FABS Quiz 12

What region is the most mobile in the spine?

Craniocervical region (neck)

Upper cervical spine consists of what joints?

C0–C1 (atlanto-occipital) and C1–C2 (atlanto-axial)

Lower cervical spine consists of what segments?

C2–C7 facet (apophyseal) joints

What type of joint is C0–C1?

Condyloid (biaxial diarthrotic)

What type of joint is C1–C2?

Pivot joint (trochoidal)

What is special about lower cervical facet orientation?

~45° angle allowing motion in all planes

Primary motion of C0–C1

Flexion/extension (“nodding”)

Flexion ROM at C0–C1

~5°

Extension ROM at C0–C1

~10°

Arthrokinematics of flexion at C0–C1

Convex occipital condyles roll anterior, slide posterior

Arthrokinematics of extension at C0–C1

Roll posterior, slide anterior

Lateral flexion at C0–C1 is coupled with what?

Contralateral rotation

Rotation at C0–C1

Minimal

Primary motion of C1–C2

Rotation

% of cervical rotation at C1–C2

~50%

Rotation ROM at C1–C2

35–40° each side

Flexion at C1–C2

~5°

Extension at C1–C2

~10°

What structure acts as pivot for C1–C2 rotation?

Dens (odontoid process)

What ligament stabilizes dens?

Transverse ligament

What ligaments check rotation at C1–C2?

Alar ligaments

What motion occurs returning to neutral from rotation?

Inferior translation (screw-home mechanism)

Main motions of lower cervical spine

Flexion, extension, rotation, lateral flexion

Flexion, extension, rotation, lateral flexion

35–40°

Extension ROM lower cervical

55–60°

Rotation ROM lower cervical

30–35°

Lateral flexion ROM lower cervical

30–35°

Flexion facet movement (C2–C7)

Inferior facet slides anterior & superior

Extension facet movement

Inferior facet slides posterior & inferior

Coupled motion in lower cervical rotation

Ipsilateral lateral flexion

Coupled motion in lower cervical lateral flexion

Ipsilateral rotation

Spinous process moves toward what?

Convexity

Protraction motion pattern

Protraction motion pattern

Retraction motion pattern

Lower cervical extension + upper cervical flexion

Which has greater range: protraction or retraction?

Protraction (~80% more)

Ideal neutral head position

~35% forward from full retraction

SCM unilateral action

Ipsilateral lateral flexion + contralateral rotation

SCM bilateral action

Flexes lower cervical, slightly extends upper cervical

SCM contributes to what posture?

Forward head posture

Scalenes unilateral action

Lateral flexion

Scalenes bilateral action

Flex cervical spine + elevate ribs

Clinical issue with scalenes

Can compress brachial plexus

Longus colli function

Cervical flexion + stabilization

Longus capitis function

Flexes upper cervical

Deep neck flexors act like what ligament?

Dynamic ALL

Function of suboccipital muscles

Fine control of C0–C1 and C1–C2

Innervation of suboccipitals

Suboccipital nerve (C1)

Splenius unilateral action

Ipsilateral rotation + lateral flexion

Splenius bilateral action

Extension

Flexion compresses which part of IVD?

Anterior

Flexion causes tension where?

Posterior annulus

Nucleus moves which direction in flexion?

Posterior

Extension compresses which part?

Posterior

Extension causes tension where?

Anterior

Nucleus moves which direction in extension?

Anterior

Lateral flexion compresses which side?

Ipsilateral

Rotation stresses IVD at what angle?

~45°

Flexion effect on IVF

Increases size

Extension effect on IVF

Decreases size

Ipsilateral side bending effect

Ipsilateral side bending effect

Contralateral side bending effect

Increases IVF

Cervical nerve position in IVF

Lower third

Cervical canal size is greatest in what position?

Flexion

Cervical canal size is smallest in what position?

Extension

Patients with stenosis are most vulnerable during?

Hyperextension

Compressive loads increase during what motions?

End-range flexion and extension

Which cervical levels have highest stress/injury risk?

C4–C5, C5–C6