Cervical and thoracic regions Flashcards
What are the primary and secondary curves of the spine?
Primary:
- kyphosis (thoracic and sacral)
Secondary:
- Lordosis (cervical & lumbar)
What happens to the cervical curves during sagittal plane movement?
Flexion: decrease/flatten out lordotic curve
Extension: increases lordotic curve
What happens to the thoracic curves during sagittal plane movement?
Flexion: increases kyphotic curve
Extension: decreases/flattens out kyphotic curve
What happens to the lumbar curves during sagittal plane movement?
Flexion: decrease/flatten out lordotic curve
Extension: increases lordotic curve
What happens to the sacral curves during sagittal plane movement?
- Fixed, fused together so doesn’t move
What is one negative of having spinal curves?
- shear forces
- can lead to spondylolisthesis
Where does the LoG fall for each spinal curve?
- falls on the concave side of each curve
- Anterior = kyphotic
- Posterior = lordotic
Is it a good thing or bad thing that the LoG falls on the concave side of each curve?
- Good!
- helps keep curves in line & decreases work needed from ligaments/muscles to maintain good posture & ideal LoG
What are anatomical factors for ideal posture?
- shape of discs or vertebral bodies
- facet joint orientation
- ligament composition
- muscles stiffness
What happens to the PLL as it descends through the lumbar spine?
- it starts to narrow as it moves down
How does the narrowing of the PLL affect the discs in the lumbar region?
- hard to stop a bulging disc which leads to increased chances of bulging disc injury
Describe a “motion segment” and its components
Segments of the vertebral column that allow movement
- transverse & spinous processes
- apophyseal joints
- interbody joints
Define osteokinematics as it relates to movement at a spinal motion segment
- 3 degrees of freedom
- AoR through interbody joints
- movement is described by what the joint is doing and where the front goes
Define arthrokinematics as it related to movement at a spinal motion segment
- describes motion of the facets
- sliding, gapping, approximation
Define the AoR as it related to movement at a spinal motion segment
- interbody joint is the AoR
What are the functions of the interbody joints?
- absorb & distribute loads
- glues vertebrae together
- approximate axis of rotation
- discs = spacers
What are “intra-articular inclusions?”
- small, accessory structures that exist around joints
EX: subscapular fat pads & fibro-adipose meniscoids (FAMs)
How can these intra-articular inclusions affect facet joints?
- fill up spaces b/w facet joints
- help dissipate compressive forces
- partially cover articular cartilage
- FAMs can become impinged during whiplash
- can lock facet joints
What facet orientation allows for different kinds of movement?
- more vertical facet orientation = more frontal/sagittal plane movement
- more horizontal facet orientation = more axial rotation
What part of the intervertebral disc has nerve and blood supply?
- annulus fibrosus -> outer layer innervated/vascularized
How does the annulus help dissipate loads?
- comprised of collagen & elastin w/ layers
- alternates orientation w/ each layer
- oriented 65 degrees from vertical & 25 degrees from horizontal
How does the disc get nutrition?
- diffusion
Why are we taller in the morning than in the evening?
- disc swells overnight
Why would a disc be more painful in the morning?
- weight-bearing compresses disc & pushes water out
- painful for those w/ issues
Explain the process of disc degeneration
1) Aging, excessive, or abnormal mechanical loading -> reduced permeability & increased calcification of endplates
2) reduced nutrient flow to disc
3) Inhibition of cellular metabolism & proteoglycan synthesis -> can’t attract & retain water -> decreased ability to absorb & transfer loads
How does the disc help transmit loads through the spine at each motion segment?
- endplates move toward nucleus
- nucleus slowly deforms radially (which is incompressible)
- annulus resists radial deformation
- pressure transmitted to other vertebra
How does the disc respond to movement of the spinal motion segments in the sagittal plane?
Flexion:
- compression anterior
- stretches posterior
- nucleus migrates posterior
Extension:
- compression posterior
- stretches anterior
- nucleus migrates anterior
How does the disc respond to movement of the spinal motion segments in the frontal plane?
Lateral flexion:
- compression ipsilateral
- stretches contralateral
- nucleus migrates contralateral
How does the disc respond to axial compression?
- resisted by discs & vertebral bodies
- transmitted through discs to end plates to vertebral bodies
How does the disc respond to bending?
- compression 1 side
- tension other side
- nucleus migrates away from compression
- creep of viscoelastic structures
How does the disc respond to torsion?
- resisted by vertebral bodies, discs, facets
- annular fibers rupture w/ torsion & axial compression & forward bending
How does the disc respond to shear?
- vertebral translation
- resisted by facets & discs
- disc creep leave facets only to resist
Explain the spinal coupling that occurs in the mid-lower cervical spine
- lateral flexion + ipsilateral rotation
What happens if the transverse ligament of the atlas is ruptured?
- Dens is free to move which could injury spinal cord
- atlas slips anteriorly