LECTURE 1- biomechanical applications to joint structures and fucntions Flashcards
kinematics
what is the Displacement or motion of a segment without regard to forces that cause movement
what type of displacement is translatory
• Linear displacement
• Movement of segment in a straight line
• Rare in human movement
what type of displacement is rotary
• Angular Displacement
• Movement of segment around a fixed axis (COR)
wha tytpe of displacement is general motion
translation + rotation
majority of human movement
what plane and direction is in the coronal (x-axis)
sagittal plane and flexion and extension
what type of axis and direction is in the transverse plane
vertical (y axis)
IR and Er
what type of plane and axis is abduction and abduction
anterposterior (z-axis_
frontal plan
what is displacement per unit of time, regardless of direction
spped
what is displacement per unit of time in a given direction
velocity
what is a force
push or a pull exerted by one object on another
what type of force is an external force
•Pushes or pulls arising from outside the body
what is Forces that act on structures of the body and arise from within the body
internal forces
examples of internal force
muscles
ligaments
tendons
If the segments are unequal in mass, the new COM vector will lie closer to the ____ segment.
heavier
where is the COM found
anterior to S2
where will the base of support lie
between their feet
a wider BOS will ___ stability
a lower COM will ____ stability a
increase 2x
what is static equilibrium
object remains at rest
what is dynamic equilibrium
objects moves at a constant velocity
balanced forces results in ___
equilibrium
unbalanced forces result in ____
acceleration
what law states An object will continue in current motion until a force causes the speed or direction to change
Law of Inertia - Newtons 1st law
When the sum of the forces or torque do not equal 0, then the object must be ____
accelerating.
If there is only ONE force, there cannot be ______
equilibrium
what law states the force of a object is equal to its max times its accelerations
law of accelerations - newtons 2n claw
what force system is Two or more forces work on the same segment in the same line
linear
what force system is Two or more forces work on the same segment from different angles
concurrent
what law states when 2 objects interact, they apply forces to each other of equal magnitude and opposite direction
law of reaction - newtons 3rd law
what is a tensile force
created by opposite pulls on the same
segment/object
a tensile force is ___ to the long axis of the segment
parallel
what type of force is directed away from the joint surface to which it’s applied
joint distraction force
the joint distraction force is ___ to its joint surface
perpendicular
what force is When two body segments are “pushed” together and “touch”
joint reaction force
what type of force is the ankle weight on a ankle in sitting
distraction force
what Forces are perpendicular and directed toward the joint surface
compression force
what type of force is the ankle weight and foot up on leg press
compression force
what is a shear force
The action of the force is parallel
(//) to the contacting surfaces
shear forces are applied in the —- DIRECTION OF MOVMEMTN
same
what is friction force
The action of the force is parallel
(//) to the contacting surfaces
the friction force is applied in the ___ direction of movement
opposite
when is friction force the greatest
right before the movement occurs (then it drops)
isolated force thru COM is
translation
Isolated force NOT through COM
→
rotation and translation
Two equal and opposite forces →
rotation
what is. Two forces equal in magnitude,
opposite in direction, parallel and applied to the same object at different points
force couple
The greater the force or distance between forces the greater the____
torque
T = (F)(MA)
the longer the moment arm then
the greatest the torque ( vise versa)
what is a bending moment
when a third force is added to a force couple
how many points does a bending moment take
3
bending moments is a common cause of what? WHY?
bone fx
Because a force couple implied equal and opposite magnitude, meaning there is no rotation occurring, so the third force being applied breaks the bone
what is a torsional moment
rotations of a segment around its long axis
what is an example of torsional moments
spiral fx
The direction of pull for any muscle is toward the ____
center of the muscle
when does movement occur (in relation to muscles producing force)
when the torque of a muscle is greater than the opposing torque
placing a heavier weight in your hand during a bicep curl with increase or decrease the torque produced by the bicep
increase
T = F x MA
increases F
what is the function of the anatomical pulleys
to make the torque easier
how do pulleys make the same amount of force produce greater torque
by increasing the MA (deflected by bony prominence)
does the pulleys increase or decrease the moment arm
increases
A force is applied ____ to the segment being acted on will have a larger MA
perpendicular
think about your knee at 90 degrees, gravity pulls straight down through the joint vs at knee extension, gravity acts perpendicular to the leg, creating a large MA
which position do your quads have to work harder in? extension, because gravity has largest MA
A force applied at 0° or 180° (parallel) to the segment will have a ____ MA
smaller
what is a. lever
any rigid segment that rotates around a fulcrum
what has to be greater to produce rotations in the lever systems
effector force has to be greater than the resistance force
1st class lever
axis is between the EF and RF
2nd class lever
the RF is in between teh EF and axis so larger effector force
3rd class lever
EF is in between teh axis and RF so RF is bigger
what is a concentric muscle contraction
active shortening
what is a eccentric muscle contraction
active lengthening
whaat is a isometric contraction
no movement but an active muscle contraction
keeping coffe mug still between table and mouth
The angle of application of most muscles is ____
small
what is the difference between between open and closed chain
open chain is where the distal end of segment is free to move
closed chain is where distal end of segment is fixed
