kinematics, kinetics, muscle performance and function and joints test questions Flashcards
what are the components of kinematics?
displacement, velocity and acceleration
what is kinematics?
branch of mechanics that describes motion of objects
what is displacement?
change in position of an object
what is velocity?
- Rate at which an object moves in a given direction
- Time rate of change of displacement (m/s)
what is acceleration?
rate of change of velocity with respect to time
what are the two types of motion?
linear (translation) and rotational
what is linear motion?
all points move equidistant in the same direction, at the same time (translation)
- occur in a straight line (rectilinear)
- occur in a curvature (curvilinear) (ex. gait)
what is rotational motion?
circular motion around a fixed point (angular)
- all points rotate simultaneously
- axis or rotation is the pivot point
what is the relationship between linear and rotational motion? what is an example of this?
(1) there is a direct relationship
- most motion involves a combination
(2) glenohumeral joint
what is the difference between osteokinematics and arthokinematics?
osteokinematics: includes ROM, Planes of motion, degrees of freedom
arthrokinematics: describes movement of the joint surfaces when a bone moves through a ROM (includes roll, spin and glide)
what is joint play?
the passive movement in the form of translation
what is the instantaneous center of rotation (ICR)
(1) point about which rotation of an object takes place
- changes throughout the ROM due to the spinning, gliding, and rolling
- the closer the center of rotation is to the joint surface, the more gliding takes place
what is the closed packed position (in general)?
joint position in which the ends of the two surfaces are most congruent. Ligaments are on max tension and joint surfaces can not be separated.
what is the loose (open) packed position?
position in which a joint has its greatest capacity or volume. Joint ends can easily be separated and ligaments are in a position of laxity.
what is kinetics?
the study of motion and the forces that act to produce the motion
define mass (m)
the amount of matter that makes up an object (weight includes gravity)
define center of mass (CoM)
point about which the body’s mass is evenly distributes (whole body or one segment)
define inertia
amount of energy required to alter a body’s velocity
define momentum (p)
quantity of motion of an object and is equal to the mass and the velocity (v) p=mv
define friction
parallel force that opposes or impedes motion between two contacting bodies
what are the different types of forces?
- tensile
- compressive
- shear
- bending
- torsion
- combination
example of internal forces within the body
muscle contraction, muscle, ligament stretch, tendon
example of external forces acting on the body?
gravity and weight
what is torque?
moment force or rotational force
- forces applied at a distance from an axis/joint can produce rotation
what is the moment arm?
the distance the force is applied from the axis of rotation
What is the concave-convex rule?
When a concave surface moves on a convex surface, roll and glide occur in the same direction.
What is the convex on concave rule?
When a convex surface moves on a concave surface, roll and glide occur in the opposite direction.
What is a tensile force?
Cool linear forces acting in opposite directions to pull an object apart.
Ex: ligament tear
What is a shear force?
Complainer and opposite in direction but not collinear. These forces cause 1 surface of a body to slide past an adjacent surface.
Ex: blister
What is a compressive force?
Collinear forces acting in similar directions to push tissues together. Ex: compression fracture, a fall
What is static rotary equilibrium?
When internal and external torque are equal.
What is the law of inertia?
A body at rest will remain at rest unless acted upon by a resultant force.
What is the law of acceleration?
A body subjected to a resultant force will accelerate in the direction of that force, and the magnitude of the acceleration will be proportional to the magnitude of the force.
What is the law of action-reaction?
To every action there is an equal and opposite reaction.
Class 1 lever
FAR
MA > or <1
Ex: Selenus muscle in neck
Class 2 lever
ARF
MA>1
Ex: gastrocnemius/soleus in calf, rising up on toes
Class 3 lever
AFR
MA<1
Ex: biceps curl
Muscle skeletal properties;
Extensibility
The ability to be stretched or to increase in length. Determined by connective tissues, surrounding muscle.
Muscle skeletal properties;
Elasticity
Ability of a tissue to return to its normal resting length after removal of a stretch. Determined by connective tissue about and within the muscle.
Muscle skeletal properties;
Irritability
The ability to respond to stimulation from the nervous system. Muscles are very irritable and respond very quickly.
Isometric
- Static contraction
- no change in muscle length
- advantageous when joint movement is restricted (post surgical brake)
Isotonic
-provides contraction
-change in muscle length occurs
-concentric (shortening)
eccentric (lengthening) greatest force
Isokinetic
- concentric or eccentric
- constant velocity is maintained throughout the muscle action
Strength
Ability of the muscle to exert a max force or torque at a specified determined velocity.
- absolute
- relative
Power
Rate of work per unit time
Power= force x velocity
Endurance
Ability to perform low intensity, repetitive, or sustained activities over a. Prolonged period w/o fatigue
Factors affecting muscle performance
- neural control and adaptation
- muscle fiber arrangement
- muscle length
- Joint angle
- muscle fiber type
- muscle fiber diameter
- force velocity relationship
- training specificity
Clinical measures of muscle performance
- anthropometric (measuring size, weight, properties)
- MMT (tests strength of individual muscles)
- dyamometry (assess pinch and strength)
- isotonic (lifting a fixed max against gravity)
List the types of joint receptors found in diarthrosis synovial joints
- ruffini endings (sensitive to stretch at extremes of joint motion)
- Pacinian corpuscles (detect compression, pressure, movement)
- Golgi tendon (detect pressure and forceful motion at extremes)
- unmyelinated free nerve endings (detect noxious and nonnoxious movements and stress)
