2. DEFINITION
Posture can be defined as the
relative arrangement of
different parts of the body with
line of gravity.
Each structure contributes to
equilibrium and stability of body
in optimal standing position.
3.
4. TYPES OF POSTURE
Humans have the ability to arrange and
rearrange body segments to form a large variety
of postures. ( Erect bipedal stance )
STATIC POSTURE :
The body and its segments are aligned and
maintained in certain positions.
Examples : standing, sitting, lying, and kneeling.
DYNAMIC POSTURE :
postures in which the body or its segments are
moving
Examples : walking, running, jumping, throwing,
and lifting.
5. POSTURAL CONTROL
It is the persons ability to maintain-stability of
body and body segments in response to forces that
disturb the body’s structural equilibrium
Postural control depends on integrity of CNS,
visual, vestibular, and musculoskeletal system.
It also depends on information from receptors
located in and around joints and from sole of foot.
Reactive responses –reactions to external that
displaces body COM
Proactive response—internally generated
destabilizing forces
Example :rising arms to catch a ball
6. MAJOR GOAL AND BASIC ELEMENTS OF
CONTROL
Major goals :
Control body’s orientation in space
Maintain body’s COG and BOS
Stabilize the head vertically –eye gaze is
appropriately oriented
Elements of control :
CNS is able to detect instability and respond to
the input with appropriate output to maintain
equilibrium of body.
Musculoskeletal system have ROM for
responding to specific tasks
Muscles able to respond with appropriate
speed and forces.
7. ABSENT OR ALTERED INPUTS :
o When inputs are altered , control
system respond to incomplete data and
posture may be altered .
Example : foot “FALLEN ASLEEP”.
ALTERED OUT PUTS :
o Inability of muscles to respond to appropriately
to signals from CNS.
o Example : sedentary elderly persons .
8. MUSCLE SYNERGIES
“PERTURBATION” is any sudden change in
conditions that displaces the body posture
away from equilibrium .
perturbation
SENSORY MECHANICAL
(Altering of visual (displacements-movements
input) of body segment or entire
body [COM to BOS ])
Postural response to perturbations caused by
either platform or by pushes or pulls are called
REACTIVE or COMPENSATORY response.
9. SYNERGIES
Fixed support synergies
Change in support synergies
Head supporting strategies
The postural responses are called SYNERGIES
or STRATEGIES
10. FIXED SUPPORT SYNERGIES:
Pattern of muscle activity in which the BOS
remains fixed during the perturbation and
recovery of equilibrium.
Stability is regained through movements of
parts of the body but ,the feet remains fixed
on BOS.
EXAMPLES: Ankle synergy ,Hip synergy
ANKLE SYNERGY:
It consists of discrete bursts of muscle activity
on either the anterior or posterior aspects of
the body that occur in response to forward and
backward movements of the supporting
platform .
Muscle activity from distal to proximal pattern.
11. ANKLE SYNERGY
Anterior (forward)
movement of platform
Posterior (backward)
movement of body---
displacement of body’s
LOG posterior to BOS.
Activation of dorsiflexors,
hip flexors, abdominal
muscles, neck flexors
LOG back over BOS
STABILITY
12. ANTERIOR PERTURBATION
Posterior movement of
platform
Anterior movement of
body----displacement
of body’s LOG anterior
over BOS
Activation of plantar
flexors ,hip extensors
, back and neck
extensors
LOG back over BOS --
---STABILITY
13. HIP SYNERGY
It consists discrete bursts of muscle activity
in a proximal-to-distal pattern of activation.
Fixed-support hip synergy may be used
primarily in situations in which change-in-
support strategies (stepping or grasping
synergies) are not possible
14. CHANGE-IN-SUPPORT SYNERGIES
Strategies include stepping
(forward, backward, or
sidewise) and grasping (using
one’s hands to grab a bar or
other fixed support) in response
to movements of the platform.
Maintains stability in instance
of large perturbations.
Tether-release system.
Backward movement of platform,
person uses steeping strategy to
keep from falling forward .it brings
body’s COM over a new BOS.
15. HEAD STABILIZING STRATEGIES
Proactive strategy occur in anticipation of
initiation of internally generated forces caused by
change in position from sitting to standing.
Used in dynamic equilibrium situation.
Example : maintain head during walking.
Vertical stability of head is maintained by two
types of strategies
HEAD STABILIZATION IN SPACE (HSS):
Modification of head position in anticipation of
displacements of body COG.
HEAD STABILIZATION ON TRUNK (HST):
Head and trunk move as a single unit.
16. KINETICS AND KINEMATICS OF POSTURE
In response to perturbations, active internal
forces employed to counteract the external forces
that affect the equilibrium and stability of the
body in the erect standing posture.
External forces : Inertia, Gravity and ground
reaction forces (GRF’S)
Internal forces : Muscle activity, passive tension
in ligaments, tendons, joint capsules and other
soft tissue structures .
INERTIA: In erect standing posture body undergoes
a constant swaying motion called postural sway
or way envelop (4inches b/w feet—12 in sagittal
plane ,16 in frontal plane)
GRAVITY: Forces acts downward from body’s COG
(LOG falls within BOS)
17. GROUND REACTION FORCES :
When ever body contacts the ground , the ground
pushes back on body (GRF )
Vector representing it is called GRFV.
GRF have 3 component forces
1 vertical component force
2 horizontal component forces
- Medial and lateral direction
- Anterior and posterior direction
GRFV is equal in magnitude but opposite in direction
to GF in erect standing posture
The point of application of GRFV is at body’s centre of
pressure (COP)
COP is located in foot in unilateral stance and b/w feet
in bilateral stance.
18. COINCIDENT ACTION LINES :
GRFV and LOG have coincident action lines
in static erect posture.
It help to analysis of effect of these forces
on body segments.
External and Internal movements:
LOG passes at a distance from axis, an
external gravitational moment is created
and it causes rotation of superimposed
body segments around that joint axis
unless it opposed by counterbalancing
internal moment (muscle contraction).
19. OPTIMAL POSTURE
An ideal posture is one in which the body segments are
aligned vertically and LOG passes through all the joint
axes
Normal body structures makes it impossible to achieve,
but is possible to attain a posture, close to ideal one
In normal standing posture ,the LOG falls close to, but
not through most jt. axes -Compressive forces are
distributed over the weight bearing surfaces of joints; no
excessive tension exerted on ligamentous or required
muscles
Analysis of Posture from side view:
Analysis of posture involves identification of the location of
body segments relative to the LOG
Body segments-either side of LOG- symmetrical
A plumb line is used to represent the LOG
Postural analysis may be performed using; Radiography,
photography, EMG, electro goniometry, force plates, 3-
dimensional computer analysis
21. ANALYSIS OF KNEE IN SIDE VIEW
KNEE :
LOG passes anterior to midline of knee and posterior to patella.
22. HIP AND PELVIS ANALYSIS IN SIDE VIEW
LOG passes slightly posterior to axis of hip joint, through
greater trochanter leads to posterior pelvic tilt on femoral
head.
25. ANALYSIS OF
VERTEBRAL COLUMN
Optimal position of plum line
through midline of trunk.
At cervical- LOG posterior,
extension
At thoracic- LOG anterior,
flexion
At lumbar- LOG posterior,
extension
27. Deviations from optimal alignment
view from side
Foot and Toes:- Claw toes
Hammer toes
Knee:- Flexed Knee Posture -Genu Recurvatum
Pelvis:-Excessive Anterior Pelvic Tilt
Excessive posterior pelvic tilt
Vertebral column:- Lordosis
Kyphosis
Head:- Forward Head Posture
28. CLAW TOES :
Hyperextension of MTP joint, flexion of PIP and DIP joints.
Callus (thickening of epidermis )Formation on dorsal aspect of
flexed phalanges. Affects all toes (2nd through 5th)
Hammer Toe :
Deformity-hyperextension of MTP and DIP joints - flexion of PIP
joint.
Callus on superior surface of PIP joints
29. FLEXED KNEE POSTURE
This stance is maintained by
increased activity by
quadriceps, gastrocnemius,
soleus, and hip extensors
30. GENU RECURVATUM
The hyper extended knee
posture, LOG locates anteriorly,
puts the posterior joint capsule
under tension stress and
lengthening of posterior capsule,
cruciate ligament.
Anterior compression leads to
degenerative changes of
cartilaginous joint surface.
31. PELVIS
Excessive Anterior Pelvic
Tilt
Excessive Posterior
Pelvic Tilt
Straightening of lumbar
spine and loss of
flexibility and also loss
its ability to withstand
high load.
32. VERTEBRAL COLUMN
Kyphosis: It refers to an abnormal
increase in the normal posterior
convexity of the thoracic vertebral
column.
Two types :
Gibbus Hump Back is a deformity that
may occur as result of TB. It forms a
sharp posterior angulation in the upper
thoracic region of vertebral column
Dowager’s Hump is found in post-
menopausal women with osteoporosis.
Anterior aspect of bodies of series of
vertebra collapse due to osteoporotic
weakening and therefore, increase in
posterior convexity of thoracic area
Lordosis: It refers to an abnormal
increase in the normal anterior
convexities of either the cervical or
lumbar regions of the vertebral column
33. HEAD
Forward head posture :
Anterior location LOG ,increases flexion
movement this leads to increase constant
isometric muscle tension to support forward
head posture
Compression of posterior zygapophyseal joints
and posterior intervertebral disc and
narrowing of intervertebral foramen in
lordotic areas of cervical region.
38. PES PLANUS (FLAT FOOT )
Reduced or absent MEDIAL LONGITUDINAL ARCH,
which may be either rigid or flexible
Talar head-displaced-anterior, medial, inferior
and causes depression of navicular bone and
plantar calcaneonavicular (spring) ligament, and
lengthening of tibialis posterior muscle
Navicular lies below the Feiss line and may even
rest on the floor in severe conditions
39. RIGID FLAT FOOT
It is a structural deformity where the medial
longitudinal arch of foot is absent in NWB,WB
and toe standing
The arch is reduced during normal weight
bearing, but reappears during toe standing and
non weight bearing
FLEXIBLE FLAT FOOT
40. PES CAVUS
The medial longitudinal arch of foot may be
unusually high
A high arch is called pes cavus
It is a more stable position of foot than pes
planus
Weight borne on lateral borders of foot
Lateral ligament and peroneus longus
muscle stretched
41. KNEES
GENU VALGUM (Knock knees)
Mechanical axes of lower extremities are
displaced laterally and patella may be
displaced laterally
If genu valgum exceeds 30° (50 to 70 ) persists
beyond 8yrs of age – structural changes occur
Medial knee joint structures – abnormal
tensile or distraction stress
Lateral knee joint Structures – abnormal
compressive stress
42. GENU VARUM (Bow legs )
Knees are widely separated when the feet
are together and malleoli touches.
Cortical thickening on medial concavity –
on femur and tibia due to increased
compressive force
Patella may be displaced medially
Causes—vit D deficiency, renal rickets ,
osteochondritis.
44. Idiopathic scoliosis are categorized by age
infantile (0 to 3yrs ),
juvenile (4 to 10yrs),
adolescent (older than 10yrs)
45.
46. ANALYSIS OF SITTING
POSTURES
Sitting postures are more complex than
standing postures.
The same gravitational moments as in
standing posture must be considered,
The contact forces that are created when
various portions of the body interface with
various parts of chairs, such as head, back,
and foot rests, and seats.
48. MUSCLE ACTIVITY IN SITTING
POSTURES
Static erect posture: LOG close to joint axis in head
and spine
Slumped posture : LOG passes anterior to joint axis
Slouched posture : LOG passes posterior to joint axis
Flexion relaxation phenomenon helps to less muscle
activity in slouched posture than active erect sitting.
Muscles activity help in sitting posture-superficial
lumbar multifidus, thoracic erector spinae, internal
oblique abdominal muscles
49. Intervertebral disc pressure and
compressive loads on spine
IVD pressure is measured by creep phenomenon
Compressive force by calculating muscle activity
with electromyography
Flexed sitting posture is more harmful than
extend sitting posture
Because in kyphosis sitting increased
intervertebral disc shear force
Posterior annulus tensile force and anterior
anulus load, hydrostatic force in nucleus and
load on posterior ligaments
50. Seat interface pressures
Contact forces between persons body and seat are called seat
interface pressure
Measured by sensory-containing mats
Force per unit are measured by pascals
Individuals with physical disabilities (paraplegia), thin elderly
persons have higher pressure
Wheel-chair users have high tension, compression, shear forces
in gluteus muscles
Less muscle thickness under ischial tuberosity in elders
These measurements help to prevent pressure sores
To reduce seat interface pressure
Change the posture of body-forward and lateral trunk flexion
Alteration in angulation of chairs back rest
Using cushions (synthetic material, water, air, gel)reduces stress
Cushion thickness should be up to 8cm is useful
51. ANALYSIS OF LYING POSTURE
Interdiscal pressures are less in lying posture
than in standing and sitting postures.
Interdiscal pressures in supine lying (0.10 mpA)
were less than in either lying prone (0.11 mpA)
or lying on the side (0.12 mpA).
Some pressure-reducing mattress surfaces
include foam, air, gas, water and gel.
Other pressure-relieving surfaces include
movable surfaces, usually powered by a motor
or pump, which can alternatively inflate and
deflate.