending (latexion), the conjunct rotation of the joint is to the opposite side • If the initiating movement is rotation (rotexion), the conjunct motion (side bending) is to the same side.

  20. Side bending of the head to the right produces: • Left rotation of the O-A joint, accompanied by a translation of the occiput to the left • Left rotation of the A-A joint • Right rotation of C 2-3

  21. During rotation of the head to the right (rotexion): • Right side bending and right rotation occur at the A-A joint and at C 2-3 • Left side bending and right rotation occur at the O-A joint, accompanied by a translation to the right

  22. Biomechanics • The biomechanics of this region are exploited using the differentiation test to help determine the segment involved

  23. Examination • History • Headaches • Jaw, facial or eye pain (see Systems review) • Ear pain or middle ear symptoms (tinnitus) • Dizziness • Paresthesia of the tongue, face or head • Tongue sensitivity changes (e.g., acidic, metallic tastes)

  24. Examination • Systems review • The craniovertebral region houses many vital structures: • The spinal cord • The vertebral artery • The brain stem

  25. Examination • Systems review • Periodic loss of consciousness • Dysphasia • Diplopia • Hemianopia • Ataxia • Hyperreflexia • Babinski response

  26. Examination • Systems Review • Positive Hoffman or Oppenheim test • Flexor withdrawal • Nystagmus • Quadrilateral paresthesia • Bilateral upper limb paresthesia • Peri-oral anesthesia • Drop attacks • Wallenberg syndrome

  27. Examination • Tests and measures • AROM • Passive overpressure • Isometric resistance

  28. If the patient is able to flex their neck, a C-V fracture or a transverse ligament compromise can be provisionally ruled out

  29. Much more a function of the lower cervical spine, side bending is nonetheless significantly decreased in cases of craniovertebral instability or articular fixation

  30. Rotation • Neck rotation is considered as the functional motion of the craniovertebral joints • If symptoms are not reproduced with neck rotation, it is doubtful whether a craniovertebral dysfunction is present

  31. Loss of Rotation • Serious causes: • Fracture (Dens, Hangman’s) • Muscle splinting • Rotation is the most likely (single) motion to bring on VA signs or symptoms

  32. Loss of rotation • Biomechanical causes • A loss of rotation associated with pain and a history of recent trauma could indicate an acute/sub-acute, post-traumatic arthritis • A loss of rotation associated without pain and a history of chronic trauma could indicate a chronic, post-traumatic arthritis

  33. Loss of rotation • To differentiate the potential biomechanical causes for the loss of rotation, the following tests are used: • Combined motion testing (No H and I or Figure of 8 in this region) • Relevant passive glide delivered at the end of range for end-feel or pain reproduction • Linear/planar segmental stress tests

  34. Combined motions • Flexion and extension at the O-A joints involves anterior-posterior gliding of the occipital condyles • The same gliding (although reciprocal in opposing facets) is utilized in rotation

  35. Therefore, if a symptom or range of motion is drastically altered by adding craniovertebral flexion or extension an assumption could be made that the dysfunction is at the O-A joint not the A-A joint

  36. Similarly, if a symptom or range of motion is not drastically altered by adding craniovertebral flexion or extension an assumption could be made that the dysfunction is at the A-A joint not the O-A joint

  37. Example • The RIGHT O-A joint cannot flex (i.e., the right occipital condyle cannot glide posteriorly): • The predominant functional loss will be decreased RIGHT rotation • The restriction of RIGHT rotation will increase with C-V flexion • However, The restriction of RIGHT rotation will decrease (be less obvious) with C-V extension

  38. Example • The RIGHT O-A joint cannot extend (i.e., the right occipital condyle cannot glide anteriorly): • The predominant functional loss will be decreased LEFT rotation • The restriction of LEFT rotation will increase with C-V extension • However, The restriction of LEFT rotation will decrease (be less obvious) with C-V flexion

  39. Relevant passive joint glide • Example: • If it was determined in the combined motion testing that the RIGHT O-A joint is more restricted or painful with flexion • The joint is taken to the limit of its range of motion i.e., right rotation in flexion (the two motions associated with a posterior glide of the right O-A joint) and the end feel is assessed

  40. Relevant passive joint glide • Example: • If it was determined in the combined motion testing that the RIGHT O-A joint is more restricted or painful with extension • The joint is taken to the limit of its range of motion i.e., left rotation in extension (the two motions associated with an anterior glide of the right O-A joint) and the end feel is assessed

  41. End feel • End feel assessment: • Firm end feel, with or without pain may require mobilization/muscle energy depending on findings at contralateral joint • Loose end feel, with pain is more suggestive of a hypermobility/instability – need to perform stability tests

  42. Examination • The craniovertebral region demonstrates a high degree of mobility, but little stability • Some stability is provided by the ligaments, although they afford little protection during a high velocity injury

  43. Examination • Segmental stability tests. The C-V junction is stressed in the following directions: • Longitudinal (traction) • Anterior (transverse ligament) • Coronal (alar) • Transverse (articular)

  44. Examination • Neurological tests • Cervical myelopathy, involving an injury to the spinal cord itself is associated with multi-segmental paresthesias, upper motor neuron (UMN) signs and symptoms such as spasticity, hyperreflexia, visual and balance disturbances, ataxia, and sudden changes in bowel and bladder function

  45. Examination • Special tests • Vertebral artery tests • Vestibular tests • Sharp-Purser test

  46. Examination • Other tests that can be used: • Palpation • Positional tests • Uni-planar passive physiological mobility tests

  47. Examination • Palpation • Asymmetrical joint geometry is common in this region • Examination of the skin overlying the spine has been found to be very helpful as certain skin changes in a particular location may point in the direction of a dysfunctional spinal area • Palpation can be performed at any time during the examination or as a separate entity

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