Lumbar Spine and Sacrum

Spinal stability by lumbar ligaments Supraspinous ligament

resist flexion resist seperation of spinous processes

Spinal stability by lumbar ligaments Posterior longitudinal

resist flexion restrict vertical seperation of posterior vertebral bodies

Spinal stability by lumbar ligaments interspinous ligament

resist flexion resist posterior translation of superior on inferior resist seperation of posterior vertebral bodies

Spinal stability by lumbar ligaments Ligamentum Flavum

resist flexion resist seperation of lamina during flexion

Lumbar facet joints -facets face __________ -allows ___ limits____ -resists what 2 forces?

synovial, joint capsule, ligamentum flavum anterior support -facets face medially and with curved shape of facet joint (in sagittal and frontal planes) -allow flexion/extension motions mostly, some lat bend -limit rotation -resist compresion forces -resist anterior shear forces (by the frontal plane orientation and the tension in the joint capsule

straight leg test implications

tibial and sciatic nerves lenghten, causing tension to lumbosacral nerve roots to spinal cord. if there is pain there may be a nerve compression, inflammation of disc herniation

lumbopelvic rhythm: extension (return from flexion)

beginning phase: Mostly extension of hips (posterior roll of pelvis) due to strong activation of hip extensors (glut max + hamstrings) middle phase: hip extensors and lumbar extensors equally (both concentric) late phase to completion: required muscle force decreases and muscle activity ceases when line of force from body weight falls posterior to hip, balanced.

Influence of lifting technique on loads at the Lumbar spine

bending back over forward w/ knees straight: require more extensor muscle activation to counteract the larger flexor moment of the weight of the body and the box (due to larger MAs) Holding box further out in front of body while bending knees and back: increases MA and flexor moment of box and body, requires more force also. back upright, bending knees holding box near body: shortens MA of weight of body and of the box. Will reduce loads on Lumbar spine (extensors need less force), safer

SI joint motions Nutation:

-base moves anteriorly -apex moves posteriorly -in trunk flexion or bilateral hip flexion (anterior sacral tilt with posterior iliac tilt)

SI joint motions Counternutation

-base moves posteriorly -apex moves anteriorly -in trunk extension (posterior sacral tilt with anterior iliac tilt)

Lumbar Intervertebral discs

-concentric ring of fibrocartilage layers for Annulus fibrosis -gel like nucleus puplosus

Forces at the SI joints: a. Position your lab partner supine and apply a posterolateral directed force to bilateral ASIS - b. Position your lab partner side lying and apply a lateral to medial force over the iliac crest/pelvis c. Position your lab partner supine. While standing at side of your lab partner, flex hip on opposite side to 90 degrees (with bended knee). Place 1 hand beneath the sacrum while other hand is used to apply a downward directed force along the long axis of the femur d. Position your lab partner prone. Place one hand over sacrum with other hand over top for reinforcement then apply a downward directed force

-distraction force at anterior aspect of SI joint - compression force at SI joint - posterior shear of ilium relative to sacrum -anterior shear of sacrum relative to ilium

superior articular facets of sacrum

-superior articular facets on superior articular process are vertically aligned and project posteriorly and medially to articulate with inferior facets of L5 to resist anterior shearing force

Sacrum apex vs base: apex articulation: sacral hiatus: sacral promontory:

5 fused segments (fuse at age 5 to about 20) Base on top, narrower apex on bottom -apex articulates with 1st coccygeal segment -sacral hiatus: most caudal anchor of spinal cord -sacral promontory resists anterior shearing of L5 relative to S1

Coccyx

3-5 fused vertebrae, most inferior of vertebral column -IVD btwn S5 and S1 -Curvature follows curve of sacrum (convex posteriorly) -no physiological importance in weight transfer -site for muscular attachements

Sacroiliac joint anterior ___ joint between _________ posterior ___ joint between ________ -type:

Anterior Synovial joint btwn iliac and sacral auricular surfaces and a posterior syndesmosis joint btwn their tuberosities. -has a joint capsule, fluid filled cavity, interosseus membrane and tuberosities -Plane joint even though not flat smooth surfaces

Intervertebral disc in forward bend/flexion:

Anterior roll of the superior vertebrae will increase the compressive forces at the anterior aspect of the disc. -Nucleus of disc will translate posteriorly and cause more expansion of posterior elements of the disc

curvature of vertebral column

Cervical - lordosis thoracic - kyphosis lumbar - lordosis

Arthrokinematics: lumbar rotation

Contralateral facet joint: approximation/compression of joint surfaces Ipsilateral facet joint: separation/distraction of joint surfaces SP move to opposite side

Arthrokinematics: lumbar lateral flexion

Contralateral: superior slide (of inferior facet of the top vertebrae) and distraction of joint surface Ipsilateral: inferior slide and compression of joint surfaces

Arthrokinematics: lumbar extension facet joint slide: vertebrae roll: IVD: slack on ______, tension on ______ vertebral foramen size: muscles:

Extension: inferior/posterior slide at facet joints (sup on inf) causing decreased contact of articular surfaces posterior roll of superior vertebrae on inferior compression at posterior aspect of IVD causes nucleus to displace anteriorly slack on posterior ligament and facet joint capsule tension on anterior longitudinal ligament dec size of intervertebral foramen hip flexors eccentric

Spine stability: muscle stiffness (2 groups of muscles contract) -abdominal muscle contraction: - increases _________________ which increases the ______________ moment leading to a stiffer spine -increases spine _______ loads -increases ______ of spine

Extensor muscles + abdominal muscles stiffen spine when contract Activating a muscle increases stiffness of the joint and muscle -abdominal muscle contraction increases intraabdominal pressure and increases extensor moment leading to a stiffer spine by the creation of a "corset". - increases spine compression loads -increases stability of spine -too much muscle contraction leads to too much stiffness and increased compression forces -too much stiffness will also limit joint motion -need balance for stability + motion by proper level of contraction

Arthrokinematics: lumbar flexion facet joint slide: vertebrae roll: IVD: slack on ______, tension on ______ vertebral foramen size: muscles:

Flexion: superior/anterior slide at facet joints (sup on inf) causing decreased contact of articular surfaces anterior roll of superior vertebrae on inferior. compression at anterior aspect of IVD causes nucleus to displace posteriorly slack on anterior longitudinal lig tension on posterior ligaments and facet joint capsule inc size of interverterbal foramen hamstrings eccentric

Stability at SI joint: 3 stabilizing effects of ______ torque (CPP)

Greatest stability in close-packed position in nutation: stabilization effects in nutation -weight of body and gravity: cause posterior rotation of pelvis, causes sacrum to nutate for stability - stretched ligaments: tension on sacrotuberous and sacrospinous ligaments in nutation -Active muscle force: contraction of rectus abdominus, biceps femoris and erector spinae

sacrospinous ligaments _________ to ____________ -superficial fibers blend w/ __________ ligament - deep fibers blend w/ ___________ muscle -converts____________ -resists

Ischial spine to lower sacrum and cocyx -superficial fibers blend with sacrotuberous ligament -deep fibers blend with cocygeal muscle -helps convert notches into foramen -resist nutation

Intervertebral disc function in dispersing compression hoop stress: pascals law: radial expansions:

L spine subject to extreme compression loads down spine due to gravity when standing, discs help disperse the forces btwn the bodies (remove forces before getting to next body) -"hoop stress": refers to the conversion of vertical compressive forces into circumferentially applied tension; discs dissipate the forces circumferentially -"pascal's law": refers to pressure applied to a confined incombressible liquid being distributed in all directions; forces dissipate equally in all directions -"radial expansion": compresssion force causes nucleus to exert pressure against the surrounding annulus fibrosis causing bulging. the annulus fibrosis will expand as it absorbs forces

Influence of size of object on loads at lumbar spine -larger box (but same weight) will have ____________moment due to a _____MA -will require more ____________force

May be same weight box but if larger it will have a greater flexor moment due to a longer MA so will require more extensor force to hold without falling forward.

Intervertberal disc pressures during daily activites flexion vs extension of L spine: lying down vs standing vs sitting and flexing: effect of reclining: effect of lumbar support:

Overall less pressure on discs in lumbar extension (lordosis) and more when in lumbar flexion (kyphosis) lying down: lower compressive forces standing: more compressive forces flexion: increases intervertebral disc compression forces than if sitting/standing upright. most when stand and flex -disc pressure decreases as you recline/extend spine -apply support at lumbar area when sitting facilitate extension of L spine and increase the lordosis to decrease pressures at discs. -but support up in head area will cause kyphosis of L spine and inc disc forces

movement system impairments related when fracture pars interarticularis and causing anterior slip/step off

Passive, Neurtral and Active Stability and Mobility -excessive anterior translation of L5 so need more posterior shear forces by erector spinae muscles -need more stability by extensor muscles and abdominal muscles - excessive motion/hypermobile at that location but stiffer around it.

Long Posterior (dorsal) Sacroiliac ligaments -size/location -long vs short fibers: -resists:

Stronger and more extensive then the anterior SI ligaments (longer/vertical down pelvis) Long fibers superficial and short fibers deep to them Resist counternutaion (sacral counternuration and ant pelvic tilt)

Spinal stability by lumbar ligaments Anterior longitudinal

resist extension resist vertical seperation of anterior vertebral bodies

iliolumbar ligaments

Ventral and Dorsal Bands Ilium to TP of L5 limits anterior shear of L5 relative to sacrum provides stability at L5/lumbosacaral junction

Sacral Inclination

angle of inclination between the sacrum and the horizontal -average = 30 deg -range: 20-90 deg varies with pelvic positioning greater in females increased sacral inclination = increased lumbar lordosis (inc ant shear force)

ant pelvic tilt muscles post pelvic tilt muscles

ant pelvic tilt: concentric quads and erector spinae (extend spine, flex hips) post pelvc tilt: concentric hamstrings and abdominal (flex spine, extend hips) (concentric are short/tight, the opposites stretch/lenghten

Standing with inc lumbar lordosis will inc the amount of _____ shear forces on the lumbar spine, especially at L5-SI. What prevents the L5 vertebrae from sliding off S1 in the ______ direction? ligaments, joints,bone areas and muscles

anterior shear forces, sliding off in the anterior direction -anterior longitudinal ligament limits ant translation of the body -interspinous ligament resists anterior translation of L5 relative to L4 (limits posterior translation of the sup on inf) -iliolumbar ligaments limit ant translation of L5 relative to S1 -compression at lumbosacral facet joints - sacral promontory -posterior shear forces by erector spinae -active contraction of lumbar spine (abdominal and extensors) muscles to inc compressive forces for stiffness/stability

Thoracolumbar Fascia

connective tissue originating from thoracic, lumbar and sacral spinous processes. ant, mid, and post layers -creates corset hoop around abdomen with abdominal fascia -supports spine in flexion, inc stiffness + stability as muscles tense and pull it -gives rise to Latissimus dorsi and gluteus maximus which tightens it for stability in X shape compression -also attaches to psoas major, quadratus lumborum, erector spinae, and multifidus which contract for stability/stiffness

Effects on Lumbar curvature Forward flexion: Extension: anterior pelvic tilt (sit and stand) posterior pelvic tilt (sit and stand)

dec inc sit = inc, stand = dec sit = dec, stand = inc

spondylosis spondylolysis: spondylolisthesis:

degeneration of vertebrae/discs fracture at pars interarticularis anterior slipping of one vertebrae over the other (may or may not be due to spondylolysis)

Intervertebral disc in rotation

discs less tolerable to torsional/rotational forces: Annulus fibrosis has obliquely arranged fibers so only a portion of the fibers are taught -IVD is protected by the sagittal plane orientation of the facet joints which limit rotation in Lumbar spine -if flex spine, facet joints wont block rotation as much, facets open, allow more rotation. rotation only limited by the disc.

significance of postive prone stability test: therapist applies posterior to anterior force then sees if leg and lumbar extension relieves this pain.

extensors will stiffen the spine and resist the PAS force (anterior shear) by exerting a posterior shear force If it decreases the symptoms, the persons pain is likely due to excessive anterior shear forces bc anterior shear forces reproduce the pain and is relieved by posterior shear.

erector spinae muscles -contraction in flexion forward -contraction in extension to upright: in which direction are they capable of producing force? describe the implication of these forces of the vertebral column

flexion = eccentric, extension = concentric They produce extension forces but also compression and posterior shear due to their oblique arrangement posterior shear forces: counteract anterior shear forces of the upper vertebrae that occur in flexion or lifting compressive forces (along w/ contraction of the abdominal muscles) will inc lumbar spine stiffness and stability

Lumbosacral angle

formed by intersection of lines btwn long axis of 5th lumbar vertebrae and the sacrum -greater in males Dependent on sacral inclination (inversely related) -increase sacral inclination -decrease lumbosacral angle -inc lumbar lordosis

Anterior (ventral) Sacroiliac ligaments -location: -superior vs inferior fibers: -resists:

formed by thickening of the anterior SI joint capsule (horizontal at top of pelvis) -superior fibers are thinner and reinforced by iliolumbar ligament above it. -inferior fibers are more developed -resists seperation and horizontal movement of the pelvic bones

lumbopelvic rhythm: flexion

hamstrings eccentrically contract beginning phase: mostly lumbar motion (flexion); - in upper segments then middle then lower middle phase: Both lumbar and pelvic motion; -flex lumbar spine, pelvis tilts anteriorly end phase: mostly pelvic motion (anterior tilt)

Influence of posture on loads at lumbar spine

holding same weight box while bending over require more extensor muscle activation force to prevent person from falling forward. -COG is more forward -larger flexor MA of body weight -larger MA of box

Intervertebral disc in lateral flexion: -flex to R:

increase compessive forces on R of disc -nucleus will translate to the L

Protruding abdomen affect on lumbar spine

increase in abdominal body weight directly affects the forces on the facet joints; compensation by hyperextension of lumbar spine with anterior pelvic tilt will increase the compressive forces at the facet joints -pelvis tilts anteriorly -increased lumbar lordosis bc of lumbar extension to counteract the flexion moment produced by the abdomen -increasing lumbar lordosis shifts load from intervertebral discs to lumbar facets, creates increased compressive forces at facet joints.

Sacrotuberous ligaments -from _______ to __________ -has attachments w/ 2 muscles: -blends with _________ ligaments -forms ___________ -resists ______________

ischial tuberosity to psis, lower sarcrum and cocyx -has attachements with glut max and biceps femoris -blends with the dorsal SI ligaments -helps for the foramen from the notches -Resist nutation: (sacral nutation with posterior pelvic tilt)

Pubic Symphysis: _______disc reinforced by _________ and ________ movement:

joint at which two pubic bones come together -fibrocartilaginous disc btwn 2 pubic bone -reinforced by superior pubic ligament and arcuate pubic ligaments -minimal movements -any movement of sacrum in SI joint is accompanied by minimal movement of pelvic/innonimate bone at pubic symphysis. EX: nutation: ilium of the pelvis come closer together, ischium moves further apart, causes movement at pubic symphysis (connected by fibrocartilage = secondary cartilaginous joint/synchondrosis)

Lumbar vertebral bodies size: width: height: curvature function

larger (inc as go L1-L5) wider sup and inf margins covered by endplates higher anteriorly then it is posteriorly (gives lordosis) -lordosis to withstand greater compressive forces

Coupled motion of lumbar spine

lateral flexion and rotation -coupled in opposite directions when spine is in neutral flex/ext (r lat flexion coupled w/ L rotation) (coupled in same directions for cervical) -opposite arthrokinematics (compression on contralateral for rotation, but compression on ipsilateral for lateral flexion)

Differences in lumbar curvature: when short sitting (hips and knees flexed, feet on floor) vs long sitting (hips flexed knees extended) when supine with hips/knees extended vs hips/knees flexed (hook lying):

long sitting: dec lumbar lordosis due to tight (short hamstrings) muscles inc lordosis w/ hips and knees extended; esp if short/tight hip flexors (quads)

Combined movements when bending forward to touch toes: lumbar spine: Sacrum: Pelvis Hips:

lumbar spine: flexes Sacrum: nutates Pelvis rotates anteriorly Hips: flex to extent allowed by hamstrings

Lumbar vertebral endplate

made of hyaline and fibrocartilage Btwn the bodies and intervertebral discs in the joint (more adhered to the disc then the vertebrae) -may be injured and cause pain.

Different patterns of lumbopelvic rhtym in flexion

may have limited hip flexion due to hamstring tightness, hip stiffness or hip pain causes limited hip flexion with excessive lumbar flexion may be unable to flex lumbar spine (fusion or stiffness) or may avoid flexing lumbar spine (lbp, lumbar instability, fear of movement): limited lumbar flexion with excessive hip flexion.

Osteokinematic motions of the lumbar spine Most: Next: Least: (1 exception)

mostly flexion and extension (inc going down) -next most is lateral flexion -least rotation - (only exception is more rotation then lat flexion at L5-S1)

Intervertebral disc in Sagital or frontal motion:

nucleus pulposus translates to opposite side of compression -this phenomenomenom does not occur in rotation

SI joint motions

nutation and counter nutation: sacral rotation in a sagittal plane -small: ranges from 1-8 deg with mean of 2-3 -variations in amount due to age, sex, joint surface,assymetries in joint structure, ligamentous integrity, degree of degeneration -excessive motion may occur with injury/disease

Intervertebral disc in backward bend/extension:

posterior roll of the superior vertebrae will increase the compressive forces at the poster aspect of the disc. -Nucleus of the dic will translate more anteriorly and cause expansion of the anterior elements of the disc

rotation to the right: which internal oblique?: which external obliques?

right internal left external

5th Lumbar vertebrae orientation of superior and inferior facets: shape allows it to resist: contributes to ____ angle height is greater:

sagital plane orientation of superior facets like rest of L spine but coronal plane orientaion of inferior facets (face anteriorly and slightly lateral) to articulate with base of sacrum -shape allows it to resist anterior shearing of L5 on sacral base -contributes to lumbosacral angle Vertical height is greater anteriorly then posterior: contibutes to lumbosacral angle

Relationship between pelvic and lumbar motion when sitting tall vs slouched (sitting with shoulders fixed, not moving)

sit tall: anterior pelvic tilt with lumbar extension (more lordosis) (hip flexors w/ lumbar extensors) sit slouched: posterior pelvic tilt with lumbar flexion (more kyphosis) (abdominal muscles and hip extensors) (dif pattern of motion than when person bends forward to touch toes: anterior pelvic tilt with lumbar flexion)