Biomechanics of the Cervical Spine Flashcards by Courtney Kloes

T/F: there are less muscles in the cervical region than any other?

False (there are more)

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What part of the vertebral column is the most mobile?

Cervical

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What is the cervical spine’s “job”?

maintain head posture while allowing for a great deal of mobility

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T/F: Cervical curve is the least distinct of spinal curves?

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The part of the spine is considered to have a secondary (compensatory) curve

Cervical

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What does the upper cervical spine consist of?

Occiput
Atlas
Axis

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What is the most complex region of the axial skeleton?

Upper cervical spine

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What are the 2 articulations of the upper cervical spine?

Atlanto-occiptial

Atlanto-axial

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T/F: there is no IVD at the articulations of the upper cervical spine?

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What types of motion are the the Occiput -C1 articulation?

Combined øx -25 degrees
one sided øz - 5
one sided øy - 5

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What types of motion are the C1-C2 articulation?

combined øx - 20 degrees
one sided øz -5
one sided øy -40

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What are the important muscles in the upper cervicals? (6)

rectus capitis post. major
rectus capitis post. minor
rectus capitis lateralis
recuts capitis anterior
sup. oblique
inf. oblique

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What are the stabilizing ligaments of the upper cervicals? (7)

transverse ligament of atlas
alar lig
PLL
Post. atlanto-occipital membrane
Ant. atlantooccipital membrane
ligamentum nuchae
apical lig

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What is the shape of the Superior Articular Process of atlas?

peanut shaped

concave

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T/F: The “cuplike” structure at C0/C1 in both the sagittal and frontal planes allows for ALOT of rotation.

F: this allows for little rotation

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The shape of the articulation of C0/C1 favors what axis of rotation?

øx (flexion-extension)

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X Axis Rotation of the C0/C1:
Flexion is limited by?
Extension is limited by?
What is the Range?

F: post. neck muscular tension
E: subocciptial muscle compression against the occiput
Range: mean value b/w 14-35 degrees

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Y Axis Rotation of C0/C1:
limited by?
range?

limited by:
- ant. and post. walls of C1 sockets
- joint capsule tension
- alar lig tension
Range: 4-8 degrees (each side)

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Lateral flexion under physiological conditions has not been systematically demonstrated and studied of this axis rotation.

Z axis rotation

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How is Z axis rotation induced at C0/C1?

One condyle elevates out of its socket, while the other serves as a pivot. Both condyles slide up their walls.

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What is the Range of Z axis rotation at C0/C1?

4-11 (induced in cadavers)

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What ligament limits z axis rotation of C0/C1?

alar lig

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The small amount of z axis rotation that occurs at the C0/C1 is typically associated with some small degree of what?

coupled rotation in the opposite direction, leading to the rotation of the chin away from the side of lateral flexion

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What is the shape of C1 inferior articular process?

oval
flat or slightly concave
faces slightly medial

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Even though the inferior facets of C1 may be flat or even concave, the configuration of the cartilage creates what type of articulation?

biconvex

X Axis Rotation: C1/C2

Biconvexity: Combined øx = 20 degrees

Increasing the curvature of the dens does what?

increases the amount of øx

What is IAR?

Instant Axis of Rotation: a path that identifies where one body will rotate relative to another body at a given instant in time.

What is the role of C2?

transmit the axial load of the head to the cervical spine and permits lots of Y axis rotation

T/F: at the limits of rotation, the lateral atlanto-axial joints are almost subluxated?

What lig restrains Y axis rotation at C1/C2?

Alar lig

What is the Range of y axis rotation at C1/C2?

43 degrees + or - 5.5 degrees

What articulation produces over 50% of the rotation of the neck?

Y axis rotation of C1/C2

Where are intraarticular meniscoid found?

With in the spaces where the surfaces of the articular cartilage diverge anteriorly and posteriorly of C1/C2.

These serve to keep a film of synovial fluid applied to surfaces of the articular cartilage that are not in contact with one another of C1/C2.

intraairticular meniscoids

When are intraarticular meniscoids of C1/C2 displaced?

They are displaced with Y axis rotation and passively return when neutral position is resumed

øy is coupled with y translation at what articulation?

C1/C2

Why is C1/C2 øz limited to 5 degrees?

alar lig and bony anatomy

Why is there little Z axis translation of C1/C2?

tight articulation of C1 ring around the dens

This axis of translation of C1/C2 is controversial and some claim that is doesn't exist.

X axis translation

C1 lateral bending has what effect on C2 motion?

it results in the rotation of the spinous process of C2 toward the convexity of the lateral bend (rotates to the opposite side)

Look at Tables of Cervical Flexion/Extension, Cervical Axial Rotation, & Cervical Lateral Bending (slide 59 -61)

coupled motion

Axial rotation about a longitudinal axis and lateral rotation about a sagittal axis are not natural or pure movement of the cervical spine. For this reason, they are always coupled with one another

During Flexion/Extension, there is associated translation in what plane?

sagittal

What is the total "normal" translation in mm?

3.5mm

Lateral bending causes spinous processes to move toward the convexity or concavity of the curve?

convexity

øx Arc of Curvature

The steepness of the arch while a vertebra moves from flexion to extension varies from vertebra to vertebra

What is the øx Arch at C2?

flat

What is the øx arch at C6 and C7?

Steepest arches *

T/F: The acuity of the arch increases with degeneration

F: it decreases

Motion limited by ALL

(-) øx [extension]

Motion limited by PLL

(+) øx [flexion]

Motion limited by Ligamenta Flava

slows the last few degrees of (+) øx [flexion]

Motion limited by Interspinous lig

(+) øx [flexion]

Motion limited by Ligamentum Nuchea

(+) øx [flexion}

Motion limited by Intertransverse lig

contralateral lateral flexion (øz)

What is the shape of the vertebral bodies of the cervical spine?

rectangular

What are the shape of the superior and inferior surfaces of the cervical vertebral bodies?

seller or saddle-shapped

In the cervical spine, X axis translation is ________, while X axis rotation is _________.

reduced; promoted

What limits pure lateral flexion to only a few degrees in the cervical spine?

uncinate processes; they serve as guides to couple lateral flexion with axial rotation

Possible synovial joint (synovial membrane w/ synovial fluid but no joint capsule) forming between the uncinate process and the superior vertebral body.

Uncovertebral joints

Degeneration of these joints is due to underlying DDD results in bony outgrowth (osteophytosis).

Uncovertebral joints

Degeneration of Uncovertebral joints my impinge what adjacent anatomy with disc bulge/herniation?

vertebral artery & cervical spinal nerves

What part of the IVD is thick and strong, binds to the anterior vertebral body, and acts like an interosseous ligament?

Anterior annulus

What part of the IVD is minimal if even present?

lateral annulus

What part of the IVD is only a concentrated central bunch of fibers?

posterior annulus

What is the cervical facet orientation?

teardrop-shaped synovial joints, angled at 45 degrees between coronal and transverse planes

What are the superior facet orientations of the cervical spine?

Posterior Superior Medial

What are the inferior facet orientations of the cervical spine?

Anterior Inferior Lateral

How mm thick is the articular cartilage of the "Z" joint prior to 20 years of age?

1-1.3mm

What happens to the "Z" joint with age?

Thins the articular cartilage Thickens the subarticular bone Osteophyte formation occurs

Sensory perception of movement or position within the body

proprioception

The IVD is innervated with what arrangement for proprioception?

circumferential arrangement | superficial to deep

What does the IVD likely sense (proprioception)?

peripheral compression/tension, deformation and alignment

Facet Mechanoreceptors reponde to _______ rather than mid-range of joint motion.

extremes

There are small or large numbers of mechanoreceptors found in the cervical facet capsules?

small ; but each receptor is likely responsible for a large receptive field

Sensory receptors within the belly of a muscle that primarily detect changes in the length of the muscle

Muscle Spindles

Muscles in the cervical region contain a high density of muscle spindles, especially in what muscles?

subocciptial muscles

What is the likely reason that the head and neck muscles have high spindle count?

head-eye coordination demands complex proprioceptive inputs form the neck muscles

The very high proprioceptive content makes the suboccupital musculature ideal for what?

ideal sensors of joint position and movements of craniovertebral joints

What suboccipital muscles has the most muscle spindles?

Rectus Capitis Posterior Minor (RCPMI) | 36 spindles/g

What is the "gate theory"?

Proprioceptive input flowing into the dorsal horn serves to disallow or modulate nociceptive input into the CNS - the more open the "gates", the more pain messages pass through. Therefore, the person experiences high levels of pain and vice versa.

This is a change in the stimulus-response profile of dorsal horn neurons so that they respond to mechanoreceptive afferents as if they were nociceptors (hurt may not equal harm)

Sensitization

Adjustments to decrease nociceptor input into the spinal cord seem to be an effective way to decrease what?

the hyper excitable central state

What are the muscular differences found in MRIs of individuals with chronic neck pain?

atrophy & fatty infiltration/degeneration

When does the cervical curvature develop?

prior to birth

What angle should the cervical lordosis be?

aprox 30-45 degrees | when measured between the lines drawn through C1 and C7

What does the Upper Cervical Curve consist of?

1. Occiput to Axis | 2. Concave anteriorly (aka Kyphotic)

What does the Lower Cervical Curve consist of?

1. C2-C7 | 2. Classical Lordosis

Is kyphosis a normal varient?

Not according to Deep Harrison (CBP)

What is the primary load on the cervical spine?

compression; shear component is only 10% of compression

What load is increased during flexion or extension in the cervical spine?

Compressive loads

Under what load does the spine remain tangential to the spinal curve, minimizing bending moments and shearing, while allowing the cervical spine to bear larger loads?

Follower Load

What load induces bending and shearing due to the formation of movement arms (levers)?

Vertical Load

The co-activation of the cervical muscles produces what?

follower load (NOT vertical load)

Biomechanics of the Cervical Spine Flashcards

(95 cards)