Posture & balance Flashcards
What is the difference between static & dynamic posture?
Static:
- body is aligned and maintained in certain positions (standing, sitting, kneeling)
Dynamic:
- body is moving (walking, running, lifting)
Explain the relationship between CoM, LoG, and BoS
- LoG must stay w/in BoS or individual will fall
- Higher CoM = LoG outside BoS = less stable
- Lower CoM = LoG stays inside BoS = more stable
Does CoM move towards or away from weight added?
- towards
How does reactive postural control differ from proactive postural control?
Reactive:
- compensatory
- “reacts” to the external forces
Proactive:
- anticipatory
- getting ready for the external forces
What are the 3 systems responsible for postural control?
- vestibular
- vision
- somatosensory (proprioceptors in joints, ligaments, tendons, muscles
What are the goals of control?
- control body’s spatial orientation
- keep CoM over BoS
- stabilize head vertically for gaze
Why is a person likely to re-sprain an ankle after the initial sprain injury?
- ankle lacks ability to detect PROM & less stable
- lack of input for proprioception
- can’t detect input = less ability to be reactive/proactive
What is an example of sensory perturbations?
- altering vision input
- closing eyes/ears w/ balance training
What is an example of mechanical perturbations?
- cause direct changes in CoM to BoS relationship
- arm locked in a position then external force pushing/pulling the arm
What are the anti-gravity postural muscles?
- Neck & back extensors (erector spinae)
- hip & knee extensors (glutes)
- Neck & trunk flexors (abdominals)
- hip abductors & adductors (TFL, glute med)
- DF’s & PF’s (gastroc/soleus, tib anterior)
Describe the type of postural synergy or strategy for the ankle, hip, and stepping when it comes to size of perturbation
Ankle:
- small
Hip:
- large
Stepping:
- very large
Describe the type of postural synergy or strategy for the ankle, hip, and stepping when it comes to order of muscle activation
Ankle:
- posterior displacement = tib ant., quads, abs
- anterior displacement = gastroc, hamstrings, para spinals
Hip:
- Posterior displacement = abs, quads, tib ant.
- Anterior displacement = para spinals, hamstrings, gastroc
Describe the type of postural synergy or strategy for the ankle, hip, and stepping when it comes to sequence of strategies with increasing perturbation
Ankle:
- distal to proximal
Hip:
- proximal to distal
Stepping:
- widens BoS
- younger take 1 step
- older take multiple
Describe the type of postural synergy or strategy for the ankle, hip, and stepping when it comes to typical scenarios for each strategy
Ankle:
- leaning forward/backward & keeping balance
Hip:
- balancing on a board/tightrope
Stepping:
- falling over & taking a step to catch yourself
What is postural sway?
- body’s constant swaying motion
- sagittal = 12 degrees
- frontal = 16 degrees
Limit of Stability (LoS) = edge of the sway envelope
How does the CoP relate to the LoG & GRF?
- CoP is the center where the force is put through a surface
- the closer the CoP, LoG, & GRF’s are to each other the more balanced an individual will be
- less sway will occur
Explain the difference between External and internal moments as it relates to posture
External:
- gravity; a moment increases as the LoG moves further away from the joint
Internal:
- muscles; counteract the gravitational moment which puts less stress on the joint
Describe where the LoG should fall from head to toe for optimal postural alignment
Frontal plane:
- through external auditory meatus (as close to the joints as possible to the ankle)
Sagittal plane:
- make 2 completely symmetric halves
What are the consequences of prolonged postural deviations, even small ones?
- body doesn’t recognize faulty postures as abnormal over time
- muscles shortening/lengthening = alters length-tension relationship
- ligament shortening = limits ROM
- ligament lengthening = unstable joints
- cartilage degeneration from improper weight bearing on joint surfaces
Discuss the consequences of flexed knee posture
- LoG moves to posterior to knee
- causes quads to produce an external force (fatigues too fast)
- fall risk
- patellofemoral joint stress
- causes hip extensors to produce an external force
- increases soleus activity to combat DF moment
Discuss the consequences of genu recurvatum
- knee hyperextension beyond neutral (LoG anterior)
- posterior capsule under a lot of tension
- unstable knee
- increases compression in anterior knee
- length-tension relationship altered which could affect muscles ability to change this
Discuss the consequences of anterior pelvic tilt
- lower lumbar vertebra move anterior
- upper lumbar vertebra move posterior
this increases lordosis in lumbar/cervical regions and kyphosis in thoracic region - increases compressive forces on annulus = less nutrition
- increases compression at facet joints
Discuss the consequences of posterior pelvic tilt
- spine flattens out = less flexibility
- decreases lumbar spine’s ability to withstand high loads
Discuss the consequences of thoracic kyphosis (exaggerated)
- increases compression on thoracic vertebral bodies
- LoG anterior = increases IMA
- posterior tensile stress increases
- decreases force generating capacity of back extensors
- soft tissue creep
Discuss the consequences of forward head posture
- facet & disc compression
- foraminal narrowing
- extensor ischemia
- facet capsules shortened
- nerve root compression
- TMJ altered
- scapular IR
- thoracic kyphosis
- decreased vital capacity
Explain proper sitting posture as if you were talking to a patient
- sitting upright, flatten your back, chest up tall
Why is proper sitting posture so important?
- decreases compression on discs & helps decrease the risk of altering length-tension relationship of muscles/ligaments
What is the best sitting position to decrease pressure on the intervertebral discs?
- seat reclines b/w 110-130
- lumbar support about 5cm from chair
- posterior seat inclined about 5 degrees
- arm rest help w/ reduction
What are the 4 types of sitting?
- active erect sitting
- relaxed erect sitting
- slumped sitting
- slouched sitting
How does pregnancy affect posture?
- CoM changes
- increased cervical & lumbar lordosis
- shoulder girdle protraction
- knee hyperextension
