Posture-balance Flashcards
Both posture and balance require _____ _____ effort to counterbalance the external forces acting upon the body
active neuromuscular
_____ is the predominant force acting upon the body, which also interacts with any loads we attach to the body
gravity
posture is established and maintained through the activation of the “antigravity muscles” that act upon the _____skeleton
axial
activation of “antigravity muscles” generates muscle _____, which provides “resistance” by the muscle to _____ caused by external loads
tone; stretch (locking muscle length)
muscle tone is often viewed as the overall _____ of the muscle arising from active force generation
stiffness
postural muscle tone is established through a sustained, but _____ level of activation to maintain a “counterforce” level of tension in opposition to the external loads
variable
_____ is established and maintained by aligning the body’s center of mass over its base of support, and by stabilizing and supporting the body whenever its center of mass moves _____ from its base of support
Balance; away
A point that represents the average position of the body’s total mass … the net effect of gravity upon the body is through its center of mass. What is this known as?
Center of mass
What is base of support?
the ground, or platform upon which we make contact (e.g.with our feet), to which the gravitational force, acting through the body’s center of mass, is applied
Is posture and balance interrelated?
Yes
posture establishes the “geometry” between the body’s _____ and its
current _____.
center of mass; “stance”
whenever the center of mass is “displaced”, “_____ _____ vectors” must become activated to prevent a loss of balance
“counteracting force vectors”
“force vectors”: _____ forces, established through muscle _____, to counteract external forces that would otherwise push the body off balance
pulling; activation
when muscle activation is insufficient to counteract the loss of balance, we must then _____ relative to the center of gravity to re-establish balance
alter our stance
Change of posture may put the body _____.
Unbalanced
Maintaining balance requires _____ _____.
“postural equilibrium”
_____ _____ is achieved when the “counter-force” muscles are appropriately activated to provide the force needed to offset the displacement forces that would otherwise throw the body off balance
postural equilibrium
The specific pattern of muscle activation will be _____ dependent, and may often also involve ______ learning
context; experience-based
Muscles activated to maintain postural equilibrium provide _____ against the forces that would otherwise cause a loss of balance
compensation
Forward and backward _____ are shifting the center of mass relative to the base of support.
sway
What are the 2 forms of compensation of loss of balance?
- Counteract the initial displacement
2. Stabilize and brace the body through active counteracting force vectors
What is the sequential order for compensatory activation of muscles if there is disturbance to postural equilibrium?
- Those closest to the origin of displacement are activated first, to COUNTER ACT.
- compensatory muscle activation continues progressively moving away from the origin of displacement, to STABILIZE and BRACE.
Compensatory motor responses to counteract a disturbance in posture are activated reflexively. What are the sensory inputs?
Proprioceptive and vestibular, along with visual.
(T/F) Postural adjustments often improve upon repeated trial.
True
During forward sway, is gastrocnemius muscle contracted or inhibited?
Contracted
During tilt (hilly) of the ground surface, is gastrocnemius muscle contracted or inhibited?
Inhibited
Postural adjustment can be _____ through experience that may be executed in advance of a stimulus.
learned
_____ awareness contributes towards deciding upon which postural set “program” to activate
Perceptual
Without support, gastrocnemius muscle and hamstring muscles are (activated/inactivated) in advance of biceps to prevent forward sway induced by pulling agains the handle.
Activated
With the body supported, gastrocnemius muscle and hamstring muscles are (activated/inactivated) in advance of biceps to prevent forward sway induced by pulling agains the handle.
Inactivated
Before initiating voluntary movements when the body is unsupported, a compensatory postural adjustment will normally be _____ in advance of activation of the movement itself
initiated/activated
“central command” refers to the motor signals that will execute the intended movement – (2 types of signaling)
Feedforward and feedback signaling
What is feedforward?
Anticipatory motor commands (Postural adjustment)
What is feedback signaling?
Acting through motor reflexes (Fine adjustments)
Awareness of current body position, and of intended movement generates
adjustments in muscle tone in advance of the initiation of voluntary movement. (Feedforward or Feedback signaling?)
Feedforward
Such responses are automatic and rapid, and scale in magnitude relative to forces and motions to achieve and maintain stable posture. (Feedforward or feedback signaling?)
Feedback
Can feedback response be improved through learning and practice?
Yes!
Feedforward/feedback is anticipatory
Feedforward
Feedforward/feedback is compensatory
Feedback
Posture and balance are monitored and maintained by three primary sensory systems:
Proprioceptive, vestibular, and visual
Proprioceptors report changes in orientation and balance via changes in the_____ and _____ of specific muscles.
length and tension
Which sensory system has the SHORTEST latency?
Proprioceptive (fastest to respond)
Which sensory system reports head motion?
Vestibular receptors
Which sensory system reports motion relative to external objects in the visual field?
Visual input
Vestibular and visual responses are almost _____ as slow as proprioceptive responses.
twice
Afferent input from just one sensory system may lead to _____ by the brain that could lead to an inappropriate postural adjustment.
“misinterpretations”
Effective postural adjustments therefore require the integration of more than one sensory input, so as to generate the appropriate _____ _____.
sensorimotor transformations
Which sensory system provide feedback into spinal cord motor neurons and motor circuits to provide rapid “antigravity stabilization”?
Proprioceptive feedback
What is “antigravity stabilization”?
Counterforce applied against gravitational weight
(T/F) Maintaining balance when challenged by continuously varying (or dynamic) loads upon the body and/or during active movements requires the integration of additional sensory inputs (vestibular and visual).
True
Integration of visual and vestibular sensory inputs is largely _____involving nuclei within the brainstem and cerebellum.
sub-cortical
