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Movement Systems Final > Week 1 > Flashcards

Week 1 Flashcards

1
Q

DEGREES OF FREEDOM

A

Number of independent directions of movement

Can have up to three degrees of freedom (corresponding to 3 cardinal
planes)

Stability vs mobility

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2
Q

AXIS OF ROTATION

A

Pivot point about which motion is occurring
In what plane does the axis lie?

Importance of knowing the location of axis of rotation

The plane of the axis of rotation is perpendicular to the plane of the osteokinematic
motion

Able to determine muscle actions – Application!!!

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3
Q

Translation

A

surface to surface motion

linear motion

arthokinematics: slide

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4
Q

Rotation

A

circular motion

osteokinematics:
flex/ext = sagittal
ab/adduction = frontal
int/ext rotation = transverse

arthrokinematics:
roll spin

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5
Q

Internal force

A

muscles - active and passive

Can be active (stimulated muscle under volitional control) or passive (generated by tension in stretched periarticular
connective tissues, such as intramuscular fascia, ligaments, joint
capsule)

ligaments and tendons

joint capsules

compression force
tension
shear force

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6
Q

External force

A

COM

Friction

Gravitational force – pulling on mass of body, a body segment,
or an external load

Contact force – push, pull

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7
Q

MechA =

A

IMA/EMA

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8
Q

Kinematics

A

Branch of mechanics that describes:
* Motion of the body (joints) without regard to forces or torques that may
produce motion

2 types of motion
* Translation – Linear motion
* Rotation – Angular motion

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9
Q

Translational/Linear motion

A

Joint surface to surface motion- all parts of a body/segment move parallel to and in the same direction as the other parts of a body/segment (can be in a
straight line or curved path)
* Sliding in knee extension

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10
Q

Rotational/Angular motion

A

Circular motion

Body moves about a pivot point, so all points of the body simultaneously rotate
in the same angular direction

Motion of two adjacent long bones relative to each other

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11
Q

Axis of rotation

A

Pivot point for the angular motion

Center of rotation
* Changing throughout joint movement
* Bones rotate about a joint in a plane that is perpendicular to the axis of rotation

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12
Q

Osteokinematics

A

Motion of bones relative to the 3 cardinal planes of the body (person in
anatomic position)

Movement can occur in 2 different ways
* Proximal segment can rotate against the relatively fixed distal segment (closed chain)
* Distal segment can rotate against the relatively fixed proximal segment (open chain)

  • “Knee flexion” describes “relative motion”;
  • Does not tell you which segment is moving
    -i.e. tibial on femoral or femoral on tibial
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13
Q

open chain

A

proximal segment fixed

distal segment free

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14
Q

closed chain

A

proximal segment free

distal segment fixed

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15
Q

Kinematic chain

A

refers to series of articulated segmented links

i.e. scapula, humerus, ulna/radius, carpals

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16
Q

Closed chain

A

the distal end of the extremity is fixed to the earth or other immobile object

e.g. squat, pull up

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17
Q

Open chain

A

distal end of the extremity is not fixed and is free to move

e.g. knee extension machine, bicep curl

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18
Q

Arthrokinematics

A

Describes motion that occurs between the articular surfaces of the joints

Joint surfaces range from flat to curved

One surface usually relatively convex, one concave

Helps to improve joint congruency, dissipate forces by increasing the
surface area, and guide the motion between bones

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19
Q

3 fundamental arthrokinematic movements:

A

spin
roll
slide/glide

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20
Q

Spin

A

Bone can also rotate by spinning its articular surface against the articular surface
of another bone (radio humeral joint)

21
Q

Roll and glide

A

Rolling convex surface typically involves slide in the opposite direction

Many joints combine rolling and slide with spinning (e.g., femoral on tibial knee
extension the femur spins internally as the femoral condyle rolls and slides on the
relatively fixed tibia)

22
Q

Convex-Concave Rule

A

Direction of arthrokinematics rolling and sliding motion

It depends on which surface is moving

23
Q

Convex moving on Concave

A

Rolling and sliding are in the OPPOSITE direction

24
Q

Concave moving on Convex

A

Rolling and sliding are in the SAME direction

25
Q

Passive tension-

A

helps joint stability and
reduces passive accessory movement

Taut pubofemoral Ligament
From Extension and abduction

Taut ischiofemoral Ligament
From extension and internal rotation

Taut iliofemoral
Ligament from
extension

26
Q

Line of gravity
(LOG)

A

causes
extensor torque,
counterbalanced
by passive flexor
torque of hip
ligaments

27
Q

Close-packed vs. Loose-packed position

A

A joint is most stable at its close-packed position

A joint is most mobile at its loose-packed position

Joint stability can also be achieved by active muscle forces

28
Q

The close-packed position is when

A

Articulating surfaces are maximally congruent

Ligaments or capsule are pulled tight (passive tension)

29
Q

Impact of forces on the MSK system

A

A force that acts on the body is referred to as a load

Forces or loads that fixate or stabilize the body can also deform or injure the body

30
Q

Open chain movement

A

The prime mover is usually muscle force

Decreased co-activation of antagonist muscles

31
Q

Closed chain movement

A

The prime mover is gravity when the body is moving toward the
Earth

The prime mover is when the body is moving away from the
Earth is often defined in terms of muscle groups

Increased co-activation or eccentric activation of antagonist
muscles

Increased loading on the joint

32
Q

Kinetics

A

describes the effect of forces on the body
(force – a push or pull that can start, stop,
or modify movement)

33
Q

Newton’s 1st law of motion

A

(sumF = 0)

A body remains at rest or in constant
linear or angular velocity except when
compelled by an external force to
change its state

Objects in equilibrium….for example, consider a
hockey puck resting on ice; the forces are (=)

After the puck is struck, it is accelerated and will
again be in equilibrium until another force acts on it

34
Q

Newton’s 2nd law of motion

A

quantity of the force is = to the product of the mass that received the
force and the acceleration of the mass

F = ma

the acceleration of a body is proportionate to the magnitude of
the resultant forces (F) on it and inversely proportionate to the mass (m) of the body

35
Q

Unit of force is a

A

(N)

1N= 1kgX 1m/sec2

36
Q

Newton’s third law of motion

A

action and reaction

For every action force there is an = and
opposite reaction force

The state of motion of a body depends on
the forces acting on that body (vs the
forces it may exert on other bodies)

Walking up slippery icy driveway

37
Q

External force: Gravity
(concept of COG)

A

Center of mass – point in every body or object
about which the mass is evenly distributed

Human body COM is just anterior to S2 when standing

Gravity acts on the center of mass of the body
segment or an object

When subjected to gravity, the COM is referred to
as the COG (weight is the effect of the acceleration
of gravity on a mass – (Wt=m*G)

38
Q

Center of mass (COM)

A

During movement, the COM is continually changing

The location being a function of the size and
location of the individual body segments

39
Q

Concept of COG

A

The direction of the external
force due to gravity is
referred to as the line of
gravity (LOG)

40
Q

Forces can stabilize joints and body

A

Newton’s 1st law of motion (sumF = 0)

41
Q

Forces can produce body motion

A

Newton’s 2nd law of motion (sumF = ma)

42
Q

Action and reaction

A

Newton’s 3rd law of motion

Internal and external forces counterbalance each other to:
control body movement (sumF=Fi+Fe=ma)

maintain stability (sumF=Fi+Fe=0)

43
Q

Each force (internal and external) is depicted by an arrow that represents a vector

A

Vector is described by its:
> Magnitude

> Direction (commonly referred to as the line of force and line of
gravity)

> Sense (indicated by arrowhead) depicting whether the force is
acting upward (positive) or downward (negative)

> Point of application of the force

44
Q

Torque

A

rotatory equivalent
of force

Product of the force x perpendicular distance (d) from the line of action to the axis of motion. So, (τorque =F * d)

Forces acting a distance from the axis of rotation will produce rotation at the joint

Moment arm

Torque = Force x moment arm

Force pushes/pulls in a linear fashion, torque rotates an object about an axis

45
Q

Moment arm

A

the shortest distance from the force vector to the axis of rotation

Internal moment arm (IMA)

External moment arm (EMA)

46
Q

Levers

A

Simple machine consisting of a rod suspended across a
pivot point

Converts force into torque

Leverage describes the relative moment arm (MA) possessed by a particular force; the longer the MA, the
greater the leverage

47
Q

Musculoskeletal Levers

A

Internal and external forces produce torques
through a system of bony levers

Internal and external torques counterbalance
each other to produce motion or to achieve
stability of these levers

Motion: sumT = Ti + Te = Iα (angular acceleration)
Newtons second law

Stability: sumT = Ti + Te = 0

48
Q

3 classes of levers

A

1st class levers can have a MechAdv =, <, or > than 1

2nd class levers always have an MechAdv> than 1

3rd class levers always have an MechAdv <1

49
Q

Mechanical advantage

A

(Mech Adv) of msk
lever is defined as the ratio of the Internal
moment arm (IMA) to the length of the
External moment arm (EMA)

Movement Systems Final (11 decks)

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