Lecture 7 - Posture and Gait Flashcards by Chance Lee Cauble

POSTURE

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What is the difference between static and dynamic posture?

Static
-Body and its segments are aligned and maintained in a specific position
Dynamic
-Body and its segments are moving

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What are some examples of dynamic posture?

walking
running
squating

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How is dynamic posture different from motion analysis?

Dynamic posture is describing a point during a movement (such as bottom of squat) while motion analysis analyzes entire movement of a squat.

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What is meant by the base of support (BoS)?

Area bounded posteriorly by the tips of the heels and anteriorly by a line jointing the tips of the toes.

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What does center of gravity (CoG) mean?

point where gravity is equally distributed

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What does center of mass (CoM) mean?

point where mass of the body is centered

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Where does normal center of mass lie on humans?

anterior to S1/S2

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When do we see instability in regards to our CoM?

when our CoM falls outside our base of support (BoS)

- CoM should be centered over BoS

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The _______ the BoS and the ______ the CoG, the harder it is to get off balance.

wider

- lower

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Using an assistive device __________ the size of an individual’s BoS, providing for more ___________.

increases

-postural support

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Postural Control involves maintenance of ______________ over ___________ to control body’s orientation in space and stabilize _____ with respect to vertical to orient gaze

center of mass (CoM)
base of support (BoS)
head

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Postural control requires CNS control, what are the afferent inputs and efferent outputs involved?

Afferent
-somatosensory
-vestibular
-visual
Efferent
-muscular contraction

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Responses that occur as reactions to EXTERNAL FORCES that displace the bodies CoM is called what?

Reactive (compensatory) responses

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Responses that occur in anticipation of INTERNALLY generated destabilizing forces is called what?

Proactive (anticipatory) responses

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What is an example of reactive response?

-taking a step to keep balance as bus moves

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What is an example of proactive response?

raising arms to catch ball

- bending forward to tie shoe

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What is postural sway?

normal small oscillations in which the body sways anteriorly, posteriorly, and side to side

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What is a normal postural sway during quiet stance?

up to 7mm

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What is one way to determine postural sway?

Mapping the center of pressure through the feet

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Increased postural sway = ____________

Why?

increased fall risk

- CoM nearing or leaving BoS

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What are some examples of health conditions that can lead to increased postural sway?

Hemiparesis
Sensory deficits
Flat and high-arched feet
Vestibular dysfunction

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Posture may be altered and stability may be compromised with __________ or ________ inputs.

altered or absent

-ie. decreased sensation of the LE or post-injury

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Alterations in ________ also comprimise posture

outputs

-ie. inability of muscles to respond appropriately to signals from CNS due to a neuromuscular disorder

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Maintenance of standing posture is the result of ________ controls

dynamic

A normal functioning CNS selects the most appropriate combo of muscles to complete the task at hand after analyzing __________.

sensory input

What is perturbation?

Sudden change in condition that displaces body away from equilibrium

What are the 3 components of sensory perturbation?

- somatosensory - visual - vestibular

What is mechanical perturbation?

displacement causing changes in the relationship of the body’s CoM to BoS

What are the 2 main muscular strategies for postural stability?

- Ankle Strategy | - Hip Strategy

Ankle Strategy -Discrete bursts of muscle activity that occur in a ________ to _______ pattern. Hip Strategy -Discrete bursts of muscle activity that occur in a ________ to _______ pattern.

- distal to proximal | - proximal to distal

What strategy is typically utilized first, ankle or hip?

ankle

Ankle strategy is better for _______ perturbations and ________ losses of postural equilibrium.

- smaller | - smaller

Hip strategy is better for _______ perturbations and ________ losses of postural equilibrium.

- larger | - larger

Both ankle and hip strategies are examples of fixed support strategies. What does this mean?

Feet remain fixed while stability is regained through movements of the body without having to take a step.

What are the muscles that are activated for forward sway in both ankle and hip strategy? List order of activation as well.

Ankle 1. ) gastrocnemius 2. ) hamstrings 3. ) paraspinals Hip 1. ) abdominals 2. ) quadriceps

What are the muscles that are activated for backward sway in both ankle and hip strategy? List order of activation as well.

Ankle 1. ) tibialis anterior 2. ) quadriceps 3. ) abdominals Hip 1. ) paraspinals 2. ) hamstrings

What are the 2 strategies that are used when equilibrium has to be obtained by moving?

- Stepping Strategies | - Grasping Strategies

Both stepping and grasping strategies move or enlarge the body's _____ so that it remains under the ____. These strategies are successful with a ________ perturbation.

- BoS - CoM - large

What is the difference between older and younger patients in regards to stepping strategies?

Younger individuals usually only take 1 step whereas older individuals more commonly take multiple shorter steps

Muscle strategies are examples of ______ forces to counteract _______ forces affecting our equilibrium.

- internal | - external

What is equilibrium in regards to internal and external forces?

sum of internal and external forces = 0

What is the Ground Reaction Force Vector (GRFV)?

Force of the ground pushing back on the body in standing

What is the Line of Gravity (LoG)?

Line extending from center of gravity to the base of support

If we are standing in quiet stance the GRFV matches what?

Line of Gravity (LoG)

What is the Center of Pressure and where is it usually located?

- point of application of the GRFV | - located between the feet in bilateral stance

The further the Line of Gravity (LoG) is from a joint axis, the ____ movement we get at that joint. What is needed to counteract this?

- more | - internal moment of muscle contraction

The magnitude of the external moment ________ as the distance between the LoG and joint axis increases.

increases

If LoG is anterior to joint axis, external moment will cause anterior motion of the _________ segment supported by that joint.

proximal

What are the internal moments that must occur at each section if the GRFV passes posterior to the ankle, anterior to the knee, and anterior to the hip?

Ankle -internal dorsiflexor moment to counteract external plantarflexor moment Knee -internal flexor moment to counteract external extensor moment Hip -internal extensor moment to counteract external flexor moment

What is a postural assessment?

systematic observation of a patient, paying special attention to deviations from the norm

What are the goals of a 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

What are the keys to success of a postural assessment?

- Assess from multiple angles - Remove obstructive clothing - Observe more than the area of complaint

In an ideal standing posture side view the LoG passes through or very close to all joint axes. What does this minimize?

- minimizes external moments | - balanced by internal moments

Large deviations of LoG passing through the body results in: - excessive strain on ________ structures - _______ muscular activity

- passive | - increased

Long-term deviation results in _________ changes.

structural

What are the ideal alignment placed of the LoG from the ground up? *Most Important Ones*

- Slightly anterior to the lateral malleolus - Slightly anterior to the axis of the knee joint - Slightly posterior to the center of the hip joint - Midway through the shoulder - Through the external auditory meatus

Ideal Posture: Ankle - LoG passes slightly _______ to lateral malleolus - External moment = __________ - Internal moment = _________ - Active contraction of ________, with contribution from ____________

- anterior - dorsiflexion - plantarflexion - soleus, gastrocnemius

Ideal Posture: Knee - LoG passes ________ to midline of the knee and __________ to patella - External moment = __________ - Internal moment = ____________ - The internal moment prevents knee hyperextension via passive tension of ________ joint capsule and associated ligaments as well as active contraction of ___________ and ___________.

- anterior, posterior - extension - flexion - posterior, hamstrings and gastrocnemius

Ideal Posture: Hip - LoG passes slightly _________ to axis of hip - External moment = _________ - Internal moment = _________ - Passive tension of hip ligaments and active contraction of _________.

- posterior - extension - flexion - iliopsoas

Ideal Posture: Lumbosacral Joint - LoG passes through the body of ___ causing slight _________ moment. - Lumbosacral angle is about ___ degrees, increased anterior pelvic tilt would ________ lumbosacral angle. - Creates ____ force rather than true torque that is opposed by ALL, iliolumbar ligaments, and facet joint approximation.

- L5, extension - 30, increase - shear

Ideal Posture: Head and Neck - LoG passes through _________________ - External moment = ___________ - Internal moment = ___________ - Internal moment occurs from passive tension of ligamentum nuchae, tectorial membrane and posterior facet joint capsules as well as active contraction of _______________.

- external auditory meatus - flexion of cervical spine - extension of cervical spine - cervical extensors

Ideal Standing Posture: Posterior View - Looking for midline of head, spine, and evenly spaced feet - Can also assess shoulder and scapula. The scapula should be approximately between T_ and T_ and __ inches apart (give or take).

- T2 and T7 | - 4

Ideal Standing Posture: Anterior View - Patella face directly forward with a slight physiological _______. - Ankles are neither _________ or _________. - Heels seperated by about __ inches, out-toeing about _-_ degrees.

- valgus - supinated or pronated - 3 inches, 8-10 degrees

The shoulder of a patients dominant arm is often ______ than the shoulder of their non-dominant arm.

lower

GAIT

Stride is synonymous with a _________.

gait cycle

Step is a sequence of events that occurs within heel contacts of _________ feet. Therefore a gait cycle has ____ steps.

- opposite | - 2

What is the difference between a stride length and a step length?

Stride Length -distance between two successive heel contacts of the SAME foot Step Length -distance between successive heel contacts of 2 DIFFERENT feet

What is the normal stride length of males and females?

- Male = 1.51m | - Female = 1.32m

What is a normal degree of toe-out?

5-7 degrees

What is step width and what is the average?

- lateral distance between heel centers of 2 consecutive foot contacts - 7-10cm

Temporal Descriptors of Gait (Time) - What is stride time? - What is step time? - What is cadence?

- time for a full gait cycle - time for completion of a R or L step - number of steps/minute, also described as step rate

What is a normal cadence for males and females?

Males- 108 steps/min | Females- 118 steps/min

What is a spatitemporal descriptor a combination of?

spatial and temporal descriptors of gait

What is gait velocity and what is the normal for males and females?

- distance covered in a given amount of time - Males- 1.37m/sec ***** - Females- 1.30m/sec *****

What is the best and most functional measurement of individuals walking ability?

Gait Velocity

What are the 2 ways to increase gait velocity?

- increase step/stride length | - increase cadence

What is the "6th vital sign"?

Gait speed

How is the 10M Walk Test performed?

- 2m acceleration zone - 10m walk/timed section - 2m deceleration zone

At a normal walking speed, ___% of our time spent in stance phase with the other ___% being spent in swing phase.

- 60% | - 40%

Single-limb support account for ___% of the gait cycle with the other ___% being double-limb support.

- 80% | - 20%

Stance phase is the time from R ____ contact to R ___ off.

- heel | - toe

Rancho Los Amigos terminology breaks up stance and swing phase into additional phases. What are they?

STANCE - Initial contact - Loading response - Midstance - Terminal stance - Preswing SWING - Initial swing - Mid swing - Terminal swing

- Describe Initial Contact (IC). - What is the critical event? - What phase is the opposite limb in during initial contact?

- The instant the foot hits the ground. - heel first contact - terminal stance (TSt) / Preswing (PSw)

-What are the positions and major muscles of the hip, knee, and ankle during initial contact?

Hip - 20° flexion - extensors Knee - 0-5° flexion - quadriceps Ankle - 0° - pretibials

- Describe Loading Response (LR). - What are the critical events? - What phase is the opposite limb in during loading response?

- Shock is absorbed as forward momentum is preserved. A foot flat position is achieved. - hip stability, controlled knee flexion, and ankle PF - Preswing (PSw)

-What are the positions and major muscles of the hip, knee, and ankle during loading response?

Hip - 20° flexion - extensors, abductors Knee - 15° flexion - quadriceps Ankle - 5° PF - pretibials

When does Loading Response (LR) turn into midstance (MSt)?

As soon as the opposite foot leaves the floor

Initial contact (IC) and loading response (LR) combine for the functional goal of ______ acceptance, ______ absorption, and to provide a stable base for the body to progress over.

- weight | - shock

- Describe Midstance (MSt). - What is the critical event? - What phase is the opposite limb in during midstance?

- The body progresses over the foot in a controlled manner. First instance of single limb support. - controlled tibial advancement - midswing (MSw)

-What are the positions and major muscles of the hip, knee, and ankle during midstance?

Hip - 0° - abductors Knee - 5° flexion - quadriceps ->quiet Ankle - 5° DF - Gastroc-soleus

- Describe Terminal Stance (TSt). - What is the critical event? - What phase is the opposite limb in during terminal stance?

- Progression over the stance limb continues past the forefoot. Body is ahead of stance limb. - controlled ankle DF with heel rise - terminal swing (TSw)

-What are the positions and major muscles of the hip, knee, and ankle during terminal stance?

Hip - 20° extension - none Knee - 5° flexion - none Ankle - 10° DF - Gastroc-soleus

- Describe Pre-swing (PSw). - What are the critical events? - What phase is the opposite limb in during pre-swing?

- Rapid unloading of the limb with weight transfer to opposite limb, starting the second period of double limb support. - passive knee flexion to 40°, ankle PF, 60° MTP ext - initial contact (IC) -> loading response (LR)

-What are the positions and major muscles of the hip, knee, and ankle during pre-swing?

Hip - 10° extension - adductors Knee - 40° flexion - none Ankle - 15° PF - None -> Tib Ant

- Describe Initial Swing (ISw). - What are the critical events? - What phase is the opposite limb in during initial swing?

- The thigh begins to advance as the foot leaves the floor - hip flexion, knee flexion - loading response (LR) -> midstance (MSt)

-What are the positions and major muscles of the hip, knee, and ankle during initial swing?

Hip - 15° flexion - flexors Knee - 60° flexion - flexors Ankle - 5° PF - pretibials

- Describe Mid Swing (MSw). - What are the critical events? - What phase is the opposite limb in during mid swing?

- Thigh continues to advance, knee begins to extend as foot clearance is maintained. - continued hip flexion, foot clearance - midstance (MSt)

-What are the positions and major muscles of the hip, knee, and ankle during mid swing?

Hip - 25° flexion - flexors Knee - 25° flexion - flexors Ankle - 0° DF - pretibials

- Describe Terminal Swing (TSw). - What are the critical events? - What phase is the opposite limb in during terminal swing?

- The leg reaches out to achieve step length - knee extension - terminal stance(TSt)

-What are the positions and major muscles of the hip, knee, and ankle during terminal swing?

Hip - 20° flexion - extensors Knee - 5° flexion - quadriceps Ankle - 0° DF - pretibials

What are the 3 functional tasks of gait?

- Weight Acceptance - Single Limb Support - Swing Limb Advancement

- What are the phases involved in weight acceptance? | - What are the main goals in weight acceptance?

- initial contact (IC) - loading response (LR) -forward progression, stability, and shock absorption

- What are the phases involved in single limb support? | - What are the main goals in single limb support?

- mid stance (MSt) - terminal stance (TSt) -stability and forward progression

- What are the phases involved in swing limb advancement? | - What are the main goals in swing limb advancement?

- preswing (PSw) - initial swing (ISw) - mid swing (MSw) - terminal swing (TSw) -foot clearance and limb advancement