Ideal Posture

The LoG pass through posterior part of cervical body vertebrae, anterior to thoracic vertebrae, crossing the center of the body of the fifth lumbar vertebra, close to the axis of rotation of the lumbosacral joint, slightly in front of the knee joint axis and finishing at the front of lateral malleolus.

Sagital plane

occur anterior and posterior postural sway

frontal plane (coronal plane)

occur medial and lateral postural sway

medial and lateral postural sway

can be counteracted by standing with the feet in the right position.

standing posture

structural adaptation, passive soft tissue tension and very little muscle activity are needed,

lumbar region

where passive soft tissue tension appears to be sufficient during passive standing

postural sway

is a learned behavior and is greater in childrens and old people

structural adaptation

because of this bonny structures create lordosis at spine and valgus angle at femur in order to minimize muscle activity during standing posture

LoG at lumbar region

creates the tendency for anterior displacement of L5 and of anterior rotation of the sacrum

resist anterior displacement of lumbar and sacral area

anterior longitudinal, iliolumbar, sacrospinous, sacrotuberous ligaments and the lumbosacral zygapophyseal joints

During passive standing of lumbar region

muscles like longissimus, rotatores, and neck extensors are active, but not too much

thoracic region

vertebrae of this region receive the greatest stress due to the LoG

postural sway

can be up to 12-16 degrees of movement is possible in sagittal and frontal planes

forward sway @ankle strategy during normal standing

counteract by paraspinals, hamstring, gastrocnemius

forward sway @hip strategy during normal standing

counteract by abdominals and quadriceps

backward sway @ankle strategy during normal standing

counteract by abdominals, quadriceps, dorsiflexor (tibialis anterior)

backward sway @hip strategy during normal standing

counteract by paraspinals and hamstring

ankle during neutral standing posture

His joint is midway between dorsiflexion and planterflexion and the line of gravity passes just anterior to him

soleus muscle

is necessary to pull the tibia posteriorly and generate a plantarflexion moment during standing

knee joint

when is fully extended the line of gravity passes anteriorly

knee joint LoG

create external extension moment and passive tension of the posterior joint capsule and ligaments usually counteract this to prevent hyperextension, hamstring also contribute.

In Hip neutral position the ASIS

is vertically aligned to the pubic symphysis and horizontally with the PSIS

Hip LoG during neutral stand (no movement occurring)

pass lightly posterior to his axis and through the greater trochanter

Hip LoG

during postural sway it may pass anterior and require muscular contraction of the iliopsoas

posterior tilt of pelvis

prevented by iliofemoral, pubofemoral, and ischiofemoral ligaments and also prevent hyperextension

During neutral position the LoG of head

create flexion moment and tend to tilt the head forwards

LoG of head

passes anterior to his axis

anterior tilt of the head

is counteracted by passive tensionn in the ligamentum nuchae, tectorial membrane, and zygapophyseal joints and by contraction of the neck extensors

knee region

No ligaments are able to counteract the effect of the LoG who pass anteriorly

moment act at the pelvis can be compensated/counterarct by

back extensors, hip (iliofemoral, pubofemoral, ischiofemoral) and lumbosacral ligaments (iliolumbar, iliosacral)

The moment act of the pelvis during standing is

anterior rotation

Spondilolysthesis

pathological condition created by the moment acting of the lower back and pelvis structures

pregnancy

Non pathological condition that result in increased curve at cervical and lumbar area, protraction of shoulder girdle and hyperextended knee

Hip structures counteracting hyperlordosis

excessive anterior tilt of pelvis causing ligamentous laxity and tension of paraspinal muscles

Hip structures counteracting hypolordosis

excessive posterior tilt of pelvis causing tension at ligaments and laxity of paraspinal muscles

Forward Head

pathological condition that result by the moment acting of the head during standing

thoracic region

LoG pass anteriorly with tendency to create hyperkyphosis

flat back posture (thoracic and lumbar)

result in decrease of the cervical curvature and posterior tilt of the hip

lumbar hyperlordosis and being seated with flexed legs at 90 degrees and erected back

result in anterior tilt of the hip

military back hyperkyphosis

result in increase of the lumbar curvature and anterior tilt of the hip

forward head

result in posterior tilt of the hip

genu valgum

due to knock knees tend to pronate the foot, increasing dorsiflexion functions, in order to compensate need to active plantarflexors muscles

genu varum

has increase in medial-lateral sway

genu valgum compensation

activate adductor of the hip, foot supinators , lateral muscles of the thigh are tensed, abductors gluteal muscles and medial ligaments are laxed

genu varum compensation

activate Abductor of the hip, foot pronators, medial muscles of the thigh are tensed, including those that insert at pes anserinus and lateral ligaments are laxed

genu varum

due to the bowed legs tends to supinate the foot, increasing plantarflexor functions, in order to compensate need to active dorsiflexors muscles

active erecting sitting

require high muscular activation and result in anterior tilt of the hip, increased pressure at IVD and decreased lumbar curvature

slouching/lean back sitting

require lower muscle activation and result in posterior tilt of the hip and decreased pressure at IVD

other postures that decreased pressure at IVD (not including slouching)

lying down at one side, supinated and pronated at bed

postures that increase pressure at IVD (not including active erect sitting)

being seated in the front part of a chair with muscle back relaxed (not using the backrest) and if you are holding something at the sides in the same posture is worst.

total control of posture

dominated from 7-10 years old

increased postural sway

can be seen in 6 years old children's and younger due to slower CNS responses and lack of muscle control

Flat Foot (Pes Planus)

result in lumbar hyperlordosis and anterior tilt of the pelvis

CNS (central nervous system)

control posture via feedback from proprioceptive systems in the muscles, tendons, and joints as well as passive biomechanical information

reactive response

compensatory mechanisim to maintain posture

proactive responses

anticipatory mechanism to maintain posture

proactive responses

stabilization of the head and eyes

reactive response

require muscle activation during forward and backward perturbation

backward perturbation compensation

ankle synergist are hip extensors, knee flexors and plantarflexors muscles hip synergist are neck extensors and paraspinals muscles

forward perturbation compensation

Ankle synergist are knee extensors, hip flexors and dorsiflexors muscles hip synergist are neck flexors and abdominals muscles

backward perturbation

reactive response that move the body anteriorly with the feet fixed on the base of support

foward perturbation

reactive response that move the body posteriorly with the feet fixed on the base of support

trip and fall

reactive response do not occur or was to slow, also can be due to bad or no muscular control

CNS input

can be affected by injuries and numbness of body parts

CNS output

can be affected by inability control muscles

if external forces increases

the distance between the line of gravity and the joint axis also increases

backward perturbation example

flexion-extension moments at the ankle axis. Because tibia moves anteriorly relative to the foot and cause dorsiflexion moment, requiring a plantarflexion moment of equal magnitude to re-establish equilibrium.

flexion relaxation phenomenon

thoracic extensors become completely inactive

First Stance phase - Double support I

when the heel of the interested leg is touching the ground as well the other leg touch the ground creating double support.

stance Double support I

include heel strike/initial contact and loading response

Second Stance phase - single support

include mid stance and terminal stance

third Stance phase - double support II

last phase that include pre-swing and toe-off

initial contact phase

where maximum knee extension and dorsiflexion occurs

terminal stance phase/ heel off

where Maximum knee extension just before heel off

pre swing phase/ toe off

where maximum plantarflexion occurs at toe-off

Foot weight transferring

from the heel, along the lateral side of the foot, crossing the metatarsophalangeal joints and ended at the big toe.

early stance

The ankle everts from 5 degrees inversion to 5 degrees of eversion

during toe-off/push-off.

the ankle tend to invert

loading response phase

where Maximum hip flexion occur

pre swing phase

where Maximum hip extension occurs at the midpoint between heel-off and toe-off

Swing phase

the leg of interest does not touch the ground and weight is being carried on the secondary leg

concentric muscles

they contract with tension to generate force for limbs movements and overcome loads

eccentric muscles

they just maintain stability, do not contract with tension and do not overcome loads