Flashcards in Axial Skeleton Deck (77)
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)
What 4 things does the axial skeleton do?
1) transmission of forces to the lower extremity during walking
2) supports body weight
4) shock absorption from disks
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
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
T/F: Cervical and lumbar curves are primary curves.
- primary are thoracic and sacral
What creates the lumbar lordosis in a developing child?
the psoas tilts pelvis forward during walking, creating the lumbar lordosis
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
At what age is the spine at adult proportions?
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
How does the spine change when we age?
- decreased lumbar lordosis
- increased thoracic kyphosis
- increased cervical lordosis
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
T/F: The long SPs on thoracic vertebrae limit flexion.
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
What spinous ligament resists excessive side bend on the contralateral side?
What ligaments resist excessive trunk flexion?
- ligamentum flavum
- interspinous ligaments
- supraspinous ligaments
What motion does the ALL resist?
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
At what time of the day is the disk most hydrated?
Right in the morning, since it regains water overnight and swells up
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
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)
T/F: Creams can help prevent disk degeneration.
false, but certain injections can
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
What are the two nutrient sources for the disk?
1) blood vessels in the superficial annulus
2) blood in adjacent vertebral bodies
What does a spinal motion segment consist of?
adjacent halves of two vertebrae, the disk in between, the related spinal canal and foramen
Which is stronger, ALL or PLL?
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.