<ul><li>What movement (or what position) is occurring in the right knee?  </li></ul>
<ul><li>What surface term can be used to describe what you can see of the hand in this photo? </li></ul>
<ul><li>When performing the movement in the picture the head has moved: </li></ul><ul><li>A.) Anterior </li></ul><ul><li>B...
Kinetics Study of Forces Associated with Movement
Scalar Quantities <ul><li>Can be measured by an instrument of scale; they are static (no direction).  Has magnitude only. ...
Vector Quantities <ul><li>Indicate movement; can be measured only at a specific point in time as it is constantly changing...
Tug of War 500 N 200 N 100 N 400 N 300 N
Factors to Describe Vectors <ul><li>Magnitude </li></ul><ul><li>Direction- </li></ul><ul><ul><ul><li>Vertical=Y </li></ul>...
Types of Motion <ul><li>Translation or  Linear  - object moves in a straight line - all points of the object move in the s...
Resolution of Forces <ul><li>May have two forces acting in different directions in the same plane - can determine force by...
Resolution of Forces: Clinical Application 3 N 4 N
Lever System <ul><li>Lever - rigid bar or structure that turns around a fixed point; representing the bones of the body </...
Lever Arms <ul><li>Force - labeled  F </li></ul><ul><li>Resistance - labeled  R </li></ul><ul><li>Force Arm - distance bet...
Torque <ul><li>Torque considered a rotary equivalent to a force </li></ul><ul><li>Produced by levers - moves around a fixe...
First Class Lever <ul><li>Fulcrum is between the force and the resistance (e.g. see saw) </li></ul><ul><ul><li>Example is ...
First Class Lever F R RA FA
1 st  Class Lever
1 st  Class  Leverhttp://video.google.com/videoplay?docid=-1013712987391348587&ei=y0KUSuyeM5qIqQLfvsy7Dg&q=atlanto+occipit...
Second Class Lever <ul><li>Force and resistance are on the same side of the fulcrum with the  resistance between the fulcr...
Second Class Lever F R RA FA
2 nd  Class Lever
2 nd  Class Lever
Third Class Lever <ul><li>Force and resistance are on the same side of the fulcrum with the  force between the fulcrum and...
Third Class Lever F R RA FA
3 rd  Class Lever
Match <ul><li>1 st  class lever </li></ul><ul><li>2 nd  class lever </li></ul><ul><li>3 rd  class lever </li></ul><ul><li>...
Mechanical Advantage <ul><li>Efficiency of a lever - efficient when a small force required to overcome a large resistance....
Mechanical Advantage <ul><li>If mechanical advantage is greater than one, then lever was built for force </li></ul><ul><li...
Law of the Lever <ul><li>Lever is in equilibrium and will not move if:  F x FA = R x RA </li></ul>
What class lever is this?  What downward  force must be exerted at F to balance the downward torques of R1 and R2? 1' 2' 9...
What class lever is this?  What downward  force must be exerted at F to balance the downward torques of R1 and R2?  1' 2' ...
What class lever is this?  What upward  force must be exerted at F to balance the downward torque of R?  What is the mecha...
What class lever is this?  What upward  force must be exerted at F to balance the downward torque of R? What is the mechan...
What class lever is this?  What upward  force must be exerted at F to balance the downward torque of R?  What is the mecha...
What class lever is this?  What upward  force must be exerted at F to balance the downward torque of R?  What is the mecha...
Two Types of Musculoskeletal Torque <ul><li>External  </li></ul><ul><ul><li>Forces outside the body </li></ul></ul><ul><li...
Types of Musculoskeletal Torque
Moment Arm <ul><li>Is the radius of the specific arc of motion. </li></ul><ul><li>This line runs perpendicular from the li...
Changing Resistance Arms
External Torque (Barbell)
External Torque <ul><li>IF </li></ul><ul><li>Sin A = a/c </li></ul><ul><li>Sin 30 degrees = a/.3m </li></ul><ul><li>Find A...
External Torque <ul><li>Here it is! </li></ul>
Internal Torque (Biceps)
Internal Torque
Moment Arm
Internal and external Torque <ul><li>External torque will change throughout the range of motion as the length of the momen...
Muscle Contraction <ul><li>Defined - development of tension in the muscle </li></ul>
Contraction versus Contracture <ul><li>A contraction is an action of the muscle </li></ul><ul><li>A contracture is a patho...
Isometric Contraction <ul><li>Development of tension in the muscle, however, no movement; Length of the muscle does not ch...
Isotonic Contraction <ul><li>Length of the muscle changes </li></ul><ul><li>There is joint movement </li></ul>
Types of Isotonic Contractions <ul><li>Concentric - is a shortening contraction; Length of the muscle shortens; Force is g...
Concentric Contraction
Eccentric Contraction
Forces on Musculoskeletal System
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Kinetics 2009 Lecture 2with Torque Joke Not To Post

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  • Forces are vector quantities - have direction and magnitude Physical Movement - velocity, acceleration, deceleration Weight (both mass and pull of gravity) - pounds, Newtons Force - pounds, Newtons Stress - pascal Friction - Work Arrows indicate vectors - #’s usually accompany vectors showing amount of force. Vectors can be added or subtracted if working in the same line Rugby scrum – Five Guys pushing – 70/60/30/40/50 against four guys 100/75/75/75 250 against 325 - four guys win
  • Magnitude – length of vector indicates “size” Direction – which way it is acting Sense – is it positive (muscle) or negative (resistance) Point of Application – Where it is acting
  • Example: Movement of arms, legs is rotatory A B
  • Example: Draw rectangle on board 3 by 4 with internal line 5 3 N 4 N 5 N
  • Demonstrate with levers
  • Torque is an expression of effectiveness of a force in turning a lever system. Such as opening a car door Using a lever to lift something - longer the force arm less force needed – demonstrate with levers (Aristotle moving the Earth) Clinical application - passive stretching - demonstrate with elbow extension points at wrist and midway to elbow
  • Demonstrate with lever and fulcrum. In balance - forces and force arms equal Or in other words if equal weight on each side Think of a see saw -can adjust length of arms
  • Demonstrate - have fulcrum at one end, resistance in middle and use “fish scale” to show force used Brachioradialis origin – proximal 2/3 of the lateral supracondylar ridge of the humerus and lateral intermuscular septum Inserts - lateral side of the base of the styloid process of the radius
  • Demonstrate again with the force applied in the middle of the lever. Is more force required if the lever is longer and the resistance further away?
  • Demonstrate with different lengths of the force arms and resistance arms, to maintain equilibrium. Do calculations - see examples from past. Go back to type of levers 1 st class show amount of force with one pound on one end 2 nd class – resistance is closer to the fulcrum RA – 1ft. FA – 2ft. Resistance is 1# RA x R = FA x F 1 x 1 = 2 x (answer is .5 #) 3 rd class – force closer to fulcrum R equal 1# RA - 2 ft. FA – 1ft RA x R = FA x F 2 x 1 = 1 x (answer is 2#)
  • Demonstrate with lever and fulcrum - 1 st class lever (R1A x R1) + (R2A x R2) = FA x F (9 x 1) + (3 x 1) = 3 x (answer or Y) 12 = 3 x (Y) or answer is 4 #
  • Demonstrate with lever and fulcrum 1 st class lever (R1A x R1) + (R2A x R2) = FA x F (5 x 1) + (3 x 1) = 4 x (answer or F) 8 = 4 x (F) or answer is 2 #
  • Second class lever – (RA x R) = FA x F (9 x 6) = 18 x (answer or F) 54 = 18 x (F) or answer is 3 # MA = FA/RA MA = 18/9 or 2
  • Second class lever – (RA x R) = FA x F (5 x 3) = 5 x (answer or F) 15 = 5 x (Y) or answer is 3 # MA = FA/RA MA = 5/3 or 1.67
  • Third class lever – (RA x R) = FA x F (10 x 5) = 5 x (answer or F) 50 = 5 x (F) or answer is 10# MA = FA/RA MA = 5/10 or 0.5
  • Third class lever – (RA x R) = FA x F (6 x 2) = 2 x (answer or F) 12 = 2 x (F) or answer is 6 # MA = FA/RA MA = 2/4 or 0.5
  • Example in Brunnstrom - page 36 torque changes for external force – Example is Brunnstrom page 36 picture lifting weight - moment arm is essentially the resistance arm closer to the body less force a person is lifting. -- Overhead # 2 Moment Arm - exists for a moment - Overhead # 3 Example page 62 for internal force or force of muscle - Overhead # 4 Page 73 and 77 of Roberts
  • Kinetics 2009 Lecture 2with Torque Joke Not To Post

    1. 1. <ul><li>What movement (or what position) is occurring in the right knee? </li></ul>
    2. 2. <ul><li>What surface term can be used to describe what you can see of the hand in this photo? </li></ul>
    3. 3. <ul><li>When performing the movement in the picture the head has moved: </li></ul><ul><li>A.) Anterior </li></ul><ul><li>B.) Medial </li></ul><ul><li>C.) Posterior </li></ul>
    4. 4. Kinetics Study of Forces Associated with Movement
    5. 5. Scalar Quantities <ul><li>Can be measured by an instrument of scale; they are static (no direction). Has magnitude only. </li></ul><ul><ul><li>Time </li></ul></ul><ul><ul><li>Space </li></ul></ul><ul><ul><li>Mass </li></ul></ul><ul><ul><li>Speed </li></ul></ul><ul><ul><li>Temperature </li></ul></ul>
    6. 6. Vector Quantities <ul><li>Indicate movement; can be measured only at a specific point in time as it is constantly changing </li></ul><ul><ul><li>1) magnitude </li></ul></ul><ul><ul><li>2) direction </li></ul></ul>
    7. 7. Tug of War 500 N 200 N 100 N 400 N 300 N
    8. 8. Factors to Describe Vectors <ul><li>Magnitude </li></ul><ul><li>Direction- </li></ul><ul><ul><ul><li>Vertical=Y </li></ul></ul></ul><ul><ul><ul><li>Horizontal=X </li></ul></ul></ul><ul><li>Sense/Polarity </li></ul><ul><ul><li>Internal force=positive Y </li></ul></ul><ul><ul><li>External force=negative Y </li></ul></ul><ul><li>Point of Application- Where muscle inserts to origin </li></ul>
    9. 9. Types of Motion <ul><li>Translation or Linear - object moves in a straight line - all points of the object move in the same direction at the same speed, distance, and time </li></ul><ul><li>Rotation (Axial, or angular) - One point of the object is fixed and the remainder of the object moves in an arc around a fixed point. </li></ul>
    10. 10. Resolution of Forces <ul><li>May have two forces acting in different directions in the same plane - can determine force by using the Pythagorean theorem. </li></ul><ul><ul><li>a(squared) + b(squared) = c(squared) </li></ul></ul>
    11. 11. Resolution of Forces: Clinical Application 3 N 4 N
    12. 12. Lever System <ul><li>Lever - rigid bar or structure that turns around a fixed point; representing the bones of the body </li></ul><ul><li>Fulcrum – fixed point around which rest of bar moves; representing a joint axis </li></ul><ul><li>Force - usually representative of a muscle </li></ul><ul><li>Resistance - force that must be overcome by a muscle </li></ul>
    13. 13. Lever Arms <ul><li>Force - labeled F </li></ul><ul><li>Resistance - labeled R </li></ul><ul><li>Force Arm - distance between the application of force and the fulcrum - labeled FA </li></ul><ul><li>Resistance Arm - distance between the point of resistance and the fulcrum - labeled RA </li></ul>
    14. 14. Torque <ul><li>Torque considered a rotary equivalent to a force </li></ul><ul><li>Produced by levers - moves around a fixed point - the rotation makes an arc or circle </li></ul><ul><li>Torque = Force x Force Arm or Resistance x Resistance Arm </li></ul><ul><ul><li>measured in newton-meters or foot-pounds </li></ul></ul>
    15. 15. First Class Lever <ul><li>Fulcrum is between the force and the resistance (e.g. see saw) </li></ul><ul><ul><li>Example is atlanto-occipital joint (head and neck) </li></ul></ul><ul><ul><li>Articulation is of the occipital condyles and superior facets of C1 </li></ul></ul>
    16. 16. First Class Lever F R RA FA
    17. 17. 1 st Class Lever
    18. 18. 1 st Class Leverhttp://video.google.com/videoplay?docid=-1013712987391348587&ei=y0KUSuyeM5qIqQLfvsy7Dg&q=atlanto+occipital+joint&hl=en
    19. 19. Second Class Lever <ul><li>Force and resistance are on the same side of the fulcrum with the resistance between the fulcrum and the force (e.g. bottle opener) </li></ul><ul><ul><li>Example is foot (standing on toes) </li></ul></ul>
    20. 20. Second Class Lever F R RA FA
    21. 21. 2 nd Class Lever
    22. 22. 2 nd Class Lever
    23. 23. Third Class Lever <ul><li>Force and resistance are on the same side of the fulcrum with the force between the fulcrum and the resistance (most levers in the body are third class levers). </li></ul>
    24. 24. Third Class Lever F R RA FA
    25. 25. 3 rd Class Lever
    26. 26. Match <ul><li>1 st class lever </li></ul><ul><li>2 nd class lever </li></ul><ul><li>3 rd class lever </li></ul><ul><li>Fulcrum in the middle </li></ul><ul><li>Force in the middle </li></ul><ul><li>Fulcrum in the middle </li></ul>
    27. 27. Mechanical Advantage <ul><li>Efficiency of a lever - efficient when a small force required to overcome a large resistance. </li></ul><ul><ul><li>MA=FA divided by RA </li></ul></ul><ul><ul><li>Force Arm is greater than resistance arm then MA is greater than 1 </li></ul></ul><ul><ul><li>In third class levers, MA is always less than 1 </li></ul></ul>
    28. 28. Mechanical Advantage <ul><li>If mechanical advantage is greater than one, then lever was built for force </li></ul><ul><li>If mechanical advantage is less than one, then lever was built for speed. </li></ul>
    29. 29. Law of the Lever <ul><li>Lever is in equilibrium and will not move if: F x FA = R x RA </li></ul>
    30. 30. What class lever is this? What downward force must be exerted at F to balance the downward torques of R1 and R2? 1' 2' 9 lbs. 1 lbs. 3' R1 F R2
    31. 31. What class lever is this? What downward force must be exerted at F to balance the downward torques of R1 and R2? 1' 2' 5 lbs. 1 lbs. 4' F R1 R2
    32. 32. What class lever is this? What upward force must be exerted at F to balance the downward torque of R? What is the mechanical advantage of this lever? 9' 9' 6 lbs. F R
    33. 33. What class lever is this? What upward force must be exerted at F to balance the downward torque of R? What is the mechanical advantage of this lever? 3' 2' 5 lbs. F R
    34. 34. What class lever is this? What upward force must be exerted at F to balance the downward torque of R? What is the mechanical advantage of this lever? 5' 5' 5 lbs. F R
    35. 35. What class lever is this? What upward force must be exerted at F to balance the downward torque of R? What is the mechanical advantage of this lever? 2' 4' 2 lbs. F R
    36. 36. Two Types of Musculoskeletal Torque <ul><li>External </li></ul><ul><ul><li>Forces outside the body </li></ul></ul><ul><li>Internal </li></ul><ul><ul><li>Produced by muscles, tendons, and other soft tissue in the body </li></ul></ul>
    37. 37. Types of Musculoskeletal Torque
    38. 38. Moment Arm <ul><li>Is the radius of the specific arc of motion. </li></ul><ul><li>This line runs perpendicular from the line of force to the axis of rotation </li></ul><ul><li>The moment arm or torque arm changes as the muscles contract and lengthen </li></ul>
    39. 39. Changing Resistance Arms
    40. 40. External Torque (Barbell)
    41. 41. External Torque <ul><li>IF </li></ul><ul><li>Sin A = a/c </li></ul><ul><li>Sin 30 degrees = a/.3m </li></ul><ul><li>Find A </li></ul><ul><li>Moment Arm = </li></ul>
    42. 42. External Torque <ul><li>Here it is! </li></ul>
    43. 43. Internal Torque (Biceps)
    44. 44. Internal Torque
    45. 45. Moment Arm
    46. 46. Internal and external Torque <ul><li>External torque will change throughout the range of motion as the length of the moment arm changes. </li></ul><ul><li>Internal torque changes throughout the range of motion as the length of the moment arm changes! </li></ul><ul><ul><li>Internal torque usually operates in response to external torque and is affected by those changes. </li></ul></ul>
    47. 47. Muscle Contraction <ul><li>Defined - development of tension in the muscle </li></ul>
    48. 48. Contraction versus Contracture <ul><li>A contraction is an action of the muscle </li></ul><ul><li>A contracture is a pathological process where soft tissue has become physically shorter and restricts movement </li></ul>
    49. 49. Isometric Contraction <ul><li>Development of tension in the muscle, however, no movement; Length of the muscle does not change and there is no movement at a joint </li></ul><ul><li>Also know as a static contraction </li></ul>
    50. 50. Isotonic Contraction <ul><li>Length of the muscle changes </li></ul><ul><li>There is joint movement </li></ul>
    51. 51. Types of Isotonic Contractions <ul><li>Concentric - is a shortening contraction; Length of the muscle shortens; Force is greater than the resistance </li></ul><ul><li>Eccentric - length of the muscle lengthens; Also called a lengthening contraction; Resistance is greater than force </li></ul>
    52. 52. Concentric Contraction
    53. 53. Eccentric Contraction
    54. 54. Forces on Musculoskeletal System

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