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101 Cards in this Set

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  • Back
What are the functions of the annulus fibrosis?
-contains nucleus
-stabilizes vertebrae
-permits multidirectional mvmt
-absorbs shock
How does the annulus fibrosis affect spine movement?
-proteoglycans and collagen fibers limit deformation of the annulus stabilizing the spine while allowing mvmt
What are the functions of the nucleus pulposus?
-absorb/retain water
-force transmission
-nutrition
-equalizes unit stress to annulus
-permits rocking of vertebral bodies
How does the nucleus pulposus affect spine movement?
-spherical shape allows vertebral bodies to pivot in multiple directions
What comprises the cruciform ligament?
-transverse ligament of atlas
-superior band to occiput
-inferior band to body of axis
What are the functions of the cruciform ligament?
-"sling" which holds the dens in alignment, inferior and superior bands prevent slippage of the sling
What are the consequences to a slack or torn cruciform ligament?
-could lead to wobbly dens and uneven rotation decreasing rotation ROM and increasing joint wear
-could also allow dens to move posterior into spinal canal compressing SC
What is the function of the alar ligaments?
-to limit rotation @ the O/A jt
-maintain dens placement
-limit possible stretching of the cruciform ligament by the dens
What structures limit extension of the spine?
-anterior longitudinal lig
-annulus fibrosis
-facet joints
-anterior musculature
What can occur as a result of anterior longitudinal ligament slack?
anterior slippage of one vertebral body on another which:
-decreases the intervertebral foramen increasing nerve root compression
-increases facet compression decreasing mvmt in all planes
What structures limit flexion of the spine?
-supraspinous lig
-interspinous lig
-ligamentum flava
-posterior longitudinal lig
-annulus fibrosis
-posterior musculature
What is the function of ligamentum flava?
-limit flexion
-prevent capsule pinching
-recoil repositions facet jts
-control rate of facet motion during flexion
Slack of the ligamentum flava can cause what dysfunctions?
-abnormal segmental mvmt
-pinching of the capsule
-bulging into the spinal canal compressing SC (known to occur in cspine during extension)
How does the rib cage affect movement of the spine?
-limits movement in all directions of the t-spine
-lower ribs can limit l-spine sidebending
What are the ligaments stabilizing the spine?
-anterior longitudinal
-posterior longitudinal (tectorial membrane)
-interspinous (C7-L5/S1)
-supraspinous (C7-L4)
-ligamentum flava
-ligamentum nuchae (C7-occiput)
-intertransverse
What facet motions occur with flexion of the spine?
-bilateral upslide in lower c-spine, t-spine, and l-spine
-lower c-spine also slides forward
What facet motions occur with extension of the spine?
-bilateral downslide in all regions
What facet motions comprise sidebending of the spine?
-facets on the side toward the motion slide down
-facets opposite the side of motion slide up
-lower c-spine also has accompanying forward and backward sliding
What arthrokinematic motions occur in the lumbar and thoracic spine during rotation?
-facet towards the direction of rotation gaps
-facet opposite the rotation compresses and acts as a fulcrum
What arthrokinematic motions occur at the O/A joint during rotation?
-condyle towards rotation moves slightly back
-condyle opposite rotation moves slightly foward
What arthrokinematic motions occur at the A/A joint during rotation?
-facet towards the rotation moves back
-facet opposite the rotation moves forward
How does spine rotation affect the components of the spinal segment?
-nucleus compression increases
-annulus sheared
-facet opposite rotation compressed
-facet toward rotation gapped
-joint capsule toward rotation stretched
What direction does the SI joint move in primarily and how far does it move?
-anteroposterior
-approx 1-3 degrees (F>M avg)
-rotation and translation occur
What is nutation of the SI joint?
-sacral movement in relation to the ilium as occurs in squatting and forward bending of the trunk
What is torsion of the SI joint?
-movement of the ilium in relation to the sacrum as occurs in supine DKC
When are the loads at the A/O joint lowest?
-full extension
When are the loads at C7-T1 the least? The greatest?
-head directly foward with the chin tucked < head extended < head fully flexed
What muscular actions produce forward flexion of the spine?
-abs and iliopsoas initiate flexion
-gravity takes over
-erector spinae eccentrically control flexion until 60 deg
-at 60 deg, ant pelvic rotation occurs controlled by glut max and hamstrings
What muscular actions produce extension of the spine from a foward bent position?
-erector spinae stabilize spine in full flexion
-glut max and hamstrings post rotate the pelvis 30 deg
-erector spinae concentrically complete extension for last 60 deg
What muscular actions produce sidebending of the spine?
-QL, erector spinae and abs on same side initiate SB, then gravity takes over
-QL, erector spinae and abs on opposite side control SB eccentrically
Which muscles extend, sidebend and rotate the vertebrae to the same side?
-splenius cervicis
-iliocostalis
-longissimus
Which muscles extend and rotate to the opposite side?
-semispinalis cervicis
-multifidi
-trapezius
What active and passive forces resist the line of gravity in the cervical spine?
passive = anterior longitudinal lig
active = none
EXT moment
What active and passive forces resist the line of gravity in the thoracic spine?
passive = post longitudinal lig, lig flavum, supraspinous lig,
active = back extensors
FL moment
What active and passive forces resist the line of gravity in the lumbar spine?
passive = anterior longitudinal lig
active = none
EXT moment
What active and passive forces resist the line of gravity at the A/O joint?
passive = lig nuchae, tectorial membrane
active = posterior neck muscles
FL moment
What active and passive forces resist the line of gravity at the SI joint?
passive = sacrospinous lig, sacrotuberous lig, sacroiliac lig
FL moment
What occurs at the TMJ during stage 1 of jaw opening?
-ant rotation of mandibular condyle in fossa/on disk
-disc stays in place
-sup and inf lamina relaxed
-11 to 25mm b/n incisors
What occurs at the TMJ during stage 2 of jaw opening?
-ant rotation and translation of mandibular condyle over articular eminence
-disc translates anteriorly
-sup lamina stretch, inf lamina tightens
-40 to 50 mm b/n incisors
What occurs during stage 1 of jaw closing at the TMJ?
-post rotation and translation of the condyle back into fossa
-post translation of disc
-sup lamina recoils pulling disc
-inf lamina slackens
-lat pterygoid controls the rate of disc mvmt posteriorly
What occurs during stage 2 of jaw closing at the TMJ?
-post rotation of the condyle in the fossa and on the disc
-disc in fossa
-sup and inf lamina relaxed
What's the difference between the elastic and plastic regions of a stress/strain curve?
-elastic tissue or region will return to its original position after load is removed
-forces that strain a tissue into its plastic region cause a permanent deformation
What is Young's Modulus?
- E = stress/strain
-high Young's modulus indicates high force (stress) with little strain
-low Young's modulus shows high strain (deformation) with little stress
What does Young's Modulus indicate about the elasticity of a tissue?
-HIGH Young's is little deformation with high forces, meaning the tissue is STIFF
-LOW Young's is lots of deformation with low forces indicating the tissue is ELASTIC
What is Resilience of a tissue?
- R = (W - changeW)/W
-it is the mechanical work lost during deformation indicated by the area between the stress/strain curves
What is Damping?
-the opposite of resilience
- D = 1 - R
- good damping materials are not elastic
What is Toughness?
- resistance to mechanical failure (amt of energy absorbed by a material before it breaks)
- energy absorbed is the area under the stress/strain curve
-strength and toughness are NOT equal
What is Fragility?
-opposite of toughness
-material absorbs very little energy before it fails
What is Brittleness?
-very little strain occurs before failure
-materials can be strong and brittle or weak and brittle
What is tissue strength?
-the amount of stress required to cause tissue failure
What is Ductility?
-progressive deformation in tension without failure
-old bone vs young bone: young bone more ductile b/c it deforms farther with tension than old bone
Where is Type I Collagen found and what are it's functions?
-found in: skin, bone, tendon, ligament, fibrocartilage and fascia
-resists tension and stretching
Where is Type II Collagen found and what are it's functions?
-found in: hyaline cartilage and elastic cartilage
-resists pressure
Where is Type III Collagen found and what are it's functions?
-found in: connective tissue of organs, BVs, nerves and muscles
-support structure and important for WOUND closure
What are the functional benefits of Loose CT, Dense Irregular CT, and Dense Regular CT?
LOOSE = permits MOVEMENT
DENSE IRREG = MULTIDIRECTIONAL tension resistance and shear force, protection
DENSE REG = transmits UNIDIRECTIONAL tension force
How do Glycoaminoglycans aid in resisting forces?
-with compression negatively charged GAGs are approximated and repel eachother
-tension forces result in tissue compression so GAGs also help collagen resist tension
Differentiate between the toe, elastic, and progressive failure regions of the Tendon/Lig stress strain curve.
TOE = SLACK out of collagen
ELASTIC = collagen TIGHTENS, 1:1 stress/strain ratio
PROG FAILURE = fibers BREAK, small stress = large strain
How does rate of applied tension affect the tendon/ligament response?
SLOW RATE: low stress = high degree of deformation
HIGH RATE: high stress = much less elongation
What are the functional implications of applying high and low rate stresses to tendons/ligaments?
LOW RATE = good for stretching, would not allow optimal muscle action and mvmt
HIGH RATE = rapid mvmt required, so less mvmt of the tendon results in faster mvmt of the segment
How do tendons/ligaments respond to tension?
tension STIMULATES COLLAGEN production and CROSSLINK FORMATION, which strengthens tendon/ligament
How does the stress/strain curve relate to tendon/ligament injury?
-inc tension = inc microfailure
-inc microfailure to yield pt = permanent deformation and INSTABILITY
-pain and inflammation occur with microfailure
What's the difference between Creep and Load Relaxation?
CREEP = inc strain with constant load
LOAD RELAXATION = dec stress with constant strain (no change in tissue length)
What property allows Creep and Load Relaxation?
-GAGs and collagen reorganize in the tissue over time, allowing either inc strain or dec stress
How does tension benefit the repair of tendons/ligaments?
-collagen production
-large collagen bundle production
-controls fiber alignment
-inc scar strength
-inc rate of healing and completeness of healing
When is the most effective time to apply tension during the process of tendon/ligament repair?
-Fibroplasia stage (5-21 days) and early Consolidation (just after 21 days) when collagen is being produced and remodelled
How does ligament replacement differ from tendon/ligament repair?
-application of tension to the structure must be delayed due to initial degradation of the structure over several weeks
How does immobilization affect joint and surrounding tissues?
-loss of strength and stiffness
-NO INFLAMM = 7 weeks no effect on ligs/capsule
-INFLAMM = adhesions w/in 4 weeks
What are the effects of aging on the mechanical properties of tendons/ligaments?
- 70> = only 5-10% dec
- >70 = 20% dec in tensile strength (weaken), 10% dec in elongation (shorten)
-affect ligs>tendons
How are tension and compression resisted in articular cartilage?
COMPRESSION = GAGs
TENSION = TYPE II COLLAGEN FIBER
(also resists shear)
What are the functions of proteoglycans in articular cartilage?
-resist compression
-aid nutrition
How does cartilage receive its nutrition?
-avascular, so depends on compression-relaxation
-compression removes H2O and waste, relaxation and GAGs bring H2O and nutrients back in
-complete ROM required to feed ALL chondrocytes
Why does the articular cartilage tension stress/strain curve lack a plastic region and what does this imply about its failure in comparison to tendons/ligs?
-less dense and smaller type II collagen compared to type I of tendon/lig
-more proteoglycans and H2O
=> failure without yield point and plastic region
How does creep occur in articular cartilage?
-CONSTANT LOAD compresses H2O and waste out, collagen and GAGs reorganize and further decrease the thickness of the cartilage
How does stress relaxation occur in articular cartilage?
-the thickness of the cartilage remains constant with stress focused superficially
-over time, collagen and GAGs realign to even the stress throughout the cartilage
What are the 3 types of Synovial Joint lubrication?
-BOUNDARY: last ditch, lubricant forced out of surface layer
-HYDRODYNAMIC: jt surfaces not parallel, fluid drawn b/n with mvmt
-SQUEEZE FILM: parallel, fluid squeezed out of concavity w/ compression
What are the types of articular cartilage wear?
INTERFACIAL:
-adhesive: sticky surfaces, mvmt tears surface
-abrasive: particles pressed into surface w/ mvmt
FATIGUE: age/sport
IMPACT: very high rapid forces
What are the steps of articular cartilage degeneration?
-fibrillation
-cavitation
-vertical splitting
-continued erosion
What are the effects of aging on articular and fibrocartilage?
ARTICULAR - by 40, noticeable dec in tension/compression, greater after 50
FIBROCARTILAGE - tension/torsion dec slight by 40, continue after 40
What resists tension and compression in bone?
tension - type I collagen and ground substance of the matrix in herringbone patter
compression - inorganic salts
What are the reasons for remodeling bone throughout the life span?
-microfx repair
-replenish osteocytes
-adapt to stresses
-make Ca2+ available to body
-bony callus remodelling during fx healing
How does bone remodeling occur during growth?
-cylindrical: osteoblasts deposit in subperiosteal, osteoclasts reabsorb in subendosteal
-conical: osteoblasts deposit in subendosteal, osteoclasts reabsorb subperiosteal
How does internal bone remodeling occur?
-old lamellar bone removed in cavity called cutting cone
-cutting cone contains BVs and CT, and cells giving rise to osteoblasts
-becomes closing cone as osteoblasts lay down bone on cone wall
What are the differences in spongy and compact bone and how do they effect bone strength?
-SPONGY is NETWORK of spiny processes at the ends of long bones, WEAKER
-COMPACT is SOLID with osteon columns in shafts of long bones, STRONGER
How does a large cross sectional area of bone affect its mechanical properties?
-more resistant to compression, bending, and torsion
-weaker in tension b/c of hollow structure
-deform less than spongy bone
How does a small cross sectional area of bone affect its mechanical properties?
-weaker in compression, bending and torsion, stronger in tension than bones with larger xsection area
How does aging affect the general properties of bone?
-max strength 20-29yo, gradual decrease after 30
-after 50, trabecular bone strength and amt decrease more rapidly in females
How does aging affect long bones?
-TENSILE and BENDING decrease 25% after 50 yo
-COMPRESSION and TORSION decrease only 15% after 50
How does aging affect vertebral bodies?
-tensile forces of bodies dec 20%
-compression resistance dec 40-50%
-torsion resistance dec 40%
What comprises each of the regions of the myofilament: A-band, H-zone, M-ling, I-band, and Z disc?
A-band: actin and myosin overlap, crossbridges formed
H-zone: myosin only
M-line: myosin filaments overlap
I-band: contain only actin
Z disc: actin overlaps
What adaptations can occur within a muscle cell in response to condition changes?
atrophy - loss of myofibril
hypertrophy - gain of myofibril
length inc - increase # of sarcomeres at ends of muscle
How does muscle fiber arrangement affect force production and displacement?
Parallel: all of force is in line with tendon, fiber contraction equals tendon displacement
Pennate: some force is not directed in line with pull and direction results in less tendon displacement; MORE Muscle fibers = inc total force
What are the three elements of Maxwell's model?
1) A&M the contractile unit
2) series elastic component is tendon
3) parallel elastic component is the CT of the muscle
How does Maxwell's model explain the events of muscle contraction?
1)A&M first tighten the series and parallel elastics
2)movement then begins
3)passive prestretch causes initial contraction to result in movement
4)elastic components return muscle to resting length
According to the Muscle Tension-Elongation curve, which muscles are difficult to stretch and which are easier?
Difficult: sartorius, SCOM
Easier: pec major, gastroc, rec fem
What explains the difference in stretchability between different muscles?
-resistance to elongation produces muscle tension
-rapid rise in tension (SCOM, sartorius) = hard to stretch
-gradual increase in tension (pec major, gastroc) = easier to stretch
How does the temperature of muscle affect its function?
-increased temperature allows inc enzyme activity and crossbridge formation = MORE FORCE
-does not affect ability to stretch muscle
How does aging affect muscles?
-muscles grow to peak size and strength in 20s
-after 30-40 yo decrease in: fiber number, isometric strength and contraction velocity
How can nerve fibers in a peripheral nerve be damaged when tension is applied?
-physical damage from the compression, tensile and shear stress/strain
-inc hydrostatic pressure
-BV may become stretched, dec blood flow to nerve
How can nerve fibers be damaged by compression?
-circumferential = surface dmg, like a BP cuff
-lateral = "edge effect" area under compression is damaged
like a sandwich
Why is nerve regeneration so unsuccessful in a mixed nerve?
-schwann cell availability to form tunnels (all nerves)
-motor and sensory nerves have difficulty finding like nerves
How do you determine the prognosis of a nerve injury?
low force + short duration = good
high force + short duration = fair
low force + long duration = fair
high force + long duration = poor