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239 Terms
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What curves of the spine develop first? Why?
An infant is already in kyphosis (thoracic and sacro-coccygeal have this)
\ Then cervical lordosis develops due to infant gaining head control
\ Finally, lumbar lordosis develops when the infant starts to walk
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What curves are accentuated when the trunk is extended?
The cervical and lumbar lordosis curves are accentuated when the trunk is extended
\ The thoracic kyphosis curve is diminished
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What curves are accentuated when the trunk is flexed?
The thoracic kyphosis curve is accentuated when the trunk is flexed
\ The cervical and lumbar lordosis curves are diminished
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When an individual has ideal posture, what is the position of the line of gravity at the major landmarks (mastoid process, cervical lordosis, thoracic kyphosis, hip joint / lumbar lordosis, knee joint, and ankle joint)
* THROUGH the mastoid process * POSTERIOR to the cervical lordosis * ANTERIOR to the thoracic kyphosis * POSTERIOR to the hip joint / lumbar lordosis * ANTERIOR to the knee joint * ANTERIOR to the ankle joint
(also note that the COM is slightly anterior to S2)
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Why is ideal posture important?
We want to accentuate the natural kyphotic and/or lordotic curves of the spine
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What helps with the stability of the trunk? (Not muscular)
What is the angle for the rings of collagen? What is its purpose?
Each ring has fibers at a 65 degree angle from superior horizontal line; then the next layer has fibers still at this 65 degree angle, but just going in opposite direction
\ This creates a very strong reinforced band
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What directions do the rings of collagen resist in compression?
The rings of collagen resist compression in every direction
\ The annulus fibrosus bows out during compression, and the fibers create and equal but opposite force against it to resist compression
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How do compressive forces placed on intervertebral discs change?
Compressive forces of IV discs change as we change positions
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What are the ligaments of the spine / vertebral bodies?
What is the function of the Anterior Longitudinal Ligament?
Resists anterior shearing and extension of the trunk (also some rotation)
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What is the function of the Posterior Longitudinal Ligament?
Resists posterior shearing and flexion of the trunk
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What is the function of the Ligamentum Flavum?
Resists flexion of the trunk
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What is the function of the Intertransverse Ligament?
Resists lateral flexion of the trunk (i.e., right ligament resists left sidebending)
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What is the function of the Supraspinous Ligament?
Resists flexion of the trunk
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What is the function of the Iliolumbar Ligament?
Resists anterior shearing of L5 at the SI joint and also resists lateral flexion of the trunk
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Which vertebra is the axis and what is the orientation of its facets?
Axis is C2
\ Facets are oriented 20 degrees below the horizontal plane (this means they are relatively flat which allows C1 to rotate freely)
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What is the facet orientation of the cervical vertebrae?
45 degrees anterior to the frontal plane
\ This allows for significant movement
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What is the facet joint orientation of the thoracic vertebrae?
15 degrees anterior from the frontal plane
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What is the facet orientation of the lumbar vertebrae?
25 degrees from sagittal plane
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How do we describe motion at the spine? In other words, what facets are we describing the motion of?
We are describing the motion of the inferior facets on the superior vertebra relative to the superior facets on the inferior vertebra
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What are the arthrokinematics of the atlanto-occipital joint for flexion/extension?
Flexion: anterior roll, posterior glide
Extension: posterior roll, anterior glide
(convex on concave)
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What are the arthrokinematics of the atlanto-occipital joint for lateral flexion?
Ipsilateral roll
Contralateral glide
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What are the arthrokinematics of the atlanto-axial joint for flexion/extension?
Flexion: anterior tilt
Extension: posterior tilt
(convex on convex)
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What are the arthrokinematics of the atlanto-axial joint for rotation?
Posterior slide on ipsilateral side
Anterior slide on contralateral side
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What are the athrokinematics for cervical flexion/extension?
Flexion: superior glide
Extension: inferior glide
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What are the arthrokinematics for cervical protraction/retraction?
Protraction: upper c-spine is extended (C2-C3); lower c-spine is flexed
Retraction: upper c-spine is flexed (C2-C3); lower c-spine is extended
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What are the arthrokinematics of cervical rotation?
Posterior slide on ispilateral side
Anterior slide on contralateral side
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What are the arthrokinematics for cervical lateral flexion (or sidebending)?
Inferior slide on ipsilateral side
Superior slide on contralateral slide
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What is the normal ROM of cervical flexion/extension?
Flexion: 45-50 degrees
Extension: 80 degrees (combined motion)
\ About 20-25 degrees of flexion/extension occurs at the AO and AA joints
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What is the typical ROM for cervical rotation?
About 65-75 degrees of rotation
\ About 30-40 degrees occurs at AA joint
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What is the typical ROM for cervical sidebending?
45 degrees on either side
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What is the closed pack position of the cervical vertebrae?
Extension
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What is the disc height : vertebral body height ration for the cervical, thoracic, and lumbar spines? What does this mean?
Cervical = 2:5 (disc height is \~40% of VB height)
Thoracic = 1:5 (disc height is \~ 20% of VB height)
Lumbar = 1:3 (disc height is \~33% of VB height)
\ Greater ratio = Greater mobility
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The thoracic spine is built for…
Vertical forces (based on facets)
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What are the arthrokinematics of thoracic flexion/extension?
Flexion: superior slide
Extension: inferior slide
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What are the arthrokinematics for thoracic rotation?
Inferior slide for ispilateral side
Superior slide for contralateral side
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What are the arthrokinematics for thoracic sidebending?
Inferior slide for ispilateral side
Superior slide for contralateral side
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What is the normal ROM for thoracic flexion/extension?
Flexion: 30-40 degrees
Extension: 20-25 degrees
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What is normal ROM of thoracic rotation?
30-35 degrees (each direction)
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What is the normal ROM for thoracic sidebending?
25-30 degrees (in each direction)
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What are the arthrokinematics for lumbar flexion/extension?
Flexion: superior slide
Extension: inferior slide
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What are the arthrokinematics for lumbar rotation?
Gapping on ipsilateral side
Compression on contralateral side
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What are the arthrokinematics for lumbar sidebending?
Inferior slide on ipsilateral side
Superior slide on contralateral side
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What is the normal ROM for lumbar flexion/extension?
Flexion: 40-50 degrees
Extension: 15-20 degrees
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What is the normal ROM for lumbar rotation?
5-7 degrees (very little)
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What is the normal ROM for lumbar sidebending?
About 20 degrees (either side)
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What occurs with a kyphotic posture? What are the issues associated with it?
Kyphotic posture causes an individual to be leaning forward, and this causes the head to be in a forward position
\ With this position, this increases the moment arm between the weight of the head to the thoracic spine
\ This therefore accentuates forces that are causing the kyphotic posture
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Which plane has the motion motion in all of the vertebral segments?
Sagittal Plane (flexion/extension)
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Which vertebral joint has the greatest amount of rotation?
Atlanto-Axial (C1-C2)
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What is Fryette’s 2nd Law in the Cervical Spine?
* Side-bending and rotation occur to the same direction
* For example; when we side-bend to the right, we have the same facet motion as rotation to the right * This motion is “coupled”; in other words, when you side bend, there is always some rotation in the same direction
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What is Fryette’s 2nd Law in the Thoracic/Lumbar Spine?
When you have a flexed or extended spine:
* Sidebending and rotation occur to the same direction (same as in the cervical spine)
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What is Fryette’s 1st Law?
In a neutral spine (which is very unlikely)…
* Side-bending is opposite to the side of rotation * For example; if we side bend to the right, we will get rotation to the left
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What is Fryette’s 3rd Law?
* Imposing one motion will limit other motions * For example; if we start with extension of the spine, we will limit side-bending and rotation
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What is the normal lumbrosacral angle?
Normal Lumbrosacral Angle: 40 degrees
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What is the relationship between the lumbrosacral angle and shearing forces?
Body weight is causing compression at the L5, S1 joint
\ However, due to the lumbrosacral angle being \~40 degrees, there is also an anterior shearing force (L5 wants to slide forward on S1)
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What prevents L5 from sliding forward?
* Facet joint (since facet joints change to more frontal plane angle, which helps to resists anterior shearing force) * IV discs (help stabilize and resist shearing force) * Iliolumbar ligament (resists force)
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What is the “weak link” of the L5, S1 articulation?
Pars Interarticularis (the area between the inferior and superior articular processes)
\ If there is a fracture of the pars interarticularis, it will allow L5 to slip anteriorly when shearing force is applied (spondylolisthesis)
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What happens to the compressive/shearing forces if an individual has an increases lordotic curve (extension) of the lumbar spine?
More of the weight bearing forces is going to shift towards anterior shearing
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What is the function of the upper trapezius at the cervical spine?
* Extends the c-spine * Sidebends to ipsilateral side * Rotates to contralateral side
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What is the function of the levator scapulae at the cervical spine?
* Extends c-spine * Rotates to ipsilateral side * Side-bends to ipsilateral side
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What muscles are trunk flexors?
* Rectus Abdominis * Linea Alba * External/Internal Obliques * Transverse Abdominis * Psoas Major
What are the two phases of a sit-up exercise and how do they differ?
* Trunk Flexion Phase (“Crunch”) * Lumbar and Thoracic Flexion * Slight posterior tilt of pelvis * Abdominal muscles do majority of movement * Hip Flexion Phase (Full Sit-Up) * Incorporate the hip flexors to finish the motion (iliopsoas, sartorius, rectus femoris, etc.)
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What is the difference between a bent knee and straight knee sit-up?
“Supposedly, the bent knee de-emphasizes the hip flexors and emphasizes abdominal muscles”
\ However, EMG activity is the same whether bent knee or straight knee
\ Therefore, straightening or bending the knee has NO EFFECT on using one of these muscles or the other as we go through a full sit up
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For normal lumbar and hip flexion, which muscles are most active and when?
For. the first 2/3 of the motion, the erector spinae is eccentrically contracting to resist flexion motion
\ Once we get to 2/3 of the motion, EMG activity of the erector spinae decreases, and the rest of the movement is taken over by the hip extensors (hamstrings, gluteus maximus)
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What are the compensations for an individual with limited hip flexion and an individual with limited lumbar flexion?
Limited Hip Flexion: compensates with excessive lumbar motion (almost hump-back bending over)
\ Limited Lumbar Flexion: Compensates with pelvis/hip flexion; this stretches out the extensor muscles (“does this push butt back?”)
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From lumbar and hip flexion to extension, what muscles are primarily active and when?
Just the opposite as from an extended to flexed position
\ So initial third of this movement is mostly caused by hip extensors (gluteus maximus, and hamstrings)
\ Then in the last 2/3 of the motion, the lumbar extensors (erector spinae) are primarily responsible
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What is the relative length and depth of the deep back muscles?
When is hip contact the greatest during walking? When is the force the greatest?
* Contact area is the greatest from about mid-stance to heel-off * Force is the greatest between foot flat and mid-stance (this force can be up to 3x body weight, therefore the large contact area helps to spread out this force)
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What are the two main networks of the trabecular system of the femur? What forces do they deal with? What direction do they run?
* Medial Network: helps to deal with compressive forces * Runs inferiorly from top of head of femur to about lesser trochanter area * Arcuate (Lateral) Network: helps to deal with tensile forces (is technically the principle tensile group) * Runs superior from just below the greater trochanter in the shaft of the femur to the medial aspect of the head of the femur
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What are the other two trabecular groups of the femur? What are their functions?
* Greater Trochanter Group: assists to reinforce the greater trochanter from the pull of the abductor muscles * Runs from top of greater trochanter to inferior portion of greater trochanter * Secondary Compressive Group: helps to assist and reinforce the greater trochanter group * Runs from medial side of bottom of femoral neck to the greater trochanter group
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What is the purpose of the arches in the neck of the femur?
* Designed for weight bearing ground reaction force that has been transmitted up and body weight is transmitted down * The force coming down on the head causes tensile throughout the neck, and we need the medial network to deal with this (mainly the principle tensile group, but also the principle compressive group)
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What forces does body weight and ground reaction force create on the femoral neck and the femoral shaft?
Medially:
* Compressive forces on inferior aspect (medial aspect) of neck of femur * Compressive forces on medial side of shaft of femur
Laterally:
* Tensile forces on superior aspect (lateral aspect) of neck of femur * Tensile forces on lateral side of shaft of femur
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What is the average degrees that the tibia is abducted from the femur?
About 9-11 degrees
\ Essentially just understand that the tibia and femur are not fully aligned
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What is the normal angle of inclination?
125 degrees
\ Angle of inclination is the intersection of a line down the long shaft of the femur and a line drawn through the femoral neck
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What is coxa vara? What might this present as?
Coxa Vara = angle of inclination < 125 degrees
\ May present as short leg; adducted hip to maintain alignment and knee will be in valgus position (knock knee)
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What is coxa valga? What might this present as?
Coxa Valga = angle of inclination > 125 degrees
\ This might present as a lengthened limb; abducted hip to maintain alignment and knees will be in bow-legged position
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As an infant, you are more likely to start with coxa _____. (Why is this?)
More likely to start with coxa valga (due to no weight bearing)
\ Then, as we age/grow the angle of inclination decreases
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What is center-edge angle? Where is it and what is normal?
Center Edge Angle: measure of the amount of contact area for weight bearing
* Determined by angle between a vertical line to center of femoral head and a line that hits the lateral lip of acetabulum * Essentially tells us the coverage of the acetabulum on the femur
\ Normal Angle: \~ 35 degrees
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What are the consequences/effects of a larger center edge angle?
A larger center edge angle means that the individual has more coverage / a deeper acetabulum; therefore technically is more stable joint
\ Tend to see decreases flexion, internal rotation, and loss of abduction
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What are the consequences / effects of a smaller center-edge angle?
Essentially there is less coverage, meaning there is less stability (especially superiorly and in weight-bearing positions)
\ Since there will be a greater force per unit area, this can lead to premature osteoarthritis
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What is the normal anteversion angle? Why is the head of the femur anteverted?
8-15 degrees is normal anteversion
\ Center of mass sits anteriorly, so it needs to be supported
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What is excessive anteversion? What are the consequences of excessive anteversion?
Excessive Anteversion = angle > 15 degrees
\ Consequences:
* greater potential for anterior dislocation * have less external rotation and more internal rotation
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What are the compensations for excessive anteversion?
* Internal rotation to create more “normal” junction between head of femur and acetabulum * This would create an “in-toeing” effect so to compensate for this, there will probably be some lateral tibial torsion to keep feet pointed straight ahead
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What is retroversion? What are the consequences of retroversion?
Angle of Inclination < 8 degrees
\ Consequences:
* greater potential for posterior dislocation * more external rotation and less internal rotation
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What are the compensations for retroversion?
* Naturally, would externally rotate the femur, so this would cause a toe-out position * Tibia then might be internally rotates to keep the feet straight
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What is the function of the illiofemoral ligament?
* Limits extension * Limits external rotation * Lateral part can also limit internal rotation when in an extended position
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What is the function of the pubofemoral ligament?
* Limits extension * Limits abduction * (has some ability to limit external rotation)
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What is the function of the ischiofemoral ligament?
* Limits extension * Limits internal rotation
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What is the function of the ligament of teres?
* Runs from the head of femur into acetabulum * No significant role in stability, but does provide some blood and nerve supply to head of femur
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What is the close-packed position of the hip joint?
* \~20 degrees of extension * Internal rotation * Abduction
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What is the open-packed position of the hip joint?