Lumbar Spine Flashcards
Thoracic curvature purpose
make cavity for organs
If lumbar was straight… with no curvature then what
The torque we would experience above would be enormous because the moment arm of the curvature we have in the thoracic region would be larger than the lumbar region
Moment arm would be double so for the same load, we would have twice the torque
Main role of cervical and lumbar curvatures
reduction of the torques (by reducing the moment arm of superincumbent weight)
Anatomy of the spine
Extends from base of skull to pelvis
32-33 bones (vert)
Protects spinal cord
Structural support and linkage to extremities
Cervical Thoracic Lumbar Sacrum Coccyx
C1 - C7 T1-T12 L1-L5 5 fused bones 3-4 fused bones
Primary vertebral curves
Thoracic
Primary = visible before birth
Secondary vertebral curves
Cervical and Lumbar
Secondary = develop later and take their final shape because of gravity
Lumbar is greater in F than M because of breasts - larger to reduce the effect of superincumbent weight
Body
Anterior potion, thick, dense, contains most of the vertebral mass (cortical - outer, cancellous - interior matrix)
Arch
Posterior portion with several finger like projections (processes)
Processes
Place for attachment for tendons and ligaments
7 total for typical (1 spinous, 2 transverse, 2 sup articular, 2 inf articular)
Pedicles
short round process of thick strong bone linking the anterior and posterior portions
Spinal canal
houses the spinal cord, providing protection from external forces
Purpose of processes
attachment purposes, muscles ligaments and interact btw two consecutive vertebrae to give you joints
Shape ans size have effect on the effectiveness of the structure attached to them
Longer - maybe longer moment arm
Structure of vertebrae
characteristics change all along the vertebral column even within the same region
The lower you go down - the larger the body will be (they have to deal with more gravity)
The way that the facets and processes face is important for their function in respect to motion
Spinal cord
part of CNS extends from brainstem to L1 Relays infor to and from skin, muscles, ligaments, organs, joints Ant nerve roots = motor Post nerve roots = sensory
Cartilaginous joints
Intervertebral disks - btw bodies of vertebrae from cervical to sacrum
Gliding (facet) joints )articular processes)
Articular capsules are loose and thin (so capsule is not limiting the joint)
Segmental mobility is related to the orientation of the gliding joints
Facet joints are diathroses synovial (allow movement, synovial cavity, synovial fluid)
Intervertebral discs
separate the vertebrae
absorb stress and shock
enable multiplanar motion in spinal column
Intervertebral discs cont
Composed of…
fibrocartilage transverse shape conforms to the disk bodies Thickness is not uniform 25% of length of vertral column Allows motion in all 3 planes
Composition of intervertebral disks
nucleus pulposas (gel like mass) = semi fluid jelly of proteoglycans in water Annulus fibrosus (fibrocartilage that encases the nucleus) = collagen fibers arranged in criss cross fashion These allow the disc to withstand greater tensile and rotational forces
Intervertebral disk degeneration
Degeneration with age
Reduction of elasticity
Inability to resist loading/dampening
Motions of ID and and Vertebrae
12 segmental motions
Translations –> Ant/Post, Lateral (left/Right) and vertical (compr/distract)
Rotations –> Ant/Post, Lateral tilt (Left/right), Lateral rotation (left/ right)
The thicker the intervertebral disc…
the larger the movement will be
Effect of bending - backward bending moment
Ant = tension
Post = compression
Annulus bulges = posterior
Nucleus shifts = anterior
Effect of torsion - torsion moment
Shear stress increases from the center to the periphery
Facets
Change orientation from cervical to lumbar regions
Articular joints allow smooth articulation btw vertebrae
Resist motion through bony interactions, aided by ligaments
More on Facets…
Shape is diff at thoracic and lumbar regions
Thoracic AP direction is longer than in ML direction
Lumbar ML is longer than AP
Longer the direction, the more stability
Facet is covered by hyaline cartilage
Facet and lumbar region
Facet orientation does not allow rotation at lumbar region
Facet orientation changes from cervical to lumbar
Lumbar region motions
Ample flexion/extension and nc as go from top to bottom of lumbar region
Lateral flexion is allowed but is less and is consistent throughout levels (limited at lumbosacral joint)
Rotation is very limited - little more at lumbosacral joint
Joint coupling
If it is not a pure motion, it is joint coupling
Side bending and lumbar rotation
Side bending can’t occur without some lumbar rotation
Lumbar spine in neutral or extended position
Side bending and rotation in opposite direction
Lumbar spine in flexed position
Side bending and rotation in same direction
Cervical Vertebrae C3-C7
Facets 45 degrees
FL-EX (sagittal plane)
Lateral flex (frontal)
Rotation (transverse)
Thoracic Vertebrae
Facets 60 degrees
FL-EX (limited), higher at lower part
Lateral flexion, same all across
Rotation (mostly)
Lumbar vertebrae
Facets 90 Degrees
FL-Ex
Lateral flexion (limited)
No Rotation
Anterior Longitudinal Ligament
From axis to sacrum
Adheres to disks and prominent margins of vertebrae
Strained during extension
Holds disks in place with vert bodies
Posterior longitudinal ligament
from axis to sacrum
Posterior of the bodies inside the vertebral canal
Contributes to stability in the intervertebral joints
Ligamentum Flavum
From axis to sacrum
Connect adjacent laminae
Strained during flexion and lateral flexion
Limits contralateral flexion (R will be stretched when leaning L)
Supraspinal Ligament
C7 to sacrum
Tips of spinous processes
Strained during flexion
Btw two consecutive spinous processes
Interspinous Ligament
btw spinous processes
Strained during flexion
Capsular ligaments
Ligaments of the capsule of facet joints
Strained during rotation
Transverse ligaments
btw consecutive trans processes
Strained during rotation and lateral bending in opp direction
Iliolumbar ligaments
L4/L5 trans processes to iliac bone
Offer stability
Strained during rotation and lateral bending
Most ligaments limi
flexion
abdominals do a good job of limiting extension
Lumbosacral or Ferguson’s Angle
angle formed by the line parallel to the sup aspect of the sacrum and the horizontal
Lumbosacral angle on sagittal plane Range observed and typical
Observed = 26-57 deg
Typical = 35-45
Hyperlordosis = > 45
Hypolordosis =
High lumbosacral angle =
high anterior convexivity of lumbar spine = high shear stress at lumbosacral joint = larger lumbar curvature = anteriorly rotated
Lower lumbosacral angle
posteriorly rotated
Flexor Muscles
Rectus Abdominis IO EO TA Psoas Muscles
When a muscle is producing force… its fibers will
become shorter
External Oblique fibers
superior and lateral to inferior and medial
EO Action
laterally flex to same side
rotate to opposite side
Internal Oblique fibers
inferior and lateral to superior and medial
IO Action
laterally flex to same side
rotate to same side
IO and EO together will
Tighten the abdominal region and pull in abdominal organs
Can also help into flexion - more when in supine than in standing
Right EO is activated so…
laterally flexing to the right
OR
rotating to the left
Rotating to the right activates what
Left EO Right IO
Transverse abdominis fibers
transverse
TA action
tighten organs in abdominal cavity
Rectus abdominis fibers
short fibers that are compartmentalized –> FL/ML ratio that is small so force muscle –> strong
Rectus abdominis goes from
pubic symphysis to sternum and ribs 67
Action of RA
flexion of trunk - best when in supine to flex from lumbar vertebrae
RA also has largest MA in terms of producing flexion at lumbar spine
Psoas Major
Assisted by iliacus
Crosses lumbar and hip joints
Pulls on lumbar region and counters the tendency of the motion of the femur and pelvis?
Hip flexor
Psoas Minor
Crosses only lumbar region Stops at pelvis Posterior pelvis rotation extends lumbar region in a way Hip flexor
Extensor Muscles
Erector Spinae (9 muscles 3x3 on each side) Semispinalis (CA, CE, T) Multifidus Rotators (CE, T, L) Interspinales Intertransversarii
Erector Spinae
Spinalis (Ca, Ce, T)
Longissimus (CA, CE, T)
Iliocostalis (CE, T, L)
Erector Spinae Spinalis
very tightly related to vertebrae
Parallel to spinous processes of vertebrae
Erector Spinae Longissimus
A bit lateral to spinalis
Erector Spinae Iliocostalis
Even more lateral than longissimus
Erector Spiane Muscles bilaterally
extend the vertebral column
Active in flexion though because they are resisting flexion and controlling it
Erector Spinae Muscles unilaterally
not much of an ability (spinalis)
long and ilio - more of an action
Lateral flexion and rotation ipsilateral for both
Iliocostalis is most effective
Multifidus
span more than one level more efficient than rotators in action of rotation orientation like an x-mas tree unilateral rotation - contralateral Any flexion would be ipsilateral
Semispnalis
no effect on lumbar region
Rotators fiber orientation and action
sup and med to inf and lateral
rotation is contralateral under unilateral activation (pull spinous process closer to inf transverse process)
They are more stability muscles than rotators
Quadratus Lumborum
attached to last pair of ribs and trans processes of all lumbar vertebrae and iliac
Quadratus lumborum action
Stability muscle!
Active in any motion of lumbar region
Works as a brace and braces the lumbar region and creates stability in everything that we do
Unilateral - limits contralateral flexion
Interspinalis
muscle fibers invested in and around interspinal ligament btw consecutive vertebrae
Resist flexion
Intertransversarii
Help quad lumborum
MA is small but segmentally can produce support from both sides
Unilaterally = ipsilateral flexion and resist contralateral flexion
Flexion-Relaxation Phenomenon
Posterior Trunk muscles Increase lumbar curve Produce extension Initiate hyperextension Control forward flexion
What controls flexion at extreme forward flexion ranges
passive elastic response of the thoracolumbar fascia and the posterior ligamentous system
Flexion forward - erector spinae
active for the first 30 degrees and their activity becomes less and less
in a specific range, erector spinae resist flexion, but past that point won’t be functinal anymore - lumbosacral fascia is helping and the fascia will be effective forever - like aligament in that it can elongate a ton
Shear and Compression force
Compression = perpendicular Shear = parallel
Pelvic orientation - larger the lumbar curvature with ant tilt
the larger the shear
Pelvic Orientation with shear and compression - post tilt
compression forces are high
Pelvic orientation with shear and compression - ant tilt
shear forces are high
What forces contribute to load we feel at the joint
Body weight above the joint Weight itself of what you are picking up Moment arms Erector Spinae muscle force Motion - inertia
Load on spine Laying down Sitting Sitting slouched over Standing Standing slouched over
Laying = less than 50 Standing = 100 Sitting = 150 Standing slouched = close to 150 Sitting slouched = close to 200
Why higher load on spine when simply sitting?
You are in a slight ant rotation so this is increasing lordosis
Spondylolysis
separation of vertebra
L5 S1 is most common but can also be found at L4 L5 lumbosacral junction
Spondylolisthesis
forward movement of vertebral body
LBP
75-80% of pop will experience Mechanical stress plays significant role Pregnancy Relative stbaility of spne 60% are idiopathic Abdominal exercises are helpful treatment
Two common causes of LBP
Compressive or neurogenic = symptoms are referred due to spinal nerve compression
Mechanical = localized pain due to damage to facets, discs, or soft tissue
Lifting recommendations
Bend knees
Keep weight close to hips
Avoid lifting while twisting (places 3 times more stress on spine)
Avoid rapid, jerking motion while lifting
