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112 Cards in this Set
- Front
- Back
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the location of the center of mass (gravity) of the human body in anatomical position
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COG located at sacral promontory, anterior to S2 (PSIS), at 55% of body height
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Mass, position of COG, size of base of support, and vertical projection of COG for a stable object
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Mass=Large
position of COG=low base of support=wide vertical projection of COG=To a point near the center of the BOS |
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Mass, position of COG, size of base of support, and vertical projection of COG for a mobile object
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Mass=small
position of COG=high base of support=small vertical projection of COG=To a point near the boundary of the BOS |
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3 cardinal planes of motion
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Sagital
Frontal Transverse |
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axis for sagital plane
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lateral
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axis for frontal plane
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anterior-posterior
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axis for transverse plane
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longitudinal or vertical
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movements in sagittal plane
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flexion and extension
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movements in frontal plane
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abduction and adduction
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movements in transverse plane
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rotation
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synovial joints definition
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joints that permit relatively free movement between body segments.
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uniaxial joint type and examples
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Ginglymus (Hinge) – interphalangeal joints; elbow
Trochoid (Pivot) – proximal radio-ulnar joint |
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biaxial joint type and examples
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Condyloid – wrist joint
Saddle – carpal-metacarpal joint of the thumb |
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triaxial joint types and examples
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Ball and socket – gleno-humeral joint, hip joint
Planar – facet joints in the spine |
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closed packed definition
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Each synovial joint has a point in its range of motion where:
-its surfaces are maximally congruent -its capsule and ligaments are maximally elongated and taut. -its surfaces are maximally compressed |
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3 ways joint surfaces move
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(1) rolling
(2) gliding (3) spinning |
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why must joints roll and glide
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-If the moving joint surface rolls on its partner without simultaneously gliding, the surfaces would separate (gap or subluxate) in some places and impinge in others. Roll and glide must occur simultaneously to preserve joint integrity
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why do joints roll and glide in the direction they do
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Roll and glide do not occur in the direction they do because of the shape of the joint surfaces. Roll and glide, like all motions, are produced by forces
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Rules of concavity and convexity
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-When the concave surface is fixed and the, convex surface moves on it the convex surface rolls and glides in opposite directions
-When the convex surface is fixed and the concave surface moves on it, the concave surface rolls and glides in the same direction |
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when you add weight to an original mass, the center of gravity moves:
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migrates toward the added mass
Ex: we know the COM is at S2 normally; however a person with very large shoulder musculature from working out would have a center of gravity that is higher than an average person. |
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when you remove weight to an original mass, the center of gravity moves:
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away from the place from which the mass was removed
Ex: In a person with an amputation of one leg, for example, the center of gravity would migrate higher than S2, and laterally, away from the side of the amputation |
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open chain movement definition
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the proximal joint is fixed or stable while the distal joint moves. Reaching to grasp an object in space, or kicking a ball are examples of open chain movements.
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closed chain movement definition
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the distal joint is fixed or stable, and the proximal joint moves. The stance phase of walking involves closed-chain motion, as do rising from a chair, or performing a pull-up.
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Roll and glide of open chain hip ext and flx
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1. Open chain hip flexion – the femur rolls anteriorly and superiorly and glides posteriorly and inferiorly.
2. Open chain hip extension - the femur rolls posteriorly and superiorly and glides anteriorly and inferiorly |
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Roll and glide of open chain hip abd and add
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3. Open chain hip abduction – the femur rolls superiorly and laterally and glides inferiorly and medially,
4. Open chain hip adduction - the femur rolls inferiorly and medially and glides superiorly and laterally |
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Roll and glide Open chain hip internal rotation/external rotation
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during external rotation the head of the femur spins laterally and during internal rotation the head of the femur spins medially.
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Roll and glide open chain knee flx and ext
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1. Open chain knee flexion – the tibial surface rolls and glides posteriorly and (slightly) inferiorly.
2. Open chain knee extension - the tibial surface rolls and glides anteriorly and (slightly) superiorly |
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Roll and glide open chain knee internal and external rotation
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3. Open chain knee internal rotation – the tibial surface spins medially on the femur
4. Open chain knee external rotation - the tibial surface spins laterally on the femur |
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Roll and glide ankle dorsiflexion/plantar flexion
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1. Open chain ankle dorsi-flexion – the talus rolls anteriorly and superiorly and glides posteriorly and inferiorly on the mortise joint formed by the tibia and fibula.
2. Open chain ankle plantar-flexion – the talus rolls posteriorly and inferiorly and glides anteriorly and superiorly on the mortise joint formed by the tibia and fibula. |
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Forces that influence human movement
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Gravity, muscles, wind/water, ligaments, reaction forces, bones, external weights, friction
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Gravity's point of application
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COG of moving part
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gravity's line of application and direction
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vertical and down
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Outside Forces (Including Muscle Forces) point of application
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Muscle's point of attachment to the moving bone
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Outside Forces (Including Muscle Forces) line of application
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follows muscle or tendon fibers local to the joint being analyzed
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Outside Forces (Including Muscle Forces) direction
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toward center of muscle (belly), Points toward the stable (non-moving) part
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moment arm definition
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the length of the perpendicular distance from the line of application of gravity to the joint’s axis (depicted by the “x”)
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Moment of force or torque equations
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M=Fs
F= force s= moment arm M=Ir I= inertia r= angular acceleration |
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2 Moment definitions
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A moment is a turning effect, produced by a force at some distance from an axis of rotation: M=Fs
A MOMENT produces an angular acceleration in an object (like a body part) around an axis of rotation (like a joint axis). M=Ir |
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4 Knee extensors
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Rectus Femoris
Vastus Lateralis Vastus Medialis Vastus Intermedius |
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8 Knee flexors
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Biceps Femoris
Semitendinosus Semimembranosus Gastrocnemius Popliteus Plantaris Gracilis Sartorius |
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5 Knee internal rotators
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Semitendinosus
Semimembranosus Popliteus – Gracilis Sartorius |
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2 Knee external rotators
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Biceps Femoris
Possibly aided by the tensor fascia latae |
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tibiofemoral axis and possible movements
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Lateral axis (femoral condyles)-flx and ext
Longitudinal axis- tibial rotation |
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patellofemoral joint movment
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tracking only
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MCL characteristics
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-Resists Valgus stress (force coming in laterally)
-Limits knee extension -Runs from the medial epicondyle of femur to medial proximal tibia |
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LCL characteristics
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-Resists Varus stress (force coming in medially
-Limits knee extension -Runs from the lateral epicondyle (femur) to the head of the fibula |
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ACL attachments
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Attaches to the depression in front of the intercondyloid eminence of the tibia and passes up, backward, and lateral to attach to the back of the lateral condyle of the femur.
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ACL limits
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-Limits knee extension and rotation
-Limits excessive forward movement of the tibia relative to a stable femur OR -Limits excessive backward movement of the femur on a stable tibia |
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ACL provides _____% of stability to the knee joint
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90%
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PCL attachments
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Connects the posterior intercondylar area of the tibia to the medial condyle of the femur
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PCL limits
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-Limits knee extension and rotation
-Limits excessive backward movement of the tibia relative to a stable femur OR -Limits excessive forward movement of the femur on a stable tibia |
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close packed position of knee
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extended
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3 forces that drive screw-home mechanism
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1. The shape of the medial femoral condyle
2. The passive tension in the anterior cruciate ligament 3. Lateral pull of the quadriceps muscle |
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What muscle "unlocks" the knee?
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popliteus
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what muscles make up the pes anserinus
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-tendons of the sartorius, gracilis and the semitendinosus merge on the anterior medial surface of the tibia below the medial condyle. (the sgt mms)
-provide additional medial stability to knee |
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Q angle definition
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-A measure of the overall line of pull from the quadriceps
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Q angle is angle between what two lines?
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-From the ASIS to the mid-patella – representing the overall line of force by the quadriceps muscle.
-From the tibial tuberosity to the mid-patella, representing the long axis of the patellar tendon |
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Normal Q angle values
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14 deg for males
17 deg for females; |
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What factors oppose the lateral pull of the patella?
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1. Fibers of the VMO
2. The lateral facet of the groove is steeper than the medial – forcing the patella more medial. 3. Medial patello-femoral ligament – especially important in the last 20 degrees of knee extension. |
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End feel definition
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End-feel is the quality of the resistance to movement that the examiner feels when coming to the end point of a particular movement
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Normal end feels
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Capsular
Ligamentous Bony Soft tissue approximation Muscular |
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Pathologic end feels
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Muscle-spasm
Capsular (abnormal) Boggy Internal derangement Empty |
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knee extension normal end feel
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ligamentous
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knee flexion normal end feel
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soft tissue approximation end feel.
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knee rotation normal end feel
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ligamentous
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describe the relationship between the gravity line and the lateral axis of the knee when the person is standing erect"?
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falls in front of the knee, making knee activity unnecessary because we can use ligamentous restraint
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when the tibia is extended on a stable femur it rotates
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externally
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femur rotates ______ during the last few degrees of of knee extension in a closed chain
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medially (internally)
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Rotational Equilibrium characteristics
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-we assume that muscles act to oppose gravity. This is a good assumption most of the time. We express the assumption in the equation for rotational equilibrium:
- the sum of all the moments that act around a joint's axis is equal to zero |
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Rotational equilibrium equation
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Mm=Mg
Therefore: Fgsg =Fmsm (force of gravity x moment arm of gravity) = (force of muscle x moment arm of muscle) |
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isometric muscle action characteristics
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-The opposing moments are exactly equal.
Mm = Mg -In this situation the joint does not move so the muscle's length remains constant; this is isometric muscle action. Example: hold your cup of coffee so it will not spill |
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concentric muscle actions characteristics
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-The muscles produce a moment that exceeds the moment which gravity produces:
Mm > Mg -In this situation the joint moves as the muscle shortens in a concentric action. -Example…pick up your cup of coffee! |
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eccentric muscle actions characteristics
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-The muscle produces a moment that opposes the effect of gravity, but is nevertheless smaller than the moment that gravity produces:
Mm < Mg -In this situation the joint moves in the direction dictated by gravity's moment. While the muscle's activity exerts a force on its attachments, and controls gravity's effect on the joint, the muscle still elongates. Example…slowly place your cup of coffee back on your desk |
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lateral axis of iliofemoral joint
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passing through the center of the femoral head- directly in line with the top of the palpable greater trochanter of the femur.
Motion: flexion/extension |
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longitudinal axis of iliofemoral joint
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this mechanical axis, is an imaginary line passing through the center of the hip and knee joints.
Motion: internal and external rotation |
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anterior posterior axis of iliofemoral joint
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anterior/posterior – passing through the center of the femoral head – at the groin – midpoint of the inguinal line.
Motion: abduction and adduction |
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iliofemoral ligament limits
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-Limits extension
-Lateral Fasciculus limits external rotation |
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Pubofemoral Ligament limits
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Limits abduction and extreme extension
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Ischiofemoral limits
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Limits internal rotation and extension
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iliofemoral joint close packed characteristics
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The majority of the three ligaments' fibers are elongated at the joint‘s close-packed position of combined:
-Full extension (20 degrees past neutral) -Slight Internal Rotation -Abduction |
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normal end feel of hip hip extension, abduction, and adduction
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ligamentous
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normal end feel of hip flexion
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-soft tissue approximation
-In slender individuals there is a ligamentous end feel |
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Hip flexion with simultaneous knee extension normal end feel
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muscular end-feel
limited by length of HS muscles |
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Hip extension with simultaneous knee flexion normal end feel
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muscular end-feel
limited by length of rectus femoris |
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Problems with the hip joint can originate from two problems
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1. Angle of Inclination of the hip joint –
occurs in the frontal plane 2. Angle of torsion/version of the hip joint occurs in transverse plane |
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version definition
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occurs in the transverse plane of the hip joint and concerns twisting of the femoral NECK within the acetabulum
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torsion definition
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occurs as a twist in the FEMUR itself – also in the transverse plane
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Angle of Inclination of the Hip Joint
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-A normal angle of inclination is about 125 degrees.
-Coxa Vara (angles less than 125 degrees) or Coxa Valga (angles greater than 125 degrees) can alter normal hip biomechanics and/or lead to abnormal joint wear and tear or a leg length deformity |
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Anteversion definition
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-an angle of the head and neck of the femur relative to the frontal plane of the body that is greater than 12 degrees.
-This represents a normal femur abnormally positioned in the acetabulum. |
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retroversion definition
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-an angle of the head and neck of the femur relative to the frontal plane that is less than 12 degrees
-This represents a normal femur that is abnormally positioned relative to the acetabulum |
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Antetorsion definition
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an angle of torsion greater than the upper range of "normal" (ie: greater than 15 degrees).
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retrotorsion definition
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an angle less than the lower range of "normal" (ie: less than 8 degrees)
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what hip joint abnormalities cause toe to point in?
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Ante-torsion and retroversion cause the toe to point IN
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what hip joint abnormalities cause toes to point out?
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Anteversion and Retro-torsion cause the toe to point OUT
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Common problems due to aging of hip joint
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Femoral neck hip fractures
intertrochanteric fractures Arthritis or degenerative joint disease |
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femoral neck hip fractures characteristics
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-Serious because blood supply to the femoral head may be decreased.
-May require total hip replacement surgery |
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intertrochanteric fractures characteristics
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-usually easier to repair than femoral neck fractures
-Age (over 60), osteoporosis and a risk of falling from balance loss all contribute to hip fractures. -serious injury in older individuals and extremely hard to rehabilitate. |
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Arthritis or degenerative joint disease characteristics
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characterized by progressive wearing away of the cartilage of the joint. As the protective cartilage is worn away by hip arthritis, bare bone is exposed within the joint
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when might doctors recommend a total hip replacement?
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When NAISIDS, range of motion exercise, assistive devices, rest, and modalities do not alleviate pain and reduce disability, doctors may recommend a total joint replacement
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6 Hip flexors
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1. Iliopsoas
2. Rectus femoris 3. Tensor fascia latae 4. Sartorius 5. Pectineus 6. Anterior fibers of the gluteus medius |
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iliopsoas importance as hip flexor
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-that because the iliopsoas attaches into the lumbar spine, it is the only muscle attaching proximally enough to flex the hip past 90 degrees
-negligible hip flexor in anatomical position |
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5 hip abductors
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1. Gluteus medius
2. Gluteus minimus 3. Upper fibers of the gluteus maximus 4. Sartorius (only after hip is abducted several degrees) 5. Tensor Fascia Latae |
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5 hip adductors
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1. Adductor magnus
2. Adductor longus 3. Adductor gracilis 4. Adductor brevis 5. Pectineus |
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5 hip extensors
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1. Gluteus maximus
2. Biceps femoris 3. Semitendinosus 4. Semimembranosus 5. Posterior and lateral fibers of the gluteus medius |
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4 hip internal rotators
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1. Tensor Fascia Latae
2. Gluteus Minimus 3. Adductor Group 4. Anterior fibers of the gluteus medius |
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7 hip external rotators
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1. Piriformis
2. Gemellus (superior and inferior) 3. Obturator internus and externus 4. Quadratus femoris 5. Posterior portion of the Gluteus Medius 6. Gluteus Maximus 7. Sartorius |
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What moments does gravity’s force produce at the hip in standing in sagittal plane?
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-In normal standing posture, the center of gravity of the mass superincumbent to the hip joint is located so that its line of application passes posterior to the hip joint's lateral axis
-Gravity's force, acting at a distance from the axis of the hip joint, produces a posterior pelvic tilt. In a closed chain, with the femur relatively fixed, a posterior pelvic tilt produces hip extension |
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What controls gravity's hip extensor movement?
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-In this case, we need not use muscles to stabilize the hip joint during normal quiet standing, because an anterior ligament exists with the same line of application.
-When the iliofemoral ligament elongates, like a very tight spring, it develops an elastic force. Although this force is passive, not active like a muscle's force, it is nevertheless directed at its points of attachment on the ilium and femur. The force prevents the attachments from being pulled further apart, that is, it prevents extension -A vector that represents this ligamentous force looks exactly like the one that depicts the force developed in a hip flexor muscle. |
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What moments does gravity’s force produce at the hip in standing in frontal plane?
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-causes non-stance side of pelvis to drop
-countered by hip abductors |
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positive trendelenberg sign definition
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Inability to maintain a level pelvis in unilateral stance
caused by weak hip abductors |
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ways to counter trendelenberg due to weak hip abductors
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-trunk lean towards weak side (stance leg)
-cane on strong side -carrying an external weight on weak side (stance leg) |
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to change an open chain vector to closed chain simply
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switch the arrow and dot
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