quiz 2: Arthrokinematics and Biomechanics Flashcards
manner in whih bones move in space without regard to the movement of joint surfaces. Ie. shoulder flexion/extension
osteokinematics
joint surface motion
arthrokinematics
new points on each surface come in contact throughout the movement
roll
one point on a surface contacts new points on adjacent surface (linear movement)
glide or slide
same point on each surface remains in contact
spin
quality of what is felt when a joint is moved passively to its end range and a slight pressure is applied
end feel
definite limit -> boney black
hard end feel
firm with slight give at limitation -> tension in joint capsule, ligaments, muscles/tendons
firm end feel
limitation due to soft tissue approximation and compression due to muscle or adipose tissue mass
soft end feel
limitation due to considerable pain; mechanical limitation not felt yet
empty end feel
The (convex or concave) shape of a bone moving on another bone determines the motion at the joint surface
convex-concave rule
If a convex surface moves over a concave surface, the glide is in the _____ direction of the moving body segment or the roll
opposite
If a concave surface moves over a convex surface, the glide is in the _____ direction of the moving body segment or the roll
same
hoe much of the joint surfaces are in contact with each other
joint congruency
joint surfaces have maximum contact; joint is tightly compressed; ligaments and joint capsule are taut.
close-packed or closed-pack position
joint surfaces have minimum contact; parts of joint capsule and ligaments are lax
open-packed or loose-packed position, or resting position
position usually used when testing a joint for stability
close-packed or closed-pack positions
position usually used for joint mobilizations including joint traction or distraction; used for positioning to help relieve pain in joints
open-packed or loose-packed positions, or resting positions
principles of forces and motion as applied to the structure and function of the human body
biomechanics
factors associated with nonmoving systems
statics
factors associated with moving systems
dynamics
an object at rest tends to stay at rest, and an object in motion tends to stay in motion unless acted upon by an outside force
law of inertia
Newton’s 1st Law
amount of acceleration depends on the strength of the force applied to an object
change in an object’s direction depends on the force applied
acceleration is inversely proportional to the mass of the object
law of acceleration
Newton’s 2nd Law
for every action there is an equal and opposite reaction
law of action-reaction
Newton’s 3rd Law
any influence that results in the movement of an object
force
a quantity that describes magnitude and direction
vector
examples: muscle, ligamentous restraint, bony support
internal force
examples: gravity, weight, friction
external force
2 or more forces acting along the same line
linear force
forces that occur in the same plane and in the same or opposite direction
parallel force
2 or more forces applied to the same point but pulling in different directions; resultant force is dependent on angles of pull and magnitude
concurrent forces
2 or more forces acting in equal but opposite directions to facilitate a rotation
force couple
a force that causes rotation about an axis
torque
____ increases as the force applied increases or the distance from the axis increases
_____ = force x distance
torque
the perpendicular distance between the force’s line of pull to the axis of rotation
moment arm
torque that results in compression of joint; occurs at angles < 90 degrees
stabilizing force
greatest at 90 degrees; decreases as stabilization or dislocation force increase
angular force
torque that tends to pull a joint apart or destabilizes it; occurs with angles >90 degrees
dislocation force
a state of equilibrium defined by the orientation of the center of gravity relative to the base of support
stability
equilibrium: can be disturbed or upset only if the COG is elevated
Stable equilibrium
equilibrium: minimal force required to disturb or upset
Unstable equilibrium
equilibrium: COG unchanged when disturbed
Neutral equilibrium
How to improve stability (5):
- Lower COG
- Increase BOS
- Increase Mass
- increase friction
- focus on a stationary object
a simple mechanical device that makes the work of moving a weight or other load easier
levers
levers are composed of these 4 components:
- a rigid bar/ bone called a lever
- a fulcrum, or axis
- a load, or resistance
- a force, effort that produces movement
____ will provide a mechanical advantage either in power or distance (ROM)
levers
axis located between the force and the resistance F - A - R
first-class lever
Resistance is between force and axis: A - R - F
Favors force and power
second-class lever
Force is between axis and resistance: A - F - R
Favors ROM
Third-class lever
