Posture (WK14) Flashcards
What is the difference between static and dynamic posture?
static: when the body and it’s segments are distributed in a manner that the body remains in equilibrium. ( standing, sitting, lying)
dynamic: when the body or it’s segments are moving ( walking, running, throwing)
Explain the relationship between CoM, LoG, and BoS
CoM: the point at which mass is equally distributed
LoG: a vertical line descending vertically from your CoM
BoS: an area between all points of contact
if LoG falls outside BoS you may fall; a lower CoM increases stability
How does reactive postural control differ from proactive postural control ?
proactive postural control anticipates changes in posture and premptively contacts muscles to eliminate or diminish unwanted movement.
reactive simply contracts in response to an external force
Why is a person likely to resprain an ankle after the initial injury ?
due to injury to mechanoreceptors affecting propioceptive data going to the brain which would, under normal conditions, reflexively contract muscles to protect the ankle.
Give 1 example of a sensory perturbation and a mechanical perturbation
sensory: blindness
mechanical: external trauma or impact
Describe the following type of postural strategy: Ankle
small perturbations
posterior displacement: TA, quadriceps, abdominals
anterior displacement: gastroc, hamstrings, paraspinals
Describe the following type of postural strategy: Hip
larger perturbations
posterior displacement: abdominals, quadriceps, TA
anterior displacement: paraspinals, hamstrings, gastroc.
What is postural sway ?
The influence of gravity and inertia produce external forces or moments on the body which produces small imperceptible motion.
How does the CoP relate to the LoG and GRF ?
The CoP is a calculated point that gives an idea of the sum of all contact pressures; this would imply where the CoM is and thus the LoG as well as the GRF vector position.
Explain the difference between external and internal moments.
External moments are created when the LoG passes at a distance from the AoR. An internal moment must be created to counteract this motion.
Describe where the LoG should fall from head to toe for optimal postural alignment.
Head: anterior or directly through the external auditory meatus
Spine: anterior to concavity at each segment
Pelvis and Hip: anterior to S2
Knee: anterior to femoral condyle
Ankle: anterior to lateral malleolus
as close to joint axis as possible
What are the consequences of prolonged postural deviations, even small ones.
body does not recognize chronic faulty postures
-ligament and muscle shortening and lengthening
- loss of length tension relationships; limited ROM; unstable joints
- cartilage wear due to abnormal joint loading
Discuss consequences of the following major postural deviation: Flexed Knee Posture
-external flexion moment at knee and hip
- Increased quad force required leading to joint compression and increased soleus activity; prone to falls
- requires more energy
Discuss consequences of the following major postural deviation: Genu Recurvatum
- external extensor moment
- lengthening of cruciate and posterior ligaments of knee; anterior knee compression= degeneration; muscle force altered.
Discuss consequences of the following major postural deviation: Ant. Pelvic Tilt
increased lumbar lordosis; increased EMA= Increased extension moment; degeneration at facets; decreased nutrient supply at discs
