Download DynatomyChapter 8 File

Chapter 8
Fundamentals of Posture
Posture
• Posture is the alignment of the body and its
parts to accomplish action goal.
• Balance is the maintenance of postural
equilibrium = Postural Control (context
dependent)
• Postural Sway is movements with purpose to
maintain balance
• Static & Dynamic
Static Posture
• Static = involves little movement
– Steady State postures
• Standing Posture
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Head – erect position
Body weight on two feet
Bilateral structures, same level-iliac
Line of gravity
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Cervical
Thoracic
Lumbar
Hip
Knee
Ankle
Posterior Anterior +
Posterior Posterior Anterior +
Anterior +
– Spinal curvatures
Standing Postures
Asymmetric Posture – Weight
shift to one leg, with knee fully
extended. Anterior LOG to knee
creates extensor moment,
reduces quad. Activation.
Nilotic Stance – One legged
stance, with opposite leg
supporting behind the knee.
Normal Alignment
Sitting Posture
• Correct sitting posture – always varies, by
definition it is one that reduces stress/strain to any
one specific region.
Lying Posture
Surfaces
• Hard
• Soft
• Normal
Dynamic Posture
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Walking
Running
Jumping
Throwing
Kicking
Types of Postural Control
• Static PC – COG or LOG within base of
support.
• Reactive PC – Unexpected shifts to LOG,
slipping or tripping, LOG is within BOS.
• Anticipatory PC – Adjusting BOS to resist
oncoming forces.
• Adaptive PC – Context dependent
Sensors
• Proprioceptors
– Muscle Spindle
– Golgi Tendon Organ
– Joint Receptors
– Vestibular Apparatus
• Exteroceptors
– The … senses
Mechanisms of Postural Control
Postural Alterations and Pertubations
• Changes in postures caused by
physiologic, psychological, environmental,
anatomic or developmental factors.
– Can also be task dependent variations or
repeated disturbances(perturbations)
Developmental
Considerations
• Perception-Action Coupling
– Respond to environmental cues
• Motor Milestones
• Bayley Scales of Infant Development
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Head erect 1.6
Sitting slight support 2.3
Sitting alone momentarily 5.3
Rolling back-front 6.4
Sitting alone 6.6
Pulling-stand 8.1
Standing up support 8.6
Stepping 8.8
Standing 11
Walking 11.7
Walking backwards 14.6
Walking up stairs 16.1
Jumping 23.4
Postural reactions in infants
Older Adults
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Postural changes
Declines in vision
Loss of vestibular function
Muscle loss
Increased sway
Impairment of sensory info
Slower response/reaction times
Decreased ROM
Disc issues/pain
Postural Dysfunction
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Pain
Decreased ROM
Muscle loss/imbalances
Joint laxity/hypermobility
Proprioceptive dysfunction
Psyche, environment, defects, fatigue, etc
Anatomic changes(pregnancy)/defects
Habituation
Locomotion: Walking - Gait
• Locomotion is the act of moving from place to
place
• Gait is particular form of locomotion
– Walking
– Running
Walking Gait Cycle
• Gait Cycle refers to sequential occurrence
of stance and swing phase for a single limb
– Stance Phase --- foot contacts ground
– Swing Phase --- leg moving forward
• Stride period from initial contact of one leg
till the next initial contact of the same leg
• One stride is two steps
• Double Support
• Single support
• Cadence is the step rate = steps / minute
– Velocity = step length * cadence
– Velocity = stride length * stride frequency
Gait Analysis I
Levangie & Norkin (2001)
Gait Analysis II
According to Perry
Temporal and Spatial Characteristics
• Normal Walking versus Fast Walking
Gait Characteristics
• Female & Male
– Step length 14%
– stride length1.28 to 1.46
– Step width 7 to 9
• 7o direction of
progression
• 3 mph (1.34m/s)
• Younger & Older
• Velocity differences
• Increase support phase
Muscle Activity and Control
• Initial Contact and loading response
– Hip abductors ecc prevent lateral tilt, knee ext ecc, ankle
dorsiflexors ecc
• Mid-stance
– Plantar flexors ecc control tibia, gastro helps stabilize knee
• Terminal Stance
– Plantar flexors for push-off
• Pre-swing
– Hip flexors ( …, gracilis, sartorius)
• Initial Swing and midswing
– Ankle Dorsiflexors ( …extensor hallucis longus, extensor
digitorum longus, peroneus tertius)
• Late Swing and Terminal Swing
– Ankle Dorsiflexors ecc, knee ext ecc, hamstrings
Life Span perspective
• Infants
– Crawling
– Creeping
• Gait Characteristics
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Stride Length increase
Flat-foot to heel strike
Reduced out-toeing
Narrow base to anterior-posterior emphasis
Knee-extension at Heel Contact & Knee Flexion Midstance
Pelvis Rotation
Improved Balance reduction in forward inclination
Coordination of hands (Contra-lateral)
• Older Adults
• Trendelenberg gait – paralysis of hip Abductors
• ACL-deficient knee – quadriceps avoidance
• Cerebral Palsy – muscle dysfunction and paralysis
– Spastic Diplegia
• Equinus of foot