Slide 1-39 Flashcards
What is the COM
The point where all the mass of the object is concentrated
WHHATS COG
The point at which the force of gravity seems to be concentrated ( the average location of the weight of an object
What is the Plumb line or ideal gravity line
A vertical line representing gravity that passes through a systems center of mass/gravity
What is the BOS
Base of support
Area bound by regions of contact between the body and support surface or surfaces
What is balance
Aka stability
Ability to maintain center of gravity of an object within base of support
What is perturbation
Disruption of equilibrium
What are stability limits
Boundaries within which the body can maintain stability balance without changing BOS
What 5 mechanical factors impact stability
- BOS
- Height of COG over BOS
- Location of COG within BOS
- Body weight/ mass
- Friction
What is posture
The stereotypical alignment of body/limb segments
What are the types of posture
Static- standing, sitting, lying
Dynamic- walking/running, lifting
How do primary postural muscles work
Generate torque across joints to resist the tendency to be overthrown
How does the body maintain balance
Keeping the body’s COG over BOS
What is dynamic stability
The postural control process of controlling the body in space
What is feedforward control
Anticipatory postural control
Postural responses are made prior to voluntary movement that is potentially destabilizing
What is feedback control
Compensatory or reactive postural responses
Sensory feed back from unexpected external perturbations triggers postural responses
To maintain balance we integrate three inputs
Visual
Vestibular
Proprioceptive
How do you test the visual contribution to balance
Romberg test
How do we test vestibular contribution to balance
Calorific reflex test
How do we test contribution of proprioceptive to balance
Stand on unstable surface
In flat back the thoracic spine is ________ and the lumbar lordosis ___________
Decreased kyphosis
Decreased lumbar lordosis
In sway back the thoracic spine is __________ and the lordosis ___________
Increased kyphosis
Decreased lordosis
How much does ever inch of forward head carriage effect the weight of the head on the spine
10 pounds per inch
What is the kinetic chain
Combination of several successively arranged joints constituting a complex motor unit
What is open chain movement
Kinetic chain in the which the terminal segment can move freely
What is closed chain movement
Kinetic chain in which the distal end of the extremity is fixed
Example of chain movements
Open- bicep curl, bench press
Closed- push ups. Squats
What is the step
The movement of ONE lower extremity from toe off to heel contact
What is stride
TWO steps which each leg= 1 stride
Also called a gait cycle
What is double support
The portion of one gait cycle in which both feet are in contact with the ground
What is flight/float
Neither foot is in contact with the ground
What distinguishes walking from running
Flight/float
One complete gait cycle consists of
The movement when the foot first contacts the ground until that same foot again makes ground contact
What is stance
LE is contacting the ground
Whats swing
LE swinging through the air preparing for next impact
How long does a typical walking gait cycle last
1 second
Stance phase is when the
Distal end is fixed by ground reactive forces, closed chain motion
What are the 3 sub phases of stance phase
Contact
Midstance
Propulsive
What is more percentage stance or swing phase
Stance=60%
Swing= 40%
In the swing phase the kinetic chain is
Freely mobile so this is an open chain motion
How many gait cycles are performed daily
5000
What is the first 1/3 of the stance phase
Contact- begins at the heel strike and ends when entire forefoot makes gourd contact (foot flat)
What is loading response
Interval when the sole of the foot comes into contact with the ground and the WEIGHT OF THE BODY IS ACCEPTED ONTO THE SUPPORTING LIMB
What is the second 1/3 of the stance phase
Midstance
Ends at the point of heel off/ push off
What is the final 1/3 of the stance phase
Propulsive- begins the moment heel leave the ground
During running how are the 3 phases of the “stance” phase divided
Contact- 20%
Midstance- 25%
Propulsive- 55%
What are the three phases of the swing phase
Acceleration
Midswing
Deceleration
When does acceleration begin
When toe off
Midswing ends when the tibia is
Vertical and the swinging leg is forward
When does deceleration end
With the heel strike
