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46 Cards in this Set

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The term used to describe the movement between bones
The term used to describe the movement between the joint surfaces of bones
Closed Kinetic Chain
describes a position where the distal segment is fixed
Open Kinetic Chain
describes a position where the distal segment is free to move
Closed packed Position
unique position within most joints of the body where the articular surfaces are most congruent and the ligaments are maximally taut.
What is the Sliding Filament theory?
Active force is generated as actin filaments slide past the myosin filaments, resulting in contraction of an individual sarcomere.
Loose-packed position
places within most joints of the body where the articular surfaces are least congruent and the ligaments are slackened
Mechanical advantage
ratio of the internal moment arm to the external moment arm
Internal Moment Arm
distance between the axis of rotation and the perpendicular intersection with a muscle force
External Moment Arm
distance between the axis of rotation and the perpendicular intersection with a external force
Agonist muscle
muscle or muscle group that is most directly related to the initiation and execution of a particular movement
a progressive strain of a material when exposed to a constant load over time
relative moment arm length possessed by a particular force
property of a material expressed by a changing stress-strain relationship over time.
Translation (Glide and Slide)
linear motion in which all parts of a rigid body move parallel to and in hte same direction as every other point in the body.
Antagonist muscle
muscle or muscle group that has the action opposite to a particular agonist muscle.
branch of mechanics that describes the effect of forces on the body.
forces on a material that act in opposite but parallel directions
ratio of stress (force) to strain (elongation) within an elastic material
ratio of a tissue's deformed length to its original length
property of a material demonstrated by remaining permanently deformed after removal of a force
interaction of two or more muscles acting in different linear directions, but producing a torque in the same rotatory direction
First Class Lever
the axis is between the opposing forces (RAE). MA can be less than, equal or greater then 1 depending on the location of the axis.
Second Class Lever
the resistance is between the axis and effort arm (ARE). MA is always greater than 1
Third Class Lever
the effort is between the axis and resistance arm (AER). MA is always less than 1
when the sum of the internal and external forces acting on a lever are equal.
In the elastic zone when the strain is removed from the structue what happens to its length?
It returns to normal
Given the following information for a first class lever: R= 5, RA=10, E=2, EA=15. What direction would the system move, clockwise or counter-clockwise if the Resistance force is applied to the left of the axis?
Determine the torques for both forces by multiplying the force times the distance. Which ever one is larger will ditate the motion the lever will move. Since in this case the Resistance is to the left of the axis and has a torque of 50 which is greater then the torque of the Effort which is 30, the lever will move in a counterclockwise direction.
Lever systems utilize what kind of force system?
Since the Resistance and Effort force are applied to the same lever and are parallel to one another.
When concurrent forces are applied to an object, what do they create?
Resultant force
What class of lever system always has a Mechanical Advantage that is greater than 1?
Define Mecahnical Advantage
Measure of the efficiency of the lever ( the relative effectiveness of the effort compared to the resistance).
Define Moment Arm.
Shortest distance b/t the action line and the jt axis and is found by measuring the length of a line drawn perpendicular to the force vector, intersecting the joint axis.
If the moment arm of a constant force increases what happens to the amount of torque that is produced?
It increases
The Translatory force is applied _______________ to the lever system.
The Rotary force is applied ________________ to the lever.
Translatory and Rotary forces are examples of what kind of force system?
Define Center of Gravity
A point within a object where it mass is evenly distrubted.
Where is the center of mass located in an upright human body?
Just anterior to the second sacral vertebraa
Define base of support.
defined as the area between the feet and ground where the centre of pressure can be maintained during stance.
What is Newton's first law.
A body remains at rest or in constant linear velocity except when compelled by an external force to chage its state.
What is Newton's second law.
The linear acceleration of a body is directly proportinal to the force causing it, takes place in the same direction in which the force acts, and isinversely proportional to the mass of the body.
Define Newtow's third law.
For every force there is an equal and opposite directed force
Define Passive length-tension
Ocurrs when the parallel and series elastic components are stretched within a muscle.
Define Active length-tension
The force generated by a muscle in response to a stimulus from the nervous system.
Define Resting (optimal) length
The length that allows the greatest number of cross-bridge attachments and, therefore, the greatest potential active force.