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NM I - lecture 7
n/a
48
Anatomy
Graduate
06/28/2009

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Cards

Term
Orientation
Definition

ability to maintain and appropriate relationship btwn body segments and btwn the body and environment during tasks

ex: vertical alignment

Term
Stability
Definition

ability to maintain one's COM(center of mass) within the limits of their BOS (base of support)

aka = balance

Term
Name a task where stability is sacrificed for orientation
Definition

reaching for a fly ball while on the run

 

aka: Jacoby Ellsbury # 46

Term
There are 3 systems that are required to maintain postural control...Name them
Definition

1. Sensory system = somatosensation, vestibular and visual imput

2. NM system = CNS integration of information

3. MS = execute postural adjustments

Term
BOS ( base of support)
Definition

during quiet stance = outer rim of the feet in contact with the ground

and center of mass (COM) must be kept within

the BOS to maintain stability

Term
Limits of stability (LOS)
Definition

boundaries within which an individual can move or sway and maintain stability without changing their base of support.

Determined by strenght, ROM, task they are performing and the environment.

Term
Postural Tone
Definition

maintained by mms throughout the body these remain tonically active during quiet stance.

 

MMS = erector spinae, iliopsoas, gastrocs, glute med, abs, TFL, tib ant, soleus, biceps femoris

Term
Optimal alignment
Definition
achieved when the postural mms expend the least amount of energy possible
Term
Adaptive (reactive) postural control
Definition
occurs in response to a destabilizing external force or perturbation - utilizes feedback mechanisms where the CNS responds to information received during or after a movement and attempts to restore stability
Term
Anticipatory (proactive) postural control
Definition
occurs in preparation of self initiated voluntary movements that have the potential to destabilize the body - utilizes feedforward mechanisms where the CNS sends signals to the postural mms in advance of self-initiated mvmt to ready the system and prevent loss of stability - relies of past experience
Term
Ankle strategy
Definition
response to SMALL perturbation on a FIRM support surface mms fire DISTAL to PROXIMAL
Term

Muscle synergy induced by forward sway

(Ankle Strategy)

Definition

pushed forward or platform under the feet moves posteriorly

1. Gastroc>Hams>paraspinals

Term

Muscle synergy induced by backward sway

(ankle strategy)

Definition

being pushed backward or platform under the feet moves in an anterior direction

1. Tib ant>quads>abs

Term
Hip strategy
Definition

occurs in response to LARGE or FAST perturbations or when the support surface is COMPLIANT or very NARROW (balance beam)

- stability restored by producing a large, rapid flexion or extension motion at the hip joint

- fires PROXIMAL to DISTAL

Term
Muscle synergy induced by forward sway at the hip
Definition

push forward or platform moves posteriorly under feet

1. abs>quads

 

Term

Muscle synergy induced by backward sway

of the hip

Definition

push back or platform moves anteriorly

1. Paraspinals>Hamstrings

2. hips extend to restore COM

Term
Stepping strategy
Definition

occurs in repsonse to LARGE and FAST perturbations or when the ankle or trunk musculature is weak - which means that the ankle and hip strategies would be ineffective

- stabilty restored by stepping or hopping in the SAME direction of the perturbation

Term
Mediolateral stability
Definition

being pushed sideways

- most mvmt occurs at hip jt

hip ABD and ADD mm groups control loading and unloading of LEs causing lateral mvmt of the pelvis via relative hip ABD of one LE and ADD of the other - LARGER and FASTER perturbations will result in a crossover step

Term
Sensory mechanisms related to postural control
Definition
to restore stability and use the correct postural strategy the CNS must know where the body is in space and whether or not it is in motion or stationary. Accomplished by organizing and interpreting info from VISUAL, SOMATOSENSORY and VESTIBULAR inputs and the cerebellum plays a critical role interpreting this info for the correct postural response
Term
Visual inputs
Definition

provides the brain with info on the position (verticality) and motion of the head (as the head moves forward/backward surrounding objects move in the opposite direction)

 

Term
Inaccurate visual inputs
Definition
Ex: when driving the car next to you moves forward and you feel like you are too even though you are sitting still
Term
Somatosensation
Definition
provides the brain with info about the position (proprioception) and motion (kinesthesia) of the body with respect to the support surface and the position of body parts relative to one another
Term
Vestibular
Definition
provides the brain with info about the position and mvmt of the head with respect to gravity and inertial forces the semicircular canals sense angular acceleration and the otoliths sense vertical and horizontal acceleration of the head
Term
Which sensory system provides the greatest and most reliable information....which provides the least
Definition

GREATEST = somatosensory>vision>vestibular

 

LEAST = vestibular

Term
Clinical note on sensory system impairments
Definition

if one becomes impaired there will be an acute onset of balance impairment, but the CNS quickly learns to compensate with the remaining to - to restore stability.

If two or more are impaired balance deficits will ensue and likely persist - compensation difficult

Term

SOT (sensory organization test)

or

clinical test for sensory interaction and balance

(CTSIB)

Definition

assesses the adaptation of the CNS with sensory info and assist in determining whether or not one of the 3 senses is impaired or absent

= uses a tilting platform, blindfold, and moving visual surround that moves with body sway 

Term

SOT/CTSIB

measures body sway under 6 different conditions

name them

Definition

1. normal vision - fixed support

2. absent vision - fixed support

3. sway/referenced vision - fixed support

4. normal vision - sway referenced support

5. absent vision - sway referenced support

6. sway referenced vision & support

Term
FOAM and DOME test
Definition

developed by Shumway-Cook & Horak

- simplified SOT/CTSIB

used medium density foam to reduce somatosensory input & DOME placed over individuals head for inaccurate visual info or visual conflict

- young neurologically intact adults should be able to stand for 30 sec for each of the 6 conditions

Term
What are the 6 conditions for the FOAM and DOME??
Definition

1. eyes open - on ground

2. eyes closed - on ground

3. dome on head - on ground

4. eyes open - on pad

5. eyes closed - on pad

6. dome on head - on pad

Term
NM balance impairments... mm sequencing problems during activation of postural strategies
Definition

postural synergy mms are activated in the WRONG order

EX: individual may activate abs before tib ant during a SMALL posterior perturbation

Term
NM balance impairments...co-activation of antagonist mms
Definition

both the ant and post postural synergy mms fire, REGARDLESS of the DIRECTION of perturbation

Ex: Parkinson's - riggidity affects both sides of the jt

Term
NM balance impairments...delayed activation of postural synergies
Definition

individual will appear unsteady and easily lose stability

Ex: pt perturbed backwards they may resort to a stepping strategy instead of an ankle strategy

Term
NM balance impairments...difficulty scaling the amplitude of postural synergy
Definition

reduced ability to increase the amplitude of response to increasing levels of perturbations

ie (weak mms synergy response will occur regardless of strength of perturbation or excessive mms synergy response to a small perturbation)

Term

NM balance impairments...

Hypermetria

Definition

a later scaling problem that causes excessive compensatory sway in the direction OPPOSITE of the initial direction of instability

Ex: pushing an individual post they will overcompensate and excessively sway in an anterior direction possibly falling forward

Term
A lesion in which area of the brain is likely to result in an hypermetric scaling problem
Definition
CEREBELLUM
Term

NM balance impairments...

Motor adaptation problems

Definition

individuals with NM lesion may become fixed in stereotyped patterns of mvmt and be unable to adapt the postural synergy to the environment or size of perturbation.

Ex: ankle synergy used regardless of compliancy of support surface or size of perturbation

Term
Muscle Paresis
Definition
weakness will render the postural strategies ineffective
Term

NM balance impairments...

What neurological diagnosis is likely to have motor adaptation problems

Definition
Stroke victims - tend to move in stereotypical patterns
Term

NM balance impairments...

loss of anticipatory control

Definition

may cause instability and loss of balance during self-initiated mvmts such as reaching, lifting, and carrying

difficult to treat

Term
MS impairments (indirect) and constraints
Definition

1. Disuse atrophy

2. muscle stiffness and loss of ROM

3. abnormal postural alignment (forward flxed kyphotic posture)

4. use of AFO (contractures of the brace because it holds the ankle at 90 degrees)

Term
Impaired cognitive function and postural control
Definition
individuals with UMN lesions often demonstrate cognitive impairments and recent research has demonstrated a relationship btwn cognitive impairment and postural instability thus the more cognitively impaired the more impaired their balance will be. Also, pts with dementia have posture problems and prone to falls
Term
Impaired postural control under dual task conditions (multi-tasking)
Definition
UMN lesions are engaged in a balance task along with either a secondary motor task (narrow BOS) or a cognitive test (standing>narrow>counting backwards) = postural sway will increase more than a normally healthy individual
Term
Clinical assessment of balance:
Definition

tested in seated and standing, static and dynamic components are assessed, as well as

anticipatory and adaptive postural control

Term
Static balance
Definition

ability to independently maintain COM within BOS

aka = ability to hold a static position

EX: reaching arms but not moving outside of BOS

** should maintain static balance for 30 sec

Term
Anticipatory control test:
Definition

static = ask pt to raise arms while maintaining static seated or standing position

dynamic = ask pt to reach outside BOS

Term
Adaptive postural control (test)
Definition

static = pt seated nudge them in multiple directions or ask pt to close eyes or stand/sit on foam

dynamic = nudge pt in multiple directions while reaching outside BOS can also be done standing or sitting on foam 

Term
Dynamic balance
Definition
ability to maintain COM over BOS or independently recovers stability when COM approaches their limits of stability
Term
Standardized functional assessments
Definition
  1. timed up and go
  2. Berg Balance
  3. Functional reach
  4. Tinetti
  5. Romberg and sharpened Romberg
  6. Foam and Dome
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