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Musculoskeletal System > 14. The Mechanics of movement > Flashcards

14. The Mechanics of movement Flashcards

1
Q

Defining normal MOVEMENTS of the Joint

A
  • the TYPE of motion
  • translation
  • rotation (e.g. hip)
  • compound (e.g. knee)
  • the PLANE of motion
  • frontal
  • saggital
  • transverse
  • compound (e.g. subtalar)
  • the RANGE of motion

Application to gait:
* hip
* knee
* ankle and foot

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2
Q

Newton’s 1st Law:

A

Every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.

INERTIA

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3
Q

Newton’s 2nd Law:

A

There is a force equal to change in momentum (mass x velocity) per change in time

F = M x A

force= mass x acceleration

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4
Q

Newton’s 3rd Law:

A

For every action (force) there is an EQUAL and OPPOSITE REACTION (by different bodies)

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5
Q

there are 2 types of MOTIONS:

A
  • LINEAR (TRANSLATIONS)
  • ANGULAR (ROTATIONS)
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6
Q

difference between LINEAR (translations) and ANGULAR (Rotations)

A

LINEAR: FORCE
needed to overcome mass (m)

ANGULAR: MOMENT
needed to overcome Moment of Inertia (I)
(moment of inertia depends on distance from centre of rotation)

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7
Q

what is a MOMENT

A

the TURNING EFFECT of a FORCE

Moments act about a point in a clockwise or anticlockwise direction.

The point chosen could be any point on the object, but the pivot - also known as the fulcrum - is usually chosen

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8
Q

an object is in EQUILIBRIUM when there is no..

A

NO ACCELERATION

NO FORCE about the body

Newton’s 1st Law applies

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9
Q

NON-EQUILIBRIUM when..

A

ACCELERATION

RESULTANT force about the body

Newton’s 2nd law applies

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10
Q

in rigid segments identify 3 PROPERTIES:

(modelling a body)

A
  • MASS
  • CENTRE of MASS LOCATION
  • ROTATIONAL INERTIA (I)
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11
Q

in rigid segments identify 3 FORCES:

(modelling a body)

A
  • GRAVITY
  • EXTERNAL FORCES
  • INTERNAL FORCES (muscles & ligaments)
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12
Q

what is TORQUE

A

the measure of the force that can cause an object to rotate about an axis

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13
Q

MOMENTS are generated by a..

A

TORQUE MOTOR

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14
Q

are MUSCLES torque motors

A

no they are LINEAR ACTUATORS

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15
Q

what type of FORCES do MUSCLES produce

A

additional COMPRESSIVE and SHEAR FORCES across the JOINT SURFACES

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16
Q

what are JOINT REACTION FORCES

A

force generated within a joint in response to forces acting on the joint

17
Q

in Joint Reaction Forces, At extreme ends of the Range of Motion, we also need to include anatomical constraints such as:

A

Ligaments,
Bony blockage

18
Q

how do humans walk (like an…)

A

INVERTED PENDULUM
(foot on ground and pivoting above)

starting point: ‘compass gait’

19
Q

how are the energy levels in the INVERTED PENDULUM mechanism

A

POTENTIAL and KINETIC ENERGIES FLUCTUATE (makes walk more efficient)
- EXCHANGE

20
Q

steps of human GAIT - INVERTED PENDULUM

A

Starting point: compass gait

  1. PELVIC ROTATION
    - Centre of MASS path FLATTENS
  2. PELVIC TILT
    - centre of mass further flattens
  3. KNEE FLEXION during STANCE

4&5. FOOT and KNEE MECHANISMS
- help smoothen the path of the centre of mass

  1. REDUCED LATERAL DISPLACEMENT of the PELVIS
    - Otherwise would be moving right/left
    - avoided by means of tibiofemoral angle and hip adduction
21
Q

INVERTED PENDULUM GAIT gives ENERGY SAVING of … in humans

A

70% in humans
- very efficient walkers

(35-50% in most animals/quadrupeds)

22
Q

RUNNING gives how much ENERGY SAVING in humans

A

50%

23
Q

what causes FORCES in humans

A

COORDINATED MUSCLE ACTION

24
Q

what are CENTRAL PATTERN GENERATORS for

A

key for a lot of daily activities like walking
- so don’t need a brain

in SPINE

25
Q

in the GAIT CYCLE when is the 1ST DOUBLE LIMB SUPPORT

A

INITIAL CONTACT

26
Q

in the GAIT CYCLE when is the 2nd DOUBLE LIMB SUPPORT

A

PRESWING

27
Q

what are the 2 PHASES of the GAIT CYCLE

A

STANCE PHASE
SWING PHASE

28
Q

stages in STANCE PHASE of GAIT CYCLE

A
  1. Initial Contact
  2. Loading Response
  3. Mid Stance
  4. Terminal Stance
  5. Preswing
29
Q

stages in the SWING PHASE of the GAIT CYCLE

A
  1. Initial Swing
  2. Mid Swing
  3. Terminal swing
30
Q

in GAIT CYCLE, what is happening in MID STANCE

A

one leg lifted

middle of stance phase

Musculoskeletal System (18 decks)

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