Describe how humans maintain postural stability when standing Flashcards
How do humans maintain postural stability when standing?
Though interactions of sensory and motor control systems like the visual, vestibular (balance), and somatosensory (touch and proprioception)
What role does the visual system play in maintaining postural stability?
It provides information about the body’s position and movement, eg. if we are standing still, if the environment is stable or not
What role does the vestibular system play in maintaining postural stability?
Located in the inner ear, it sense the position/ movement of the head, translates these signals into motor responses to maintain stability. Useful when visual systems fail, eg. in the dark
What role does the somatosensory system play in maintaining postural stability?
It provides information about the position and movement of different body parts + the contact forces between the body and support surface. eg. if weight is evenly distributed, also responsible for proprioception
How does the central nervous system aid in maintaining postural stability?
The sensory systems provides feedback to the CNS (includes the brain/spinal cord) which then generates appropriate motor responses to maintain balance
What is the motor response from the CNS?
Coordinated contractions of various muscles to prevent loss of balance. eg. if a person starts to lean forward the CNS will sense and contract muscles at back of legs and lower back keeping and upright position.
What are anticipatory postural adjustments?
Predictive motor responses that are initiated before a voluntary movement. eg. if you lean down to pick up a box when sitting muscles in your back will tense to keep you from falling out of a chair
What is balance defined as?
Balance is the equilibrium resulting from the matching of torques, which can be organized in anticipation of, or as a reaction to, the effects of postural disturbance
What is an example of maintaining balance?
Initial posture is with COM slightly forward of ankle joint; gravity acting vertically down exerts a small net torque at the ankle, keeping balanced involves the calf muscles exerting a steady counter torque
What happens when balance perturbation is large?
If it is too large to resist (the net force through the OM projects outside the support base provided by the feet) then people may chose to take a step to recover
What is a postural syngery
A preferred pattern of muscle co-activation that is used by the CNS to maintain standing balance
What can you conclude about postural synergies?
Based on a paper “The dynamics of standing balance” it can be concluded that postural synergies are flexible and can be activated or assembled by task parameters which are sensitive to biomechanical constraints or attentional factors.
What is an example of flexible postural synergies?
There is reduced mediolateral sway and increased anteroposterior sway when shooting a gun that is oriented parallel to the sagittal plane of the body.
What can be concluded about how humans maintain postural stability when standing?
The ability to recover balance or adapt to varying contexts largely depends on the tasks one is engaged in while maintaining balance.
