The document discusses the neurophysiology of posture and movement, covering topics such as types of posture, frameworks for postural control, and the roles of various systems including motor, sensory, and cognitive components. It highlights how postural control is maintained through mechanisms like muscle tone and reflexes, as well as the contributions of the vestibular system, visual pathways, and proprioception. The latter part presents research on postural control deficits in individuals with multiple sclerosis, showing significant challenges compared to healthy individuals.

1. NEUROPHYSIOLOGY BEHIND
POSTURE AND MOVEMENT
Vinodhini.CKV
Occupational Therapist

2. 2
Overview:
Posture
and types
Framework
of posture
Physiology
of posture
Motor
control of
posture
Visual
control of
posture
Vestibular
control of
posture
Research

3. Definitions:
▪ Postural control: involves controlling the body’s position in
space for the dual purposes of stability and orientation .
▪ Posture: describes the biomechanical alignment of the body and
the orientation of the body to the environment
▪ Postural stability: Is the ability to control the centre of mass in
relationship to the base of support.
3

4. Types of posture:
▪ Static posture
▪ The body and its segments are aligned and maintained in
certain positions
▪ Dynamic posture
▪ Refers to postures in which the body or its segments are
moving.
4

5. Framework for
postural control:
Musculoskeletal
Muscle synergies
Sensory
systems
Sensory
organization
Cognitive strategies
Cognitive rescoures
5
Individual
• Motor
• Sensory
• Cognitive
Environment
• Support
surfaces
• Sensory context
• Cognitive load
Postural
tasks
• Steady state
• Proactive
• Reactive

6. Types of postural tasks
▪ Steady state balance: Stability underlying sitting or standing
quietly has often been called as “static balance”
▪ Reactive balance control: movement strategies in response to
brief displacements of supporting surfaces
▪ Proactive(anticipatory) balance control: a preprogrammed
force based on anticipation of what the task requires based on
previous experiences by the CNS.
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7. 7
Feedforwardversus
feedbackpostural
control
Central
command Limb
movement
Postural
disturbances
Postural
adjustment
Feedforward:
for expected
postural
disturbances
Feedback: for
unexpected
postural
disturbances

8. Physiology behind postural control:
▪ Depends on
▪ –Motor/ somatosensory
▪ –Visual system
▪ –Vestibular system
8

9. Motor systems in postural control:
▪ Motor systems ensure the generation of coordination of
appropriate muscles to control the body’s position and
movement in space
▪ Motor systems include:
▪ Higher level planning: frontal and motor cortex
▪ Coordination: brainstem ,cerebellum and basal ganglia
▪ Generation of forces: motor neurons and muscles
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10. CORTICAL
AREAS INVOVED
IN MOTOR
CONTROL
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11. DESCENDING PATHWAYS FROM THE
MOTOR CORTEX
▪ Corticospinal Pathway/Pyramidal Tract
▪ Corticobulbar Pathway
▪ Extrapyramidal Pathway
▪ Cerebellum
▪ Basal ganglia
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12. Corticospinal tract:
▪ Pyramidal tracts of spinal cord are the descending tracts
concerned with voluntary motor activities of the body. These
tracts are otherwise known as corticospinal tracts.
▪ There are two corticospinal tracts, the anterior corticospinal tract
and lateral corticospinal tract.
12

13. 13
Corticospinaltract:

14. Corticobulbar pathway:
▪ Also known as corticonuclear tract
▪ Is a two neuron white matter motor pathway connecting motor
cortex in the cerebral cortex to the medullary pyramids
▪ Function: muscles of the face, head and neck are controlled by
the corticobulbar system
▪ It innervates cranial nerve v, vii, xi and xii
▪ Also innervates the motor part of cranial nerve x
14

15. 15

16. Role of Extrapyramidal pathway
▪ They adjust body posture to provide stable background for
movement.
▪ Concerned with grosser movements and posture
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17. Role of cerebellum
▪ Spinocerebellum regulates the postural reflexes by modifying
muscle tone .It facilitates the gamma motor neurons in the
spinal cord via cerebello-vestibulo-spinal neurons in the spinal
and
▪ Cerebello-reticulo-spinal tracts .The gamma motor neurons
reflexly modify the activity of alpha motor neurons and thus
regulate the muscle tone. Thus, cerebellum forms an important
site of linkage of alpha-gamma systems responsible for muscle
tone
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18. Role of basal ganglia:
▪ Basal ganglia are the scattered masses of gray matter
submerged in subcortical substance of cerebral hemisphere
▪ Basal ganglia include three primary components:
▪ 1. Corpus striatum (caudate and lenticular nucleus)
▪ 2. Substantia nigra
▪ 3. Subthalamic nucleus of Luys.
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19. BASAL GANGLIA
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20. Control of posture by basal ganglia:
▪ Basal ganglia control the muscle tone. In fact, gamma motor
neurons of spinal cord are responsible for development of tone
in the muscles
▪ Reflex muscular activities, particularly visual and labyrinthine
reflexes are important in maintaining the posture. Basal ganglia
are responsible for the coordination and integration of impulses
for these reflex activities.
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21. Role of brainstem:
▪ Red nucleus of the brainstem plays an important role in the
maintenance of posture.
▪ Red nucleus is a large oval or round mass of gray matter,
extending between the superior colliculus and hypothalamus.
▪ Pathways of red nucleus:
▪ The Ventromedial Pathway
▪ The Lateral Reticulospinal Tract
▪ The Rubrospinal Tract
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22. 22

23. The Ventromedial Pathway:
 Vestibulospinal tract:
▪ Carries information from vestibular nucleus for reflex control of
equilibrium
 Tectospinal tract:
▪ Originates in tectum for control of head and eye movements
 Medial reticulospinal tract:
▪ Originates in reticular formation for maintaining posture by
activation of extensors
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24. Lateral
reticulospinal
pathway
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▪ Originates in reticular formation for
maintaining posture by activation of
flexors

25. The rubrospinal pathway:
▪ The rubrospinal tract begins in the magnocellular red nucleus.
▪ The rubrospinal tract terminates in the cervical segments of the
spinal cord and therefore only innervates upper limbs. It is
believed that in humans it is responsible for arms swinging while
walking or baby crawling motion.
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26. Rubrospinal tract:
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27. Somatosensory factors that maintain posture:
▪ Dominant sensory
system
▪ Provides fast input
▪ Reports information
▪ – Self-to-(supporting)
surface
▪ – Relation of one
limb/segment to another
▪ Components
▪ Muscle spindle
1. Muscle length
2. Rate of change
▪ GTOs (NTOs)
1. Monitor tension
▪ Joint receptors
1. Mechanoreceptors
▪ Cutaneous receptors
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28. Role of visual
pathway:
28
The visual proprioceptive system,
has neurons
that are specialized in responding
to movement of the
retinal image across the retina.

29. Visual factors that maintain posture:
▪ Reports information
▪ – Self-to-(supporting)
surface
▪ – Head position
▪ » Keep visual gaze
parallel with horizon
▪ Subject to distortion
▪ Components
▪ – Eye and visual tracts
▪ – Thalamic nuclei
▪ – Visual cortex
▪ » Projections to parietal
and
▪ temporal lobes
29

30. Role of vestibular
apparatus:
30
▪ Vestibular apparatus is the part of
labyrinth or inner ear.
▪ It plays an important role in
maintaining posture and equilibrium
through statokinetic reflexes.

31. Labyrinth:
31
▪ Labyrinth (inner ear) consists of
two structures:
▪ 1. Bony labyrinth
▪ 2. Membranous labyrinth.

32. SEMICIRCULAR
CANALS:
32
▪ Semicircular canals are the tubular
structures placed at right angles to each
other.
▪ Because of this type of arrangement,
semicircular canals represent the
threeaxes of rotation, i.e. vertical,
anteroposterior and trans verse axes.
▪ Semicircular canals are :
▪ 1. Anterior or superior canal
▪ 2. Posterior canal
▪ 3. Lateral or horizontal or external canal.

33. Mechanism of semi-circular canals:
▪ Superior Semicircular Canal
▪ Superior semicircular canal gives response to rotation in
anteroposterior plane (transverse axis), i.e. front to back movements
like nodding the head while saying ‘yes – yes’.
▪ Horizontal Semicircular Canal
▪ Horizontal semicircular canal gives response to rotation in horizontal
plane (vertical axis), i.e. side to side movements (left to right or right to
left) like shaking the head while saying ‘no – no’.
▪ Posterior Semicircular Canal
▪ Posterior semicircular canal gives response to rotation in the vertical
plane (anteroposterior axis) by which head is rotated from shoulder to
shoulder. 33

34. Transmission of impulses:
Receptor organ in
the otolith
membrane called
macula
Axons of the first
order neurons
(bipolar cells) form
vestibular
division of
vestibulocochlear
nerve.
These fibers reach
the medulla
oblongata and
terminate in
vestibular nuclei.
Second order
neurons of this
pathway are
located in the four
vestibular nuclei.
Secondary
vestibular fibers
form four tracts:
Vestibulo-ocular tract
• Vestibulospinal tract
• Vestibuloreticular tract
• Vestibulocerebellar tract.
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35. Vestibular factors that maintain posture:
▪ Not under conscious
control
▪ Assesses movements of
head and body relative to
gravity and the horizon
▪ (with visual system)
▪ Resolves inter-sensory
system conflicts
▪ Gaze stabilization
▪ Components
▪ – Cerebellum
▪ – Projections to:
▪ » Brain stem
▪ » Ear
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36. 36

37. Posture
How the body maintains its posture?
37

38. “ ▪ Posture is maintained by
two main factors:
▪ Muscle tone
▪ Postural reflexes
38

39. Muscle tone:
▪ Muscle tone is defined as the state of continuous and passive partial
contraction of muscle with certain vigor and tension.
▪ It is also called tonus.
▪ It is also defined as resistance offered by the muscle to stretch.
39

40. 40

41. Postural reflexes:
▪ The postural reflexes help to maintain the body in upright and
balanced position.
▪ REFLEX ARC of postural reflexes is as follows:
▪ Afferent pathways of reflex arc come from the eyes, the
vestibular apparatus and the proprioceptors.
▪ Integrating centers are formed by neuronal networks in brain
stem and spinal cord.
▪ Efferent pathways consist of alpha-motor neurons supplying the
various skeletal muscles which form the effector organs.
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42. TYPES OF POSTURAL REFLEXES:
▪ Broadly they are of two types:
▪ Static reflexes: These are elicited by gravitational pull and
involve sustained contraction of muscles.
▪ Statokinetic reflexes: These reflexes, also called phasic
reflexes, are elicited by acceleratory displacement of the body.
They maintain a stable postural background for voluntary
activity.
▪ Both these types of postural reflexes are integrated at various
levels in the CNS from the spinal cord to cerebral cortex and are
affected largely by pyramidal pathways.
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43. Maintenance of posture:
▪ Decision for a particular posture may occur in the cortex,
planning and programming occur in the basal ganglia and
cerebellum, and the information comes down through the
pyramidal tract to the motor neurons supplying muscles.
▪ In a standing posture, the centre of gravity is acting in such a
way that the body falls forwards. So the antigravity muscles like
extensors of neck, back,hip,legs etc., should be in a contracted
state.
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44. ▪ In the normal standing posture of humans, the upper limbs are
slightly flexed, and the flexor group of muscles are the
antigravity muscles in the upper limb. The vestibular receptors,
proprioreceptors, visual receptors etc., play important role in
maintaining posture.
▪ In the standing posture, impulse coming through vestibulospinal
tract and reticulospinal tract also play an important role. If there
is a change in the position of head, the receptors in the utricle
and saccule are stimulated and some group of muscles contract
and the head is held erect or in a particular posture.
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45. 45

46. 46

47. 47

48. 48

49. Research
Postural control deficits in people with Multiple Sclerosis: A systematic
review and meta-analysis
49
Laura Comber et al
Gait and posture, Elsevier 2018

50. Research:
▪ A systematic literature search identified case-control studies
investigating differences in postural control across a diversity of task
conditions, with the exception of gait, between people with MS and
healthy controls. Meta-analysis was conducted where a variable was
presented by four or more studies.
▪ Forty-three studies of people with a mean Expanded Disability Status
Scale (EDSS) of 1.0 to 6.0 were included. Seven conditions of
assessment and 105 individual measurement variables relating to
postural control were included. Quiet stance was the only condition
(11 studies) possessing sufficient data to contribute to meta-analysis
Results indicate that regardless of task complexity or sensory
condition, people with MS display considerable deficits in postural
control in comparison to healthy controls. 50

51. Thanks
!!
Any questions?
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