Cx biomechanics

Question 1

Describe the movements and ranges of motion available at the cervical spine.

Answer 1

Flexion:
OA: 5
AA: 5
C2-7: 40
Total: 50

Extension:
OA: 10
AA: 10
C2-7: 70
Total: 90

Lateral Flexion:
OA: 10
AA: x
C2-7: 70 
Total: 80

Rotation:
OA x
AA: 90
C2-7: 90
Total: 180

Question 2

What are the limits to excessive flexion in the cervical spine?

Answer 2

The zygapophyseal facet joints (the most resistance), the IVD, the supraspinous & interspinous ligaments, the nuchal ligament the ligamentum flavum, the nuchal ligament, and the tectorial membrane.

Question 3

What are the limits to excessive extension in the cervical spine?

Answer 3

The anterior longitudinal ligament, the bony contact of the spinous processes, and the anterior musculature.

Question 4

What are the limits to excessive lateral flexion in the cervical spine?

Answer 4

The intertransverse ligaments and the uncinate processes.

Question 5

What are the limits to excessive rotation in the cervical spine?

Answer 5

The annulus fibrosis resists excessive rotation due to the opposing oblique arrangement of fibres in the laminae of the annulus.

Question 6

What are the limits to excessive flexion and extension in the OA and AA region?

Answer 6

Flexion is limited by the nuchal ligament, the tectorial membrane, and the bony contact of the dens and the anterior ring of C1.

Extension is limited by passive tension in the anterior atlantoaxial ligament.

Question 7

Describe the biomechanics of flexion and extension in the cervical vertebrae.

Answer 7

The inferior facets of the upper vertebrae slide anteriorly and superiorly on the superior facets of the lower verebrae in flexion.

In extension, the inferior facets of the upper vertebrae slide posteriorly and inferiorly on the superior facets of the lower vertebrae.

Question 8

Describe the biomechanics of lateral flexion in the cervical vertebrae.

Answer 8

Lateral flexion and rotation are coupled in the cervical spine, with these movements occuring towards the same side.

Lateral flexion involves the inferior facets of the upper vertebrae sliding inferiorly and posteriorly on the superior facets of the lower vertebrae towards the ipsilateral side of flexion.

Question 9

Describe the biomechanics of rotation in the cervical spine.

Answer 9

The inferior facets of the upper vertebrae slide inferiorly and posteriorly on the ipsilateral side.

Question 10

How are the vertebral canal and IVF affected by flexion and extension?

Answer 10

The volume of the vertebral canal and IVF are increased in flexion, and decreased in extension.

This means that spinal cord injury or spinal nerve root injury is more common in hyperextended positions rather than flexed positions.

In conditions where the spinal cord or spinal nerve roots are compressed, flexion can bring temporary relief of symptoms.