Lecture 3-Physical Biomechanics I Flashcards
Mechanics
Deals with the analysis of forces acting on an object
The study of forces and their effects
Statics
The study of bodies at rest or at a constant velocity
Dynamics
The study of bodies moving at changing velocities
Kinematics
The study of motion (the Effect)
Kinetics
The study of forces that produce motion (the Cause)
Biomechanics
The application of mechanics to living creatures
Forces
Could be from internal or external sources
What are the most common forces produced by?
Muscle Gravity Inertia Buoyancy Contact forces
What are examples of contact forces?
Ground reaction force Joint reaction force Friction Fluid resistance Air Water Synovial fluid
Application of Biomechanics
ROM measurement
Research
Athletes
Therapeutic Exercise
Center of Gravity
A theoretical point which is the center of mass
A hypothetical point at which all mass would appear to be concentrated, and is the point at which the force of gravity would appear to act
Where is the center of gravity in homogenous objects?
In the middle, equal distant from the ends
Where is the center of gravity in non-homogenous objects?
Skewed towards the greater mass
4/9th rule
Base of support
The area that circumscribes contact with supporting surfaces
Stability
A relationship of the CG to the BOS
Stable when CG lined up over the BOS
What is the degree of stability dependent on?
Location of CG
Area of Base of Support
What is the inverse relationship involved with stability
Increased Height of CG=Decreased stability
Decreased height of CG=increased stability
What is the direct relationship of stability?
Increased BOS=Increased stability
Decreased BOS=decreased stability
What are the mechanisms available for stability?
Sensory mechano-receptors within skin Stretch receptors in muscle Visual system Vestibular apparatus Pressure receptors in skin
What are the stages of motor control?
Mobility
Stability
Controlled mobility
Skill
Why are the stages of motor control used?
To determine the rate of progression of functional tasks the patient will perform and with what degree of assistance/supervision
Where is the CG in the full body?
Just anterior to S1-S2 (Males slightly higher than females
Where is the CG in the head, arms, trunk?
Anterior to T10
Where is the CG in the extremities?
4/9ths rule from proximal end
What is Newton’s Law of inertia?
A body tends to remain at rest or in uniform motion until acted upon by an unbalanced set of forces
What is Newton’s Law of Acceleration?
Acceleration of a body is proportional to the unbalanced set of forces acting upon it and is inversely proportional to the mass of the body
F=ma
What is Newton’s Law of Reaction?
For every action there is an equal and opposite reaction
What is Rotary motion?
Movement about/around an axis
Clockwise +
Counterclockwise -
What is translatory motion?
Movement in a linear fashion with in a plane
What are factors characterizing a force?
Magnitude
Direction
Line of Application
Point of Application
What are internal forces?
Joint hydrostatic properties
Swelling
Contractile elements
Connective tissue element
What are external forces
Gravity Cuff weights Theraband P.T. manually applied resistance Compressive forces of socket
What are the six non rotary arthrokinematic components?
Forward slide or glide Backward slide Longitudinal or axial distraction Longitudinal or axial compression Left lateral slide Right lateral slide
What are the six rotary osteokinematic components?
Forward bend (flexion) Backward bend (extension) Left lateral bend Right lateral bend Left (axial) rotation Right (axial) Rotation
