Anatomy and Biomechanics of L Spine Flashcards
what composes the anterior column of the spine?
vertebral bodies
intervertebral discs
function of anterior column of the spine
hydraulic and WB
shock-absorption
what composes the posterior column of the spine?
articular processes
facet joints
purpose of posterior column of spine
gliding mechanisms for movement
what joints compose each spinal segment?
anterior: 2 vertebral bodies + IVD
posterior: 2 facet joints
which articular orientation facilitates axial rotation? blocks?
facilitates - horizontal
block - vertical
how are L spine facets oriented?
sagittal
what does the AMOUNT of available spine motion depend on?
disc-vertebral height ratio
compliance of fibrocartilage
dimensions & shape of adjacent end plates
age
disease
gender
what does the TYPE of available spine motion depend on?
shape & orientation of articulations
ligaments & muscles of segment
size and location of segment’s articulating processes
what is the largest avascular structure in the body?
intervertebral discs
C & L IVDs are thicker in the _____ portion
anterior
which segment’s IVDs are uniform?
T
which 5 stresses does IVDs resist?
axial compression
shearing
bending
twisting
combined motion
T/F: IVDs resists tension forces
F
what are the 2 types of stability of the spine?
mechanical - static
controlled - dynamic
what 3 components make up controlled (dynamic) stability of spine?
passive
active
CNS
which forces does the passive stability of the spine resist?
translation
compression
torsion
local ___ and global ____ = function
local mobility and global stability = function
what is the capsular pattern of the L spine?
SB = rotation then extension
which is larger in the L spine: spinous or transverse process
transverse
what is lumbarization?
S1 more mobile than normal
what is sacralization?
L5 fuses to sacrum
how are the facets of the upper L spine oriented? lower?
upper - sagittal
lower - coronal
T/F: the articular cartilage of the synovial joints of the L spine are avascular and aneural
T
normal intact disc: facet joints carry ____% of axial load
20-25%
when a disc is degenerated the facet joints carry ___% of axial load
70%
what positions in the facet joint tight in?
ALL
which structure can buckle during flexion of spine and lodge under the capsule which blocks extension and causes locking?
fibroadipose meniscoid
which structure s usually the 1st to be injured in the spine?
end plates
what are the 3 components of IVDs?
annulus fibrosus
nucleus pulposus
end plates
which part of the IVD has neurovascular supply?
outer 1/3
which forces does the annulus fibrosus transmit?
compression
shear
torsion
what are the 3 zones of annulus fibrosus?
outer: Sharpey’s fibers (fibrocartilage)
intermediate: fibrocartilage
inner: fibrocartilage (most cartilage)
which forces does the nucleus pulposus absorb?
compression and shear
T/F: there is no blood or nerve supply to the nucleus pulposus
T
how does the IVD get nutrients?
diffusion through the cartilaginous end plates
L5 tends to slide ___ and ___ d/t lumbrosacral angle
anterior and inferior
(where spondy more likely)
what motions does the ALL resist?
extension
excessive lordosis
what motions does the PLL resist?
flexion
traction
where is PLL weak?
lumbar
what motions does the lig flav resist?
flexion
when is lig flav slacked?
ONLY with extension
which ligament covers the z joints and is strongest in the L region?
lig flav
what motions does the interspinous lig resist?
hyper-flexion
what motions does the supraspinous lig resist?
hyper-flexion
what motions does the interspinous lig resist?
contra flexion (SB)
activation of ____ increases fascial tension of TL fascia and limits ____ & ____
transverse abdominis
mobility & anterior translation
coupled motion of ES
SB with ipsi rotation
which layer of the ES is most effective in SB
iliocostalis
which muscles are considered the rotator cuff of facet joints?
multifidi
(compresses and stabilizes)
which ab mm is a primary stabilizer and synergist of multifidi?
transverse abdominis
which mm gets short or atrophies in LBP pts?
iliopsoas
where do all lumbar veins drain?
inf vena cava
what is Schmorl’s node?
end plate fx in center when overloaded with axial compression
how much intradiscal pressure occurs in bending forward?
150%
how much intradiscal pressure occurs in lifting 20 kg weight w/ back bent and knees straight?
169%
axial distraction causes a creep of ___ mm immediately
1-2 mm
there is ___% lengthening of spine during traction d/t decreased lordosis
40%
there is ___% lengthening of spine during traction d/t separating of vertebral bodies
60%
during flexion of spine, there is ___ rocking and ___ translation
anterior rocking and translation
which structure has the largest resistance to flexion?
joint capsule
what motion causes the entire IV joint to be compressed?
extension
during axial rotation, there is gapping of the ____ facet joint and compression of the ____ joint
gapping - ipsi
compression - contra
which lig resist rotation?
inter and supra spinous
rotation in flexion increases the risk of injury to the _____
annulus fibrosus
SB is coupled with
rotation
during SB, the the ipsi facet slides ___ and the contra glides ___
ipsi - inferior
contra - superior
