Postural Control

Question 1

postural control

Answer 1

• maintaining body alignment
• maintaining balance in the face of external disturbing forces such as gravity
• maintaining balance in the face of self-generated forces during movement

Question 2

3 developmental progressions

Answer 2

• head control
• sit
• stand

Question 3

head control

Answer 3

hold steady while moving, back muscles activate

Question 4

sit

Answer 4

sits without support, sits alone with good coordination, and gets to sitting (lying -> sitting)

Question 5

stand

Answer 5

pulls to standing, stands alone

Question 6

3 developmental progression trends

Answer 6

• cephalocaudal progression of control of joints
• flex dominated positions -> extensor dominated positions

Question 7

sway

Answer 7

motion about a central equilibrium axis, disturbance -> system not mature

Question 8

3 main classes of sensors

Answer 8

vision, vestibular sensors, somatosensors/body sensors

Question 9

vision sensors

Answer 9

take images in, what we see, whats going on around the head, interpreted in brain (in head)

Question 10

vestibular sensors

Answer 10

linear, rotational movement, inner ear (in head)

Question 11

somatosensors/body sensors

Answer 11

receptors found in muscle used to help determined position in rest of the body

Question 12

CNS uses combination of these 3 systems to rapidly figure out..

Answer 12

why swaying, how much sway, and then what muscles need to contract to fix it

Question 13

we know from milestones..

Answer 13

• postural control progresses from head/shoulders (1 joint)
  only need first 2 sensors
• to sitting (2 joints)
• to standing (many joints)
• brain needs to relearn for each new stage

Question 14

visual dominance during stage 1

Answer 14

development of head control

Question 15

how do we know a newborn is developing visual dominance?

Answer 15

• newborn in room with vertical stripes
  –stripes twist
  –neck muscles contract as if trying to follow the movement of the stripes
• if visual info is blocked and body or head is twisted, don’t get the same response
• therefore, at this stage, infant has a visually dominant system
• no evidence of vestibular or somatosensory sensors until several months later

Question 16

early head/neck control

Answer 16

not limited by inadequate strength (learn to take in appropriate sensory info)

Question 17

~3-4 months

Answer 17

• child will exhibit an appropriate neck response to sway 40-60% of the time
• something has to happen between 3-4 months and 6-7 months, when the infant can sit upright

Question 18

~ 6 months

Answer 18

• infant reaches “sloppy sitting” (hunched/leaning on belly) milestone
  — ignoring body info
  — independent sitting is more complicated
  — 2 joints to control
  — interaction torque
• sway control begins to appear 6-7 months
  — using sensory signals from the neck to control the head
• not exclusively visually dominant for head control *
• start to trust somatosensors (rely on visual sensors first)

Question 19

independent sitting requires..

Answer 19

head plus trunk control, plus the ability to control sway (motion about a vertical equilibrium axis)

Question 20

sway control during upright sitting appears around 6-7 months

Answer 20

• appropriate neck muscle responses to induced sway occur 40-60% of the time by 3-4 months
• by 5-8 months, neck muscle responses become progressively coordinated with trunk responses

Question 21

sensory information for sitting

Answer 21

vision dominates early and gradually gives way to somatosensory information from the hips (starting to trust)

Question 22

moving room - sitting

Answer 22

• adult: nothing would happen in moving box bc system is mature
• sitting infant: will fall when box is moved
  — behavior continues from about 3 months after milestone is reached
  — after 3 months, infant trusts somatosensors instead of visual sensors

Question 23

independent stance

Answer 23

• strength doesn’t limit development
• coordinated muscle responses to platform disturbances
• vision is first source of sensory information and lessens in dominance in experienced walkers
• somatosensory info to muscles controlling stance occurs around 9 months and strengthens as walking experience accumulates

Question 24

moving room - standing

Answer 24

• child is upright and independently controlling sway ~11-12 months of age
• put in room while standing: child will fall for about 3 months, new milestones revert back to visual sensors

Question 25

visually dominant first at each stage

Answer 25

holding up head, sitting, and standing

Question 26

hydraulic platform

Answer 26

• backward movement of platform causes the equivalent of forward sway
• forward movement of platform causes the equivalent of backward sway

Question 27

ankle strategy

Answer 27

• used when disturbance is small
• used when contact surface is wide and firm
• muscles are recruited inferior to superior
• head movements are aligned with body

Question 28

ankle strategy forward sway

Answer 28

calf, hamstring, posterior muscles

Question 29

ankle strategy backward sway

Answer 29

tibia, quads, then abdominals

Question 30

hip strategy

Answer 30

• used when disturbance is large
• used when surface is unstable
• muscles are recruited superior to inferior
• head movement is opposite of hips

Question 31

hip strategy forward sway

Answer 31

abdominal muscles then quads

Question 32

hip strategy backward sway

Answer 32

posterior muscles then hamstrings

Question 33

it takes ____ years for sway mechanism to fully develop

Answer 33

7-11

Question 34

as the developing brain gets better at incorporating muscles into adult-like patterns, sway gets better

Answer 34

mostly increase appropriate muscles contracting

Question 35

can maturation be accelerated with balance training?

Answer 35

muscle response increases so yes possible to accelerate balance control

Question 36

other options with platform device

Answer 36

• can attach canopy that moves when the ankles move
• platform can rotate forward with ankle movement (eliminates feedback from the feet and ankles)

Question 37

which sensors are most important?

Answer 37

somatosensors

Question 38

2 types of postural adjustments

Answer 38

reactive and anticipatory

Question 39

reactive

Answer 39

respond to disturbance

Question 40

anticipatory

Answer 40

prior to predictable movement

Question 41

when do you see these postural adjustments?

Answer 41

9-12 months