Movement: Lecture 2 8/27

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brau2308
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169874
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Movement: Lecture 2 8/27
Updated:
2012-09-09 17:45:12
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human movement
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review of lecture 2 for human movement
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  1. Force=?
    mass x acceleration
  2. When do we infer the existence of forces?
    when we observe masses being accelerated (or distorted)
  3. What are some forces that influence human movement?
    • gravity
    • muscles
    • wind
    • water
    • ligaments
    • reaction forces
    • bones
    • external weights
    • friction
  4. How do we depict forces?
    using vectors
  5. What four characteristics do vectors have?
    • point of application
    • line of application
    • direction
    • magnitude
  6. Where is the point of application of gravity?
    COG
  7. Where is the point of application of outside forces (including muscle forces)?
    muscle's point of attachment to the moving bone
  8. Where is the line of application for gravity?
    vertical
  9. Where is the line of application for outside forces (including mm)?
    follows muscle or tendon fibers local to the joint being analyzed
  10. What is the direction of gravity?
    down
  11. What is the direction of outside forces (mm)?
    toward center of muscle belly
  12. What is the magnitude of gravity and outside forces?
    arbitrary, drawn to scale
  13. What are the rules for vector analysis?
    1.
    name joint at which movement occurs
  14. Rules for vector analysis
    2.
    determine what segment is moving, what segment is stable, and joint where movement takes place
  15. Rules for vector analysis
    3.
    determine plane of movement in which movement occurs, and axis around which joint moves in this plane
  16. Rules for vector analysis
    4.
    draw simple diagram that illustrates body in plane you named. Estimate location of relevant joint axis, and label it on your diagram w/ a "cross." Even if movement takes place in more than one plane, analyze only one plane at a time
  17. rules for vector analysis
    5.
    focus analysis on moving segment, and begin by considering force of gravity
  18. Rules for vector analysis
    6.
    following rules for gravity forces, depict force of gravity as vector. Determine vector's moment arm and determine moment that gravity produces around joint's axis in the plane depicted
  19. Rules for vector analysis
    7.
    consider other forces, especially muscle forces, that act on moving segment
  20. Rules for vector analysis
    8.
    decide which muscle forces act in a direction that produces moments that oppose gravity's moment
  21. Rules for vector analysis
    9.
    follow rules for muscle forces to depict these muscle forces as vectors
  22. Rules for vector analysis
    10.
    determine each muscle vector's moment arm with respect to the joint axis
  23. What terms are synonymous with torque?
    • strength
    • moment of force
  24. Moment:
    • a turning effect, produced by a force at some distance from an axis of rotation [M=Fs]
    • M= moment's magnitude
    • F=force (N or lbs)
    • s=force's moment arm (length-cm/in)
  25. moment arm:
    length of perpendicular distance from line of application of gravity to the joint's axis
  26. Just as a FORCE produces straight line acceleration in a object at rest, a MOMENT produces..
    • an angular acceleration in an object around an axis of rotation [M=Ir]
    • I=moment inertia
    • r=angular acceleration
  27. What is a moment of inertia?
    • rotational equivalent of mass in its mechanical effect, that is, the resistance to a change of state during rotation
    • a mass's moment of inertia depends on how that mass is distributed about an axis of rotation
  28. Kinematics:
    study of direction, extent, and speed of motion
  29. What motions are possible in the lateral axis of the tibio-femoral (knee) joint?
    flexion and extension
  30. What is the close-packed position of the tibio-femoral (knee) joint?
    extension
  31. What motions are possible in the longitudinal axis of the tibio-femoral (knee) joint?
    tibial rotation
  32. What motion is possible at the patello-femoral joint?
    tracking only
  33. What is the function of the medial collateral ligament of the knee?
    • resists valgus stress
    • limits knee extension
  34. Where is the location of the medial collateral ligament of the knee?
    runs from medial epicondyle of the femur to medial proximal tibia
  35. What is the function of the lateral collateral ligament?
    • resists varus stress
    • limits knee extension
  36. Where is the location of the lateral collateral ligament of the knee?
    runs from lateral epicondyle (femur) to the head of the fibula
  37. What is the function of the ACL?
    • provides 90% stability to knee joint
    • limits knee extension and rotation
    • limits excessive forward movement of tibia relative to a stable femur OR
    • limits excessive backward movement of the femur on a stable tibia
  38. Where is the location of the ACL?
    attaches to depression in front of intercondyloid eminence of tibia and passes up, backward, and lateral to attach to back of lateral condyle of femur
  39. What is the function of the PCL?
    • provides additional stability to the knee joint
    • limits knee extension and rotation
    • limits excessive backward movement of tibia relative to stable femur OR
    • limits excessive forward movement of femur on a stable tibia
  40. Where is the location of the PCL?
    connects posterior intercondylar area of tibia to medial condyle of femur
  41. What are menisci?
    cartilaginous structures that are shaped concave superiorly, and continuous w/ tibia inferiorly
  42. Where are the menisci attached?
    medial and lateral attached to small depressions b/w condyles of tibia (intercondyloid fossa)
  43. Are the menisci attached attached in the center?
    no, unattached and their shape narrows to a thin shelf in the center
  44. Arthrokinematics
    During Knee extension:
    Open chain
    • tibia glides anteriorly on femur
    • tibia rotates externally (screw-home mechanism)
  45. Arthrokinematics
    During knee extension
    Closed chain:
    • femur glides posteriorly on tibia
    • femur rotates internally on stable tibia (screw-home mechanism)
  46. Arthrokinematics
    During knee flexion
    Open chain:
    • tibia glides posteriorly on femur
    • tibia rotates internally
  47. Arthrokinematics
    During knee flexion
    Closed chain:
    • femur glides anteriorly on tibia
    • femur rotates externally on stable tibia
  48. What causes these roll and glide knee joint movements?
    shapes of tibial and femoral surfaces DO NOT cause these movements

    tibial glide is produced by muscle forces
  49. During open chain knee extension:
    The tibia rolls-
    • anteriorly
    • quadriceps pull on tibia causes it to glide anteriorly
  50. During open chain knee flexion:
    tibia rolls-
    • posteriorly
    • hamstring's pull on tibia causes it to glide posteriorly
  51. The screw home mechanism is driven by 3 forces:
    • 1. shape of medial femoral condyle
    • 2. passive tension in ACL
    • 3. lateral pull of quadriceps muscle
  52. What unlocks the knee?
    • knee to the knee
    • popliteus
  53. What muscles move the knee?
    • rectus femoris
    • vastus lateralis
    • vastus medialis
    • biceps femoris
    • semitendinosus
    • semimembranosus
    • gastrocnemis
    • popliteus
    • plantaris
    • gracilis
    • sartorius
    • possibly tensor fascia latae
  54. What are the extensors of the knee?
    • rectus femoris
    • vastus lateralis
    • vastus medialis
    • vastus intermedius
  55. What are the knee flexors that cross 2 joints?
    • biceps femoris -long head
    • semitendinosus
    • semimembranosus
    • gastrocnemius
  56. What are the knee flexors that cross 1 joint?
    • biceps femoris -short head
    • popliteus
    • plantaris
    • gracilis
    • sartorius
  57. What are the internal rotators of the tibia w/ respect to the femur?
    • semitendinosus
    • semimembranosus
    • popliteus
    • gracilis
    • sartorius
  58. What are the external rotators of the tibia w/ respect to the femur?
    • biceps femoris
    • possibly tensor fascia latae
  59. Does the patella track only superiorly?
    no, as knee extends, patella pulled in lateral direction because of larger size, direction, and cross-sectional area of vastus lateralis
  60. What is the Q-angle?
    • quadriceps angle
    • a measure of overal line of pull from quadriceps
    • formed in frontal plane by two line segments
  61. What two line segments form the Q-angle?
    • from ASIS to the mid-patella --representing overall line of force by quads
    • from tibial tuberosity to mid-patella, representing long axis of patellar tendon
  62. Increases or decreases in Q-angle are associated w/...
    increased peak patellofemoral contact pressures
  63. What is the normal Q-angle for males?
    14 deg
  64. What is the normal Q-angle for females?
    17 deg
  65. Biomechanics of patellofemoral joint are effected by:
    patellar tendon length and Q-angle
  66. The posterior line of pull of vastus medialis oblique causes the patella to:
    stay securely in intertrochlear groove during its glide superiorly w/ knee extension
  67. What factors oppose lateral pull of patella?
    (What causes patella to track normally?)
    • fibers of vastus medialis oblique
    • lateral facet of groove is steeper than medial--forcing patella more medial
    • medial patello-femoral ligament --esp important in last 20 deg
  68. How do we manage lateral "bowstringing" forces on the patella?
    • increase control by hip abd mm
    • increase control by hip ext rot mm
    • increase control of quads
    • increase control of mm that support arch of foot
    • MODIFY activites that creaste unnecessarily large stress on PF joint...particularly working in large angles of knee flexion
  69. PROM:
    passive movements end-feels
  70. End-feel:
    quality of resistance to movement that examiner feels when coming to the end point of a particular movement
  71. What do end-feels provide the therapist with?
    critical info about what structure is/are limiting motion
  72. Normal end-feels:
    • capsular
    • ligamentous
    • bony
    • soft tissue approximation
    • muscular
  73. Pathologic end-feels:
    • muscle-spasm
    • capular (abnormal)
    • boggy
    • internal derangement
    • empty
  74. At the end of available passive movement into knee extension, further extension is normally limited by 4 ligaments we have discuss, making the normal end-feel...
    ligamentous
  75. At end of available passive movement into knee rotation, further rotation is normally limited by 4 ligs, making normal end-feel...
    ligamentous
  76. At end of available passive movement into knee flexion, further flexion limited by tissue of hamstrings againsts gastroc-soleus mm, making normal end-feel...
    soft tissue

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