[MDDR] Cervical Spine Biomechanics Flashcards
During flexion of the neck, what is happening to the occipital condyles?
They are gliding posteriorly on C1 (atlas)
During retraction of the head and neck, what is happening to the occipital condyles?
They are gliding posteriorly on C1 (atlas)
During extension of the neck, what is happening to the occipital condyles?
They are gliding anteriorly on C1 (atlas)
During protraction of the neck, what is happening to the occipital condyles?
They are gliding anteriorly on C1 (atlas)
What are coupled movements and provide an example
Coupled movements are those movements that occur automatically between two joints during the performance talof a single physiological movement.
Example: Pure side flexion of the head on C1 vertebrae is not possible without inducing some rotation at the C1-C2 joint.
Essentially, side flexion to the right causes rotation of the occiput towards the left. Why?
The right condyle moves into a more anterior position (extension) and the left condyle to a more posterior position (flexion)
Side flexion of the occiput to the right will be coupled with rotation of the ….. ?
C1 - C2 joint to the left (because the occipital condyles are quite close to the lateral masses of this axis)
The mid cervical spine refers to
C2 to C6
The cervico-thoracic junction (CT) refers to
C7-T1
The AA joint is designed to permit rotation. How is this achieved?
Via the anterior arch of the atlas pivoting on the centrally located odontoid process (dens) of the axis
How much % does the AA joint provide in terms of axial rotation of the cervical spine
Roughly 60%
During flexion & extension of the neck, what is happening to C2-C7 vertebrae in terms of gliding?
Each vertebrae tilts and translates forward on the one beneath, therefore gliding ‘up the slope’ during flexion. In extension, the reverse effect is seen and therefore the vertebrae glides ‘down the slope’
At C2-C7 during rotation/side flexion to the right, what is happening bio-mechanically?
The right inferior articular glides backwards and downwards on the superior facet of the vertebrae below. The inferior facets on the opposite side glides forward and upwards.
Thus, there is a gap on the left side
At the lower cervical spine, why does rotation and side flexion occur together (coupled movements)?
Because of the orientation of the facet joints
What is the main movement at the AA joint?
Rotation, with a little bit of flexion and extension
