Postural Control
Ankle strategy occurs _____ to ____. (proximal/distal)
distal to proximal
_______ tone is the activation of antigravity muscles to keep us against the pull of gravity
postural
T/F Attention, motivation, and intent all affect postural control
Tru
_____ Restores the COM to a position of stability through body movement centered around the ankle joints
ankle strategy for A-P stability
Walking in a quiet room, in the mall while talking, or in the grocery store on the phone are all examples of ____ strategies
attentional
A ____ limit is the boundary the body can maintain balance without changing the base of support
stability
____ is the ability to control the center of mass in relationship to its base of support
stability (balance)
The (COP/BOS) moves continuously around the COM to keep the COM within the (COP/BOS)
- COP -BOS
Describe control lateral sway
- adduction of one leg and abduction of the other -head movements occur first, then hip, ankle -head moves in opposite direction to hip, ankles
Describe the vertical line of gravity at quiet stance
- midline between the mastoid process - Point just in front of shoulder joints (upper back) - Hip joints or just behind (psoas) - Point just in front of center of knee joints (hamstrings) - Slight anterior to the ankle joint (gastroc)
Rank these in order in trying not to fall - stepping strategy - hip strategy -ankle strategy
-ankle, then hip, then stepping
The preparatory phase for movement is where postural muscles activate 50ms before prime movers. This is (feedforward/feedback) In the compensatory phase, the postural muscles activate after prime movers. This is (feedforward/feedback)
-feedforward -feedback
A man is sitting on a bench reading a book. Describe the task including BOS and orientation
BOS is feet and bench Orientation is the hand and arm holding the book with elbow bent
What do all these stand for?? COM, COG, COP
COM - center of mass COG - center of gravity COP - center of pressure
Match COP, COG, and COM to these 1) the vertical projection of the center of mass to the ground 2) a point that is at the center of total body mass 3) the center of the distribution of the total force applied to the supporting surface
COP - 3 COG - 1 COM - 2
T/F A larger BOS is less stable than a narrow one
False
T/F There is an EMG signal at quiet stance
False
________ Controls motion of COM by producing large and rapid motion at hip joints with antiphase rotations of the ankles
Hip strategy for A-P stability
These all describe what? A neural organization of a multi-element system Simplifies the control demands on the CNS These synergies are flexible and alter in task dependent manner Some muscles in synergies are tightly coupled; other muscles activity highly modifiable.
Muscle synergy
Standing on a firm surface without a blindfold will give inaccurate info about ______.
None of the 3 systems. All 3 are accurate
When would a medial-lateral strategy be used for stability?
Primarily used hip joint and trunk when recovering stability in the medio-lateral direction
When sitting on a nonmoving chair, what is the base of support?
The entire chair and the person's feet
If you are sitting reading in a moving bus, what is different than if you were doing the same on a bench?
The person on the bus has to constantly adapt to her orientation and stability
T/F A heavier mass is more stable
True
T/F In walking, the COM moves outside the BOS sometimes
True
Standing on a non-firm surface with a blindfold will give inaccurate info about ______. It will give accurate info from the ______ system(s).
accurate: vestibular inaccurate: somatosensory
Standing on a non-firm surface with sway-referenced vision will give inaccurate info about ______. It will give accurate info from the ______ system(s).
accurate: vestibular inaccurate: vision, somatosensory
____ mechanisms involve modifying the sensory and motor systems in response to changing task and environmental demands
adaptive
_____ is the ability to modify sensory and motor systems in response to changing task and environmental demands
adaptive postural control
____ mechanisms involve pretuning sensory and motor systems for postural demands based on previous experience and learning
anticipatory
As the height of center of mass increases, stability will ____
decrease
A scalar distance between the COP and the COM at any given point in time is the ______
error signal
The ______ is used to drive the postural control system during balance
error signal
What do these sensory inputs do during quiet stance? - sensors on soles of feet - sensors in neck - visual and vestibular input
feet: increases extensor muscle tone neck: responds to changes in head orientation visual/vestib: affects tone
In forward sway (ankle strategy), what muscles activate? Backward sway?
forward: gastrocs, hamstrings, paraspinals backward: tibialis anterior, quads, abdominals
What are the active muscles in medial-lateral stability
gluteus medius, TFL, abductor and adductor muscle groups
Standing on a non-firm surface without a blindfold will give inaccurate info about ______. It will give accurate info from the ______ system(s).
inaccurate: somatosensory accurate: vestibular, vision
Standing on a firm surface with sway-referenced vision will give inaccurate info about ______. It will give accurate info from the ______ system(s).
inaccurate: vision accurate: vestibular, somatosensory
______ stability is organized proximal to distal
medial-lateral
___ keeps the body from collapsing in response to gravity
muscle tone
____ involves controlling the body's position in space for the dual purposes of stability and orientation
postural control
_______ is the ability to maintain an appropriate relationship between body segments, and between the body and environment for a task using multiple sensory references
postural orientation
Age, injury, bracing, fatigue, obesity, stability of the external environment are all factors that affect _________ strategy
postural sway
What is the role of the iliopsoas at quiet stance?
prevent hip hyperextension
____ is postural stability or balance ability to maintain the projected COM within the limits of the BOS
quiet stance
______ is characterized by small amounts of spontaneous postural sway
quiet stance
The Inter-modal Theory of Sensory Organization states that all 3 systems of stability are equal. The sensory weighting hypothesis states that they are dependent on the situation. Which of these is better?
sensory weighting hypothesis
A slower motion will allow you to (reach/exceed) your stability limit. A faster motion will cause you to (exceed/reach) them.
slow - reach fast - exceed
What are the 8 muscles active at quiet stance?
soleus, gastrocs, tibialis anterior, gluteus medius, TFL, erector spinae, abdonimals, iliopsoas
The ____ system gives proprioception, cutaneous, and joint receptor information
somatosensory
The ____ system gives the brain info on -position and motion of the body with reference to supporting surface -Relationship of one body segment to another
somatosensory
Which strategy for A-P stability is the one where a change in BOS is needed?
stepping
______ is when other strategies are insufficient to recover balance, a reach or a step is used to realign the base of support under COM
stepping strategy for A-P stability
Define orientation
the ability to maintain an appropriate relationship between the body segments, and between the body and environment for the task
Define a base of support
the area of the body that is in contact with the support surface
What info do you receive from the vestibular system? Somatosensory? Visual?
vesti: gravity and inertial info somato: feedback of contact visual: both and how are you related to a task
The ______ system provides information on position and movement of head with respect to gravity and inertial forces
vestibular
Standing on a firm surface with a blindfold will give inaccurate info about ______. It will give accurate info from the ______ system(s).
vestibular and somatosensory
In ____ inputs, the brain cannot tell if you or the environment is moving
visual
_____ inputs give info regarding position and motion of the head with respect to surrounding objects
visual
As adults just learn a task, they have an increased reliance on ____ inputs. When they are getting more automatic with the task, this decreases and a reliance on ____ inputs increases
visual somatosensory
What 3 sensory systems feed into the CNS for balance and orientation?
visual, vestibular, proprioceptive
When does the tibialis anterior activate at quiet stance?
when the body sways backwards