Question | Answer |
Posture | Biomechanical alignment of the body.
Orientation of the body to the environment |
Postural Orientation | Vertical for most fx tasks
Active control of body alignment and tone with respect to gravity, support surface, visual environment, and internal references |
Postural Control | Complex motor skill based on the interaction of multiple dynamic sensorimotor processes
involves controlling the position in space for the dual purpose of stability and orientation |
Spatial Orientation | Based on the interpretation of convergent sensory info from somatosensory, vestibular and visual systems |
Postural Stability | Coordination of sensorimotor strategies to stabilize the body's COM during self-initiated and externally triggered disturbances in postural stability
ability to control the COM over the BOS |
Postural Control: Cognitive Influences | Anticipatory Postural control and Adaptive postural control |
Anticipatory Postural control | pretune sensory and motor systems for postural demand based on previous experience |
Adaptive Postural Control | Modification of the sensory and motor systems in response to changing task and environmental demands |
Postural Control: Cognitive influences has 3 components | Attention, Motivation, Intent |
Postural Control: Systems Approach | complex interactions among many bodily systems to control both orientation and stability of the body |
Postural Control: Systems Approach organization | Functional task and environment |
Steady-State balance control | ability to control the COM relative to the BOS
predictable, non-changing conditions |
Movement Strategies | Stability limits, Ankle strategy, hip strategy |
Stability limits | Point at which a person will change the arrangement of their BOS to achieve stability. Impacted by cognitive, perceptual and nature of task |
Ankle Strategy | Used when perturbations in equilibrium are small. requires intact ROM and strength in the ankles. Leg and trunk segments move as a single unit |
Hip Strategy | Used to restore equilibrium in response to larger faster perturbations. Controls motion of the COM by producing large and rapid motions at the hip joint; antiphase rotations at the ankle. Leg and trunk segments move out of phase |
Reactive Balance Control | Ability to recover a stable position following a perturbation. Relies on feed back mechanisms, occurring in response to sensory feedback |
Reactive Control Motor Patterns | Fixed Support
Change in Support
Reach to grasp |
Proactive / Anticipatory Balance Control | Ability to activate muscles in the legs and trunk for balance control in advance of potentially destabilizing voluntary movements |
Proactive Balance Control parameters | Force is preprogrammed based on anticipation of what the task requires
Anticipatory postural muscle activation is critical |
Environmental Constraints | Changes in support surfaces
Differences in visual and surface conditions
Multi-tasking |
Sensory/Perception Systems | Visual Inputs
Somatosensory Inputs
Vestibular Inputs
Sensory Reweighting |
Visual Inputs | provides info about head position and motion with respect to surrounding objects
Not always accurate
important when using change in support strategies |
Somatosensory Inputs | Provides CNS with position and motion info about the body in relation to supporting surfaces
not helpful with moving surfaces or surfaces that are not horizontal |
Vestibular Inputs | Provides CNS with info about the position and movement of the head in relation to gravity and inertial forces
important in proactive balance - provide info about the task and environemnt |
Sensory Reweighting | Reliance on one sensory system for postural control increase while at the same time reliance on another sensory system decrease |
Postural Impairments: Steady-State Balance | Inability to assume and maintain a stable position. use of arms for support and balance which limits use of UE for functional tasks |
Postural Impairment: Alignment | Determines the effort required to support the body against gravity.
Influences how muscles are recruited and coordinated for recovery of stability |