Posture Flashcards
Static Posture
Body and its segments are aligned and maintained in certain positions
Dynamic Posture
Postures in which the body or segments are moving
Base of Support (BOS)
Area enclosed by the outermost edges of the body in contact with the supporting surface
Where is your typical center of mass during static posture?
Just anterior to s1 or s2
Using an assistive device ___________ the BOS, providing _________________________
increases
more postural stability
Postural Control
person’s ability to maintain stability of the body and body segments in response to postural threats
How do you maintain postural control? (3)
Maintaining COM within BOS
Control body’s orientation in space
Maintaining erect posture requires integration of CNS and PNS
Define Postural Sway
oscillations in COM occurring in A/P and M/L direction
COP (center of pressure) corrals COM to maintain postural control
Increased postural sway indicative of _________ postural control challenge… what does this do?
Increased
Decreased stability: Increased risk for falls due to difficulty keeping COM within BOS
What can increase sway?
Hemiparesis Peripheral neuropathy Concussion Vestibular dysfunction Pes Planus
Reactive (compensatory) response in postural control are…
Responses occur as reactions to external destabilizing forces
Proactive (anticipatory) responses in postural control are…
Responses occur in anticipation of internally destabilizing forces
Posture may be altered and stability may be compromised with…
altered or absent inputs
I.e. Decreased sensation of the lower extremities or post-injury
Alterations in outputs also compromise posture. What does this mean?
inability of muscles to respond appropriately to signals from CNS due to a neuromuscular disorder
In a normally functioning CNS, we will select the most efficient combination of muscles to completely the task after analyzing _______________. This creates ________________.
Sensory input
Dynamic control
Sensory Perturbation: may be caused by _____________________________
altering sensory input
Mechanical Perturbation: displacement causing changes in the relationship of the body’s ____________________
CoM to
BoS
Muscle strategies are centrally organized patterns of muscle activity that occur in response to…
Perturbations of standing postures
Describe ankle strategies/synergy
Discrete bursts of muscle activity that occur in a distal-to- proximal pattern
Describe hip synergy/strategy
Discrete bursts of muscle activity that occur in a proximal-to-distal pattern
Alternate Balance Strategies
move or enlarge the body’s BOS so that it remains under the COM
Only strategies that are successful with a large perturbations
Stepping strategies involve taking steps in what directions
Forward
Backward
Lateral
Grasping strategies are
Using one’s hands to grab on a fixed surface
What is the normal recruitment of postural control strategies occurring from small perturbations to large perturbations?
Ankle > hip > stepping > grasping
Ground Reaction Force (GRF)
Force of the ground pushing back on the body in standing
Line of Gravity (LOG)
Extending from COM to the base of support
Center of Pressure (COP)
Point of application of the GRF
Located between the feet in bilateral stance
If LOG passes through a joint axis:
No torque created around the joint
If LOG passes outside the joint axis
External gravitation moment
Results in rotation around the joint axis unless it is opposed by a counterbalancing internal moment
Magnitude of the external moment ___________ as the distance between the LOG and joint axis increases
Increases
Direction depends on the location of the ______ in relation to the joint axis
LOG
Goals of postural assessment
Appreciate static positioning of body segments with relation to each other
Relate back to patient’s main complaints
Apply to potential functional impairments
Keys to success for a postural assessment
Assess from multiple angles
Remove obstructive clothing
Observe more than the area of complaint
Where is the LOG in ideal standing posture? Why?
LOG passes through or very close to all joint axes
Minimizes external moments
External moments are balanced by internal moments
Long term deviations to standing posture result in
Structural changes
Where is the LOG passing through in ideal standing posture from the side view
. Slightly posterior to the apex of the coronal suture
• Through the external auditory meatus*
• Through the odontoid process of the axis
• Midway through the shoulder*
• Through the bodies of the lumbar vertebrae
• Through the sacral promontory
• Slightly posterior to the center of the hip joint*
• Slightly anterior to the axis of the knee joint*
• Slightly anterior to the lateral malleolus*
• Through calcaneocuboid joint
LOG is anterior to knee joint axis
External moment:
extension
Possible additional extension moment contributed by soleus contraction
LOG passes slightly anterior to lateral malleolus
Creating an external moment of
Dorsiflexion
To maintain static posture the internal moment of the ankle is..
Plantarflexion
By Active contraction of soleus, with contribution from gastrocnemius
To maintain static posture, the internal moment of the knee is…
How?
flexion
Prevents knee hyperextension via…
Passive tension of posterior joint capsule and associated ligaments
Active contraction of: hamstrings & gastrocnemius
LOG passes slightly posterior to axis of hip
External moment:
extension
At times, postural sway may cause LOG to pass anterior and create flexion moment
To maintain static posture the internal moment at the hip is…
How?
flexion
Passive tension of hip ligaments
Active contraction of iliopsoas
LOG passes through the body of L5. external moment:
slight extension moment
Creates shear force rather than true torque
What opposes the external moment at L5 to maintain a static posture
Opposed by anterior longitudinal ligament, iliolumbar ligaments, facet joint approximation
LOG passes through external auditory meatus, anterior to axis for head
External moment:
Flexion of c-spine
To maintain a static posture at the head and neck, the internal moment is…
How?
extension of c-spine
Passive tension of ligamentum nuchae, tectorial membrane and posterior facet joint capsules
Active contraction of cervical extensors
When assessing standing posture in the posterior/anterior view, you are looking for
symmetry of the head, spine and feet
And
Scapulae lie flat on the thorax, Approximately between T2 and T7, and 4 inches apart
What is ideal posture of the knees in the anterior view
Patellae face directly forward
Slight physiological valgus
What is the ideal alignment of the ankles from the anterior view
Neutral (no supination or pronation)
What is the ideal alignment of the feet from the anterior view
Heels separated about 3 inches
Out toeing 8-10 deg
