Cervical Spine Structure and Function

The average human head weighs around _ lbs in neutral posture

10-12

Composite cervical motion: Total flex/ext = Total rotation = Total LF =

126 SD 22, 144 SD 23, 87 SD 22

how many A-O joints

2

If you lean 15o forward, the head weight is ~ _ lbs

27

how many A-A joints

3

Most cervical spines show evidence of disc degeneration > age

40

With a 30-degree forward, it's ~ _ lbs

40

cervical lateral flexion one way

42

Greater degenerative evidence > age

50

cervical flexion and extension one way

63

cervical rotation one way

72

AKA the head spinning joint

A-A

rotation (~50% of total cervical rotation, ~45o to each side)

A-A

1 pivot joint (dens of C2 with the anterior arch of C1 )

A-A joints

2 plane synovial lateral joints (biconvex superior and inferior zygapophyseal facets C1 -C2 )

A-A joints

The only convex-concave relationship in the spine where the rule holds true

A-O

nodding (~15o flex/ext) with very small amount of lateral flexion (~3o ) and coupled rotation (no pure rotation)

A-O

~15o flex/ext, no true rotation, negligible side bending of occiput on C1

A-O

Convex occipital condyles on concave superior facets of C1

A-O joints

Primarily in horizontal plane

A-O joints

Synovial joints with intra-articular meniscoids

A-O joints

atlas is the

C1

2 large lateral masses with superior (concave) and inferior (sl convex) facets

C1 (atlas)

Facet on internal surface of anterior arch for the dens of C2

C1 (atlas)

Function is to cradle occiput and transmit force down

C1 (atlas)

Shaped like a ring (no vertebral body or spinous process) but wide transverse process

C1 (atlas)

Transverse foramen for vertebral artery (VA)

C1 (atlas)

innervation of The A-O and A-A by

C1 and C2 ventral rami

Based on your understanding of normal arthrokinematics of the cervical spine, which of the following motion segments is MOST likely responsible for producing the rotation seen in this picture?

C1-2

axis is the

C2

Anterior portion of body extends superiorly (dens)

C2 (axis)

Dens articulates with C1 (alar and transverse ligaments)

C2 (axis)

Function is to transmit load of occiput and C1 to lower cx spine and provide rotation of occiput and C1

C2 (axis)

Superior and inferior zygapophyseal facets Bifid spinous process (SP) Transverse foramen for vertebral artery (VA)

C2 (axis)

Lower cervical (Cx) spine is the

C2/3 to C6/7

Disc degeneration most frequently seen at _ and _ levels

C5-6, C6-7

cervical vertebra prominens

C7

R lateral flexion arthrokinematics

R lateral tilt and glide, R facet downslide, L upslide of facet

Cervical plexus lies under _ muscle at C1-4 emerging from posterior border of SCM

SCM

Based on your understanding of normal structure and function of the cervical spine, excessive laxity in the transverse ligament/cruciform ligament complex would MOST likely be associated with which of the following?

Spinal cord compression

• Synovial joints with fibroadipose meniscoids • Large, lax joint capsules • Facets lie between horizontal/transverse and frontal planes (45 degfrom horizontal plane)

Zygapophyseal (facet) Joints C2/3 to C6/7

Uncovertebral degeneration and ostophytic formation with

aging

A-A limited by opposite _ ligament

alar

Attach skull to C2

alar ligament

Becomes taut in craniovertebral flexion and rotation and side bending (contralateral)

alar ligament

Can become compromised (e.g. trauma, RA, Down syndrome)

alar ligament

Limits upper cx flexion and stabilizes C1 and C2 in rotation

alar ligament

Paired ligaments from posterior dens of C2 to medial side of occipital condyles

alar ligament

stop you from rotating to far

alar ligament

A-O Nod/flexion =

anterior roll and posterior glide

Flexion arthrokinematics

anterior tilt and glide, upslide of inferior facet

No joint

atlanto-axial joint (A-A)

Yes joint

atlanto-occipital joint (A-O)

C1 is the

atlas

C2 is the

axis

innervation C2

back of neck

innervation C1-2

beanie

From C3-4 through C7 -T1 a combination of _ above and below the joint around the articular pillars

cervical dorsal rami

A-A rotation: _ facet glides forward and slightly down

contralateral

biconvex means

convex on convex

A-A _ on _

convex, convex

Lateral flexion and rotation to the same side

coupling pattern C2/3 to C6/7

From C1 or C2 to occiput: Anterior A-O and A-A membranes (extension of ALL) limits

extension

From C1 or C2 to occiput: Posterior A-O and A-A membranes (extension of lig flavum) limits

flexion

From C1 or C2 to occiput: Tectorial membrane (extension of PLL) limits

flexion

ligamentum nuchae function to resist _ and resting flexion moment

flexion

Lower cervical spine (C2/3-C6/7) Most motion: Least motion:

flexion and extension, lateral flexion

Aging affects posture: Normal head posture progresses toward _ position accentuated by changes in thoracic kyphosis which _ with age Ability to _ the head declines with age

forward, increases, retract

Uncinate processes enlarge from age 9-14, provide _ and limit lateral flexion

frontal plane stability

General aging changes to the spine apply (e.g., _ in the density and stability of collagen so connective tissue more vulnerable to breakage , _ elasticity, _ proteoglycans content, disc degeneration etc.)

increase, decreased, decreased

A-A rotation _ facet glides back and slightly down

ipsilateral

rotation arthrokinematics

ipsilateral downslide, contralateral upslide

innervation C3

lateral neck

Attached to skull at external occipital protuberance and foramen magnum to SP of C7

ligamentum nuchae

Site of muscle attachments

ligamentum nuchae

Facets lie between horizontal and frontal planes (45o from horizontal plane)

lower cervical spine

SP are bifid: The length of the SP decreases from C2 to C4 and then increases from C4to C7 Transverse foramen for VA Vertebral foramen is large and triangular for the large spinal cord Groove for spinal nerve

lower cervical spine

From C1 or C2 to occiput each could limit lateral flexion and/or rotation but _ will likely limit this first

muscle tension

Convex occipital condyles to articulate with concave facets of C1

occiput

Craniovertebral (upper cervical spine) includes

occiput, C1 (atlas), C2 (axis)

extension arthrokinematics

posterior tilt and glide, downslide of inferior facet

Contralaterally reduced vertebral artery blood flow and velocity at maximum cervical _

rotation

cervical plexus lies on _ and _

scalenes, levator scapulae

Consider greater and lesser occipital nerve piercing _ and their relationship to suboccipital muscles Sub-occipital nerve and it's relationship to suboccipital muscles

semispinalis capitis

In general, joint surfaces of the occiput, C1 and C2 provide only minimal bony stability which means that ligamentous and muscle support are important for

stabilization

Also has longitudinal bands, sometimes called atlantal cruciform ligament

transverse ligament

Can become compromised with certain diseases (e.g. RA, Down syndrome)

transverse ligament

Limits upper cx flexion and allows C2 to pivot (rotation)

transverse ligament

Stretches across ring of C1

transverse ligament

Very strong (dens usually fractures before it tears)

transverse ligament

critical for upper cx spine stability (holds dens to C1 and prevents anterior translation C1/2)

transverse ligament

Clinical tests of cervical ligamentous integrity

transverse ligament, alar ligament

cervical vertebrae have these processes

uncinate

process that gets bigger as you age

uncinate

Site of degeneration leading to foraminal stenosis

uncinate processes

Uncovertebral joints or "Joints of Luschka"

uncinate processes

At risk of injury during rotational movement of the spine

vertebral artery

Carries oxygenated blood to the cerebellum, brainstem, and occipital lobes

vertebral artery

Contributes ~ 11% of cerebral blood flow

vertebral artery