Exam 2: Lumbars Flashcards
Lumbar spine is largely responsible for
Trunk mobility
Inferior articular processes are ____ and face ____
Convex; anterolaterally
Orientation of inferior articular processes
AIL
Superior articular processes are ___ and face ____
Concave; posteromedially
Lumbar facets lie primarily in
Sagittal plane
Coronal at lumbosacral jxn
Sagittal facet configuration limits _____
Rotational flexibility
Sagittal facet configuration allows for greater mobility in
Flexion and extension
L1-L4 facets have ___ orientation and limit ____
Sagittal; axial rotation (thetaY)
L5-S1 facets have ___ orientation and limit _____
Coronal; P/A shear (z translation)
Lumbar facets normally carry ____% of axial load and up to ___% in extension
18% normally; 33% in extension
Primary movement in lumbar spine
Flexion/extension
___% of trunk Flex/ext occurs in lumbar spine
75%
Lumbar spine exhibits ___ times as much flexion as extension
2x
Lateral bending is coupled w/
Axial rotation
Spinous rotates to ___ side
Ipsilateral side
EXCEPT it may switch at L4/5
Nucleus pulposus in lumbar IVD are oriented
Posteriorly
Disc height to body height ratio =
1:3
The ratio gives disc greater
Resistance to axial compressive forces
Lumbar spinal canal contains/protects _____ proximally and the ____ distally
Lumbar enlargement (conus medullaris) proximally; cauda equina w/ spinal nerves distally
CNS is tethered to coccyx by
Filum terminale
Is the dural sac and its contents freely mobile?
No, Hoffman ligs stabilize them
Lumbar lordotic curve is a ____ curve
Secondary
Lumbar curve starts to develop
9-12 months of age (beginning to sit up)
Apex of lumbar curve
L3-4 disc
Normal lumbar lordosis should be ____ degrees
20-60 degrees
Sacral base angle increases with ant pelvic tils which results in
Inc in lumbar lordosis, and mor weight-bearing responsibility on facets
Sacral base angle dec w/ a posterior pelvic tilt which results in
Dec in lumbar lordosis, and more weight on disc
Dec in spines ability to absorb axial compression forces
Major stabilizer of L spine
Quadratus lumborum
QL is most active during
Heavy lifts (74%)
Isometric lateral bending (54%)
Standing isometric twists (42%)
ALL/PLL in lumbar spine restrict
Flexion/extension
This ligament provides stability by preventing excess motion btw vertebrae
Ligamentum flavum
Lumbodorsal fascia acts like a large
Extensor retinaculum: constrains long tendons of T/L extensors
Interspinous ligament controls what movement
Rotation
Also guards against posterior shear
Supraspinous ligament provides resistance against
Excessive forward flexion
Facet capsule restricts
Joint flexion and distraction of facet surfaces
Trauma causes ligament damage which causes _____
Joint laxity
Joint ____ follows joint laxity
Degeneration
Percent of adults that will experience low back pain sometime in their lives
80%
Back pain ranks second to ___ as most frequent location for pain
Headaches
Poor and constrained posture can lead to
LBP and muscle fatigue
Inc, asymmetric disc pressure
Stress/irritation of facet/ligaments
Most pressure on disc is in what position
Forward flexed (less than 80 degrees btw trunk and legs)
Extension increases
Tensile force at ant annulus
Loading/compression of posterior facets
Flexion increases
Posterior annulus tensile forces
Inc in AP shear on posterior facets
Static sitting/standing is concerning because of
Fatigue mechanisms
Human body requires movement to
Nourish structures (nucleus pulposus and IVD)
Dangers of sustained static posture
Creates stress at posterior annulus and PLL
Stress at posterior facet damages hyaline cartilage
Recommendations to reduce static compressive forces
Alternate sitting and standing
Change 20-30 minutes w/ 2 mins of movement in between
Spondylolisthesis is a defect of the
Pars interarticularis
Pars fractures are from
Posterior shear force to inf articular process
Repeatedly alternating flex/ext
Spondylolisthesis definition
Anterior displacement of vertebra
Spondys are usually at what level
L5 (67%)
Overall incidence of spondys
5-7%
Higher in males
Type I Spondy
Congenital
Abnormal neural arch
Type II Isthmic Spondy
Defect of pars interarticularis (stress fracture)
Isthmic spondy are MC in _____ patients and typically occurs at ____
Younger; L5
Type III degenerative spondy
Segmental instability secondary to advanced DDD
Degenerative spondy MC in ____ patients and typically occur at ___
Older; L4
Type IV Traumatic spondy
Fracture of neural arch, NOT pars interarticularis
Type V pathologic spondy
Osseous deformity secondary to pathology
Spondylolysthesis Grade I
0-25% slippage
Spondy grade II
26-50% slippage
Grade III
51-75%
Grade IV
76-100% slippage
Grade V
Spondyloptisis (VB falls of VB below it)
Burst fractures
Comminuted VB fractures, disruption of A and P walls
Burst fractures cause severe neurological problems from
Retropulsion of bone into spinal canal
Burst fractures result from high-energy axial load
Traffic collisions
Falls w/ great height/speed
Seizures
Fracture type w/ compression of Ant and middle column, posterior column intact
Burst
Type of fracture w/ anterior column intact, middle and posterior columns w/ distraction
Chance