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