Lecture 2A: Lumbar Spine Anatomy Flashcards
Axial Rotation
horizontal articular surfaces
vertical articular surfaces
clarifier
footnote
horizontal structres favor axial rotation
vertical blocks axial rotation (i.e. lumbar spine)
note: facets of the lumba are oriented vertically in the sagittal plane
spinal motion amount of available motion is affected by?
- disc vertebral height ratio
- compliance of fibrocartilage
- dimention / shape of adj vertebral end plate
- age
- disease
- gender
type of motion available govered by
shape and orientation of the articulation
ligaments / mm
size and location fo the articulation
most available motion is in the____spine bc it has largest facets
Lumbar
what’s the largest avascular structure in the body?
IVD
5 major stresses that the IVD Can resist are:
- axial compression
- shearing
- bending
- twisting
- combinted motion
T/F IVD does not resist tension
T
What makes the cervical and lumbar segments more lordotic than thoracic and sacral?
IVD is thicker anteriorly
IVD is uniform in thoracic
CV junction
atlax, axis and head
CT junction
mobile lower cervical movement meets super stiff thoracic t-spine
note: upper cervical spine is more mobile than the lower
the most rotation occuring at a junction is at
Thoracolumbar junction
thoracic has a larger ability to rotate than lumbar
lumbosacral junction
mobile l spine meets stiff SIJ ..
LESS ROTATION
two types of spinal stability
mechanical (static) stability = when body is still (equilibrium)
conrolled (dynamic) stability
- passive system= resisting forces of translation, compresson and torsion (esp at end range)
- active system= mm coordination to control body relative to environment
- CNS= feedforward/feedback
function equals=
local mobility
global stability
if the passive system is damaged
active system picks up slack, hence fatigues quicker
open pack position of the lumbar spine
midway flx/ext
close packed position of lumbar s
full ext
capsular patter of lumbar s (limitations)
SB = Rotation, Extension
more info slide 13
lumbarization
(less common)
S1 more mobile
more info slide 13
sacralization
L5 fuses to sacrum
more info slide 13
how much axial load do the facets carry with a normal intact disc carry?
how about a degenerated disc?
normal = 20-25%
degenerated disc = facets take up to 70% of axial load
more info slide 14
anterior facet joint capsule formed by
facet joints are reinforced by__
anterior = ligamentum flavum
reinforced by: multifidus and ligamantum flavum
facet joints are tight in
ALL POSITIONS
how does the fibroadipose meniscoid “buckle”
buckles during flexion and “lodges” under the capsule
it blocks extension which causes acute “locking”
the structure that absorbs shock and distributes load (compression)
IV disc
Annulus fibrosus surrounds the NP with neurovacular supply to ___
attached to ___
transmitting (3) forces
____H20
- outer 1/3
- end plates
- compression, shear, torsion
- 60-70%
which AF zone bas the most fibrocartilage?
inner zone
Nucleus pulposus:
- % H20
- NO _
- Absorbs___ and__ forces
70-90%
NO BLOOD AND NERVE SUPPLY
absorb compression and shear
what structure isweak to resist compression?
end-plate b/c mostly has no blood/nerve
if the IV disc is avascular, how does it recieve nutrients?
by diffusion via end-plates (cartilaginous)
everytime there’s a compression/tracton to the spine, blood goes
away from bone and to disc via endplate
D/T lumbosacral angle, L5 tends to slide __and___
ant and inf
more info slide 20 (spondy)
greatest tensile strength in lumbar region, resisting extension and excessive lordosis
ALL
resistns flexion and traction and is weak in the lumbar region and causes HNP
PLL
resising flexion ; **slack only w/ extension
strongest in lumbar region
ligamentum flavum
posterior ligaments
interspionous ligament and supraspinous ligaments
resists hyperflexion
intertransverse ligaments
limit contrallateral flexion (side bend)
iliolumbar ligament
resist ipsilateral side bend and translation of L5
Superior band of iliolumbar ligament
prevents flexion
inferior band of iliolumbar ligament
taut in extension
posterior band of iliiolumbar ligament
prevents flexion and resist side bending at L4, stabilzing L5 from ant displacement
the activation of this mm increases fascial tension, causes limitation intersegmental mobility and ant translation
TA
(in relation to thoracolumbar fascia)
thoracolumbar fascia functions
- mm attach
- resisted segmental flexion
- assist transmission of extension during lifting
which mm is most effective in side bendig in the ES group?
iliocostalis
this mm is the “rotator cuff: of facet joint: produces compression force during contraction and will stabilize the facet joint
multifidi
review the slides
31-35
slide 31-35
during axial compression:
NP pressure rise and AF bulges (posteroir or posterior lat)
end plate bows foward vertebra and can fracture if the load is too quick (weakest)
Disc: squeez out H2o during axial compression and “shortens”
T/F facet joint sustains verticlaly applied load in neutral position
FALSE
severe axial compression overtime will lead to fatigue failure.
more info slide 37
intradiscal pressures
bending fwd and lifting 20 kg weight w/back bent and knees straight
lifting 20 kg weight w/ back straight and knees bent
150%
169%
73%
facet joints are strong during ____
traction
creep 1-2 mm immediately
lenghening will cause flattening of lumbar lordosis curve
“opening” movementof the lumbar spine is
flexion occurs in all segments except
anterior rock + anterior translation
L5-S1
flexion is restained due to
joint capsule (mainly)
IV disc
this motion increases the risk of damaging annulus fibrosus
rotation in flexion b/c facets are minimal contact
axial rotation restrains
interspinous and supraspinous lig
interspinous ligament buckles b/t SPs during
extension
read the last couple of slides
