Axial Skeleton Flashcards by McKenna Hunter

Why do different areas of the spine favor different motions?

the orientation of the facets allow for different motions in each area of the body (cervical, thoracic, etc)

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What 4 things does the axial skeleton do?

1) transmission of forces to the lower extremity during walking
2) supports body weight
3) protects
4) shock absorption from disks

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Why are the curves in our spine so important?

they help us absorb the compressive forces we endure; we’re 25% less effective at absorbing those forces without them

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Why are the transitional areas in the spine (ex: C to T, T to L) likely to break down easier for pts?

those areas are more subject to sheer forces and can develop bone spurs more quickly
these areas are more likely for patients to have pain

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T/F: Cervical and lumbar curves are primary curves.

false, secondary

- primary are thoracic and sacral

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What creates the lumbar lordosis in a developing child?

the psoas tilts pelvis forward during walking, creating the lumbar lordosis

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How are the curves physiologically able to form in a growing baby?

their vertebral bodies are half bone and half cartilage, they haven’t ossified yet
to get them to ossify, the babies need to weight bear

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At what age is the spine at adult proportions?

10 y/o

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Describe the line of gravity throughout the head to feet.

1) head: through mastoid/ext. acoustic meatus
2) thoracic: anterior to thoracic curve
3) hip: slightly posterior to hip, causing extension moment
4) knee: slightly anterior to knee: extension moment
5) ankle: anterior to ankle, dorsiflexion moment

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How does the spine change when we age?

decreased lumbar lordosis
increased thoracic kyphosis
increased cervical lordosis

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How can osteoporosis change the curves of the spine for women?

can cause an increased thoracic kyphosis, which can be compensated by a lumbar lordosis

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T/F: The long SPs on thoracic vertebrae limit flexion.

false, extension

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How are the thoracic vertebrae limited in motion? (by what bony anatomy?)

1) costal facets limit motion due to the articulation with the ribs
2) long SPs limit extension

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What spinous ligament resists excessive side bend on the contralateral side?

intertransverse ligament

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What ligaments resist excessive trunk flexion?

ligamentum flavum
interspinous ligaments
supraspinous ligaments
PLL

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What motion does the ALL resist?

hyperextension

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Describe the two parts of the IVD and their purpose.

nucleus pulposa = gel-like inner portion of disk, filled with H20, proteoglycans, and type II collagen
annulus fibrosis = rings of fibrous cartilage that contain the nucleus pulposa, helps distribute compressive forces

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At what time of the day is the disk most hydrated?

Right in the morning, since it regains water overnight and swells up

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What happens to the disk as we age? What is the “vicious cycle” that occurs?

nucleus pulposa dehydrates
this causes the disk to breakdown and vertebral bodies begin to touch, resulting in degeneration of the vertebral end plate
- b/c the vertebral end plate is broken down, now the disk won’t get its nutrients, so it breaks down even more - vicious cycle

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How do we prevent the degeneration of our disks as we age?

stay active
get lots of calcium
don’t smoke (prolongs healing time for disks, bad)

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T/F: Creams can help prevent disk degeneration.

false, but certain injections can

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How do intervertebral disks get nutrients?

end plates get peripheral blood flow, and then diffuse these nutrients into the disk
diffusion occurs from annulus fibrosis to nucleus pulposa

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What are the two nutrient sources for the disk?

1) blood vessels in the superficial annulus

2) blood in adjacent vertebral bodies

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What does a spinal motion segment consist of?

adjacent halves of two vertebrae, the disk in between, the related spinal canal and foramen

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Which is stronger, ALL or PLL?

ALL

What motion occurs in the frontal plane, and about what axis?

side bend, about the AP axis

What motion occurs about the ML axis?

flexion/extension, in the sagittal plane

What plane and axis does rotation occur in?

``` plane = horizontal axis = vertical ```

T/F: Facets are smaller in the cervical region and larger in the lumbar region.

true

If the facet orientation is parallel to the horizontal plane, what motion is favored?

rotation (like the C-spine orientation)

The cervical facets are at what angle with the horizontal plane?

45 degrees

What plane are the cervical facets parallel to, and what motion does this make them good for?

frontal, so really good for side bend

T/F: Cervical facets are equally as good at flexion/extension as they are at side bending.

false | - best at side bend, then equally good at rotation and flex/extend (since 45 deg from both horizontal and vertical axes)

In what direction do the cervical IAPs and SAPs lie?

``` IAP = inferior and anterior direction SAP = superior and posterior direction ```

What motion do thoracic vertebrae favor?

side bend, b/c they're so close (20 deg) to the frontal plane

Which way do the IAPs and SAPs face in the thoracic region?

``` IAP = anterior SAP = posterior ```

T/F: Thoracic vertebrae are better at rotation than flexion/extension.

true?

What areas of the spine are good for rotation?

cervical -> thoracic -> lumbar

Why is thoracic extension limited?

by the thoracic SPs and ribs

What directions do the IAPs and SAPs of the lumbar spine point to?

``` IAP = anteriolateral SAP = posteriolateral ```

What motion does the lumbar spine favor?

flexion/extension due to being nearly parallel to the sagittal plane

T/F: Lumbar facets are oriented 90 degrees from the horizontal plane.

true, making them not good for rotation at all

What kind of forces cause herniated disks?

shear and torque forces

What is spondylothesis?

when two vertebral bodies shear off

What structure helps control the compressive forces that the disk endures?

the annulus fibrosis evenly distributes the force about the disk so as to not have it

Where does a common spondylysis occur?

at L5 and S1, lots of shear forces here due to angle of lumbosacral joint

Do the facets gap or approximate in trunk flexion?

gap; they approximate in extension

What's the normal angle for the lumbosacral joint? How much body weight does this joint hold?

- 40 deg | - takes 64% of body weight; will do more if angle is increased

What structures are taut in flexion?

ligamentum flavum, interspinous lig, supraspinous lig, ligamentum nuchae at neck, PLL, posterior disk

What happens at the facets and joint capsules on both sides for L side bend?

L side: facet closes down, capsule compressed | R side: facet gaps, capsule stretched

T/F: When side-bending, the disk protrudes contralaterally towards the convex side.

true

Pressure loss in the nucleus of a disk can cause what?

disk collapse: delaminating stressing can pull annulus apart | - commonly found in older spines

What does the transverse ligament do?

holds down the dens

What ligament in the neck is the big ligament preventing excessive rotation?

alar ligament

What does the cruciate ligament do?

limit side bend and flex/extend, stabilize AA joint

What does the tectorial membrane do?

limits rotation and flexion (extension of PLL), stabilizes low C-spine

T/F: There is radial bulging both outwards and inwards during disc collapse.

true

What arthrokinematics are occuring at the AO joint during flexion? AA joint?

- AO = anterior roll and posterior slide of occipital condyles on their facets - AA = tilts forward

What arthrokinematics occur at the C2-C7 level during flexion?

IAPs slide superior and anterior on the SAPs

Which joint in the neck doesn't move much during motion?

AA joint

What arthrokinematic motions occur at each neck joint during side bend?

- AO = condyles roll toward side of bend and away on contralateral side - AA = minimal motion - C2-7 = ipsilateral IAPs slide inferior and some posterior, while contralateral IAPs slide superior and a little anterior

In what movement does the AO not do much?

rotation

What c-spine arthrokinematics occur with rotation?

- AO = not much - AA = ipsilateral IAPs slide posterior, contralateral slide anterior - C2-7 = ipsilateral IAPs slide mostly posterior, some inferior; contralateral IAPs slide mostly anterior, some superior

What happens with craniocervical spinal coupling?

- when low c-spine rotates R, it will also R side bend | - upper c-spine will also R side bend, but rotate L

Where does the AA joint have the most motion?

during rotation

T/F: The C-spine is naturally slightly protracted

true (flexed lower c-spine, extended upper c-spine)

What bony structures in the c-spine facilitate flexion and extension, but limit side bend?

uncinate processes

What motion opens up the IVFs?

flexion

The patient doesn't want to turn their head to the right because it's painful. What bony issue could be causing this?

stenosis on the right side: ipsilateral IVFs close down during rotation, so if it's painful to rotate to the right, it may be because of those IVFs

T/F: T-spine and L-spine move the same.

true THANK GOD

What arthrokinematics occur during extension at the t-spine?

same as C-spine: IAPs slide posterior and inferior to SAPs

What arthrokinematics occur during t-spine side bending?

ipsilateral IAP slides inferior, contralateral slides superior

What do the facets do in the t-spine during right rotation?

both right and left IAPs slide left (contralateral slide)

When rotating left, which facet gaps and which approximates in the L-spine?

ipsilateral side gaps, so L gap, R approximate

In rotation, what is the difference in arthrokinematics between L-spine and T-spine?

T-spine slides inferiorly and superiorly, while L-spine just gaps and approximates

In what motion does the coccyx tilt posteriorly?

nutation

How are the sacroiliac joints stabilized?

1) form closure = good bony articulation btwn joint, occurs with age (increased integrity of ligaments, bones have grown together) 2) force closure = comes from the erector spinae, multifidus, thoracolumbar fascia