M1 L7b: Ax Postural control II - Contributing Systems Flashcards
What are7 factors that have a complex interaction in the systems approach- BF & S?
What are 7 characteristics of neuromuscular synergies?
- Set number of strategies used by the CNS
- Prevent loss of balance by correcting the displacement of the COM and to keep it within the BOS in the event of an unpredictable perturbation (Eg. slip, trip)
- Discrete strategies are demonstrated with a fixed BOS and movement of a platform in the sagittal plane
- However when task conditions are altered, such as speed of the platform perturbation, a combination of strategies are used
- Therefore under normal conditions of an unexpected perturbation, such as a slip or trip, a postural continuum with a combination of strategies may be used
- Under these conditions the competency of the adaptive mechanisms are important
What are the ankle, hip and stepping strategies?
What are 3 characteristics of adaptive mechanisms?
- Use feedback from the sensory and motor system
- More variable corrective component than neuromuscular synergies
- Used after both unexpected (eg. slip, trip) and expected perturbations (eg. stand up)
What are the 4 stages of development of adaptive mechanism (from 2 months to 4-6yrs)?
- First level response to develop
- Development of direction specific patterns and fine tuning
- Required to develop head control, sitting and standing
- In supine neck muscle responses develops at around 2months (Look left and right (while in supine))
- Sitting – emerges from 3-5 months and develops until 3 years with fine tuning until adulthood (Biomedical responses (eg. growth spurt))
- Standing – emerges 7-8 months and adult like 7-10 years
- Especially variable during transitional period 4-6y
What are 3 anticipatory mechanisms?
- Feed forward system of postural control
- Pre-tuning of the sensory and motor systems prior to movement
- Maintain equilibrium
- Based on predictions made by the CNS
- Based on information present and past experiences
What does adaptive VS anticipatory muscle activation look like?
What are 6 stages in the development of anticipatory mechanism?
Follows a similar course to adaptive development but may be more affected by practice and learning
- Sitting and reaching: present at 9 months
- Standing: early responses 12-15mths; more mature 4-6yrs
- Anticipatory activation consistently present from 8years
- No gender differences in pattern 8 -12 yrs
- Respond to task constraints at 8y (accuracy, posture, dual-task)
- Adolescents nearing adult patterns
What are the 2 individual sensory systems?
- The sensory systems, including the tactile, visual, somatosensory and vestibular systems
- Provides information to the CNS of the body’s position and movement
What are sensory strategies?
How information is organized and interpreted from individual sensory systems contributes to postural control.
What is the sensory role of tactile?
orients body to the stimulus
What is the sensory role of vestibular?
central reference for other systems
What are the 3 sensory roles of proprioception?
- Relative position of body parts
- Orient to support surface
- Joint position sense, muscle length
What are the 3 sensory roles of vision?
- Motivates to move
- React to optic flow 5-7m
- Orient to visual surrounds by 6m (OHR)
What are 3 characteristics (systems) of the development of sensory systems from in utero?
- In utero
- Tactile
- response to stimulus by 3w
- Vestibular and proprioception
- Not clear how early
- Baby rolls, somersaults, sucks thumb
- Could be tactile too
What are 4 characteristics (systems) of the development of sensory systems from birth (newborn)?
- Tactile (also smell)
- Primary senses soon after birth, later vision becomes primary
- Vision
- Preterm infant can follow but not focus until term
- In infants, drives exploratory behaviour, drives movement
- Proprioception
- Present at / soon after birth
- Vestibular system
- Drives the HR response initially (3-6m) then vision takes over as system matures (6m+)
What are 2 characteristics (systems) of the development of sensory systems from 2-3 years?
- Vision dominates
- Proprioception & vestibular contribute (e.g. eyes shut)
What are 3 characteristics (systems) of the development of sensory systems from 4-6 years?
- Very variable (transitional phase)- growth spurt?
- Tactile largely mature by 4y
- Proprioception - body parts mature at different rates
What are 3 characteristics (systems) of the development of sensory systems from 7-8+ years?
- Prop from feet
- Vision less important (more adult type) unless learning new skill
- Vestibular mature by about 9y
What are 5 musculoskeletal components that postural control can be affected by?
- Growth
- Body alignment
- Muscle and postural tone
- Muscle strength
- Joint range of movement
What are 3 proportional changes in shape and height (growth)?
- head v body size in and infant v adult
- limb length, trunk length
- growth of organs and soft tissues
What is the biomechanical implications of growth in terms of changes in shape and height?
COG in infants = T12, adults = L5
What are the 4 stages of development of body alignment?
- Birth 1° flexor curves (cervical spine)
- 3-6 months mobile Cx ext curve
- 8 months mobile Lx ext curve
- childhood & adults: 2 flexor and 2 extensor curves
What are internal respresentations?
- Internal representations provide a postural frame of reference or schematic representation of body geometry, dynamics (kinetics and kinematics) and orientation to vertical
- Actions are related to sensory inputs to develop maps or internal representation of body schema.
