Stance and Posture Flashcards
what is posture?
alignment of body segments
what tool is commonly used to assess posture?
a plum line
what muscles support upright posture?
antigravity muscles
what forces are required to maintain stance?
LOG and muscles
t/f: the extensors have to work to keep up upright
true
postural sway occurs mostly where?
at the ankle
why does postural sway occur?
bc of things inside us moving constantly such as blood flow, digestion, and beating heart which affect the ability to stay still
how much sagittal plane sway is there normally?
12 deg
how much frontal plane sway is there normally?
16 deg
what is the COM?
total body mass and the point where the body is in complete equilibrium
where is the COM normally located?
anterior to S2
what is the LOG?
vertical projection of the COM to the ground
what is stance posture?
balance of forces in stance
what force creates an external moment arm in stance posture?
gravity
t/f: muscles have to contract against the pull of gravity to stay in stance posture
true
where is the LOG at the knee?
anterior to the knee jt but posterior to the patella
what muscles at the knee have to resist the pull of gravity?
posterior muscles and tissues
where is the LOG at the ankle?
4-6 cm anterior to the ankle
what muscle resists the pull of gravity at the ankle?
soleus
where is the LOG at the hip?
posterior to the axis of the hip
what is the normal ASIS-PSIS angle?
12 deg
what is the normal angle of inclination at the sacrum?
30-40 deg inclination
what forces are required for functional stance at the hip?
LOG posterior to the hip axis
slight illiacus activity to counteract gravity
what forces are required for functional stance at the head and trunk?
LOG falls on concavity of spinal curves
thoracic erector spinae active to maintain posture
cervical extensors balance occiput on the atlas
what is the ankle strategy?
control of psture initiated at the ankle
the 1st place where resistance happens
used for small perturbations
what is the hip strategy?
the 2nd place where resistance happens
used for larger perturbations
when are the stepping or reaching strategies used?
perturbations so big that the hip strategy isn’t enough to maintain balance
large, rapid change in COM
what is the BOS?
area of the body in contact w/support surface
what is the COP?
distribution of total force on supporting surface
balance is a combination of the interactions bw what 3 factors?
1) individual
2) environment
3) postural task
what factors are a part of the individual?
muscular and neural systems
postural control systems
what makes up cognition?
attention, motivation, intent
what are factors that make up the environment?
uneven surfaces, ice, moving/changing surfaces, dark/cloudy
what is a steady state?
predictable and steady
least challenging posture
what is proactive state?
activating muscles b4 the action
thinking about how much force you will need to use
what is reactive state?
able to recover from an unexpected purturbance like tripping, getting pushed, etc.
are proactive and reactive actions feedforward or feedback?
both
what is feedback?
responses to things around you
what is feedforward?
anticipation of what’s going to happen
what are adaptations?
refining and tuning response to task demands and environment
how does postural control develop?
cephalocaudal progression (from head down)
head support and vision–>sitting independently–>reaching b4 anticipatory control
head support–>sitting–>reaching
when does lifting the head occur?
1 month
when does sitting w/support occur?
4-7 months
when does sitting w/o support occur?
4-7 months
when does creeping/crawling occur?
8-10 months
what is creeping?
army crawl
both arms moving together to crawl
how is crawling different from creeping?
uses alternating arm instead of both arms at the same time
when does the pull to stand occur?
9-10 months
when does independent stance occur?
12-13 months
when does walking occur?
14-18 months
what tests can be used to evaluate development?
gross motor fxn measure (GMFM)
Peabody developmental motor scale (very common)
movement assessment of infants
what changes in posture occur with aging?
decreased strength, power, activity level
increased fear of falling (FOF)
impacted by lifestyle and activity
very variable
