Cerebellum and control of postures and movements

1. Cerebellum and Control of
postures and movement
S. Parasuraman, M.Pharm., Ph.D.,
Associate Professor,
Faculty of Pharmacy, AIMST University

2. Learning Outcomes
• At the end of this session, the student would be able to:
– Explain the anatomy and Functions of the Cerebellum
– Explain the Regulation of Posture and voluntary
movements
– Explain the role of the Cerebellum in Motor skills
learning
– Explain the abnormalities in motor function in a
patient with cerebellar disorder and provide the best
insight into the function of the organ.

3. Cerebellum
• The cerebellum is situated behind the pons and
immediately below the posterior portion of the
cerebrum occupying the posterior cranial fossa.
• It is ovoid in shape and has two hemispheres,
separated by a narrow median strip called the vermis.
• The vermis, which is a central constricted area,
connects the hemispheres.
• Grey matter forms the surface of the cerebellum, and
the white matter lies deeply.

4. Cerebellum
• The cerebellum is similar to the cerebrum in that each
has hemispheres that control the opposite side of the
body and are covered by gray matter and surface
folds.

5. Functions of cerebellum
• The cerebellum is concerned with the coordination of
voluntary muscular movement, posture and balance. It
coordinates activities associated with the maintenance of
the balance and equilibrium of the body.
• Damage to the cerebellum results in clumsy
uncoordinated muscular movement, staggering gait and
inability to carry out smooth, steady, precise movements.
• It is also involved in certain cognitive functions, such as
language.
• The cerebellum plays a major role in adapting and fine-
tuning motor programs to make accurate movements
through a trial-and-error process.

6. Functional Subdivisions of the Cerebellum
• Vestibulocerebellum: It is involved in vestibular
reflexes and in postural maintenance.
• Spinocerebellum: It is involved in the integration of
sensory input with motor commands to produce
adaptive motor coordination.
• Cerebrocerebellum: It is involved in the planning and
timing of movements. In addition, the
cerebrocerebellum is involved in the cognitive
functions of the cerebellum.
Ref: https://nba.uth.tmc.edu/neuroscience/m/s3/chapter05.html [Last assessed on 06/11/2018]

7. Functional Subdivisions of the Cerebellum
• Other functions:
– Influence on autonomic system (mediated through the
hypothalamus and reticular formation)
– Influence on conduction in ascending sensory pathway
(through the reticular formation and thalamus)
– Control of eyeball movements (through vestibular
nuclei)

8. Control of body posture
and movements
Postural control is defined as
achievement, maintenance
or regulation of balance
during any static posture or
dynamic activity for the
regulation of stability and
orientation.

9. Control of body posture and equilibrium
• Afferents to cerebellum:.
– Vestibulocerebellar tracts:
carry input from the
vestibular nuclei, which
convey afferents from the
macula of saccule and
utricle for static
equilibrium and from the
ampullary crests of
semicircular ducts for
kinetic equilibrium.

10. Control of body posture and equilibrium
• Afferents to cerebellum:.
– Spinocerebellar and cuneocerebellar tracts: carry feedback
about tone of muscles or position of the limbs in space.
– Reticulocerebellar tracts: bring feedback about activities of
extrapyramidal tracts.

11. Control of body posture and equilibrium
• Efferents to cerebellum:.
– The flocculonodular lobe and fastigial nuclei project output
fibres through inferior peduncle to vestibular and reticular
nuclei of brain stem.
– The vermal cerebellum sends back the information to spinal
cord indirectly through fastigial nuclei.
cerebellum does necessary corrections for
maintaining posture and equilibrium without
participation of conscious

12. Control of muscle tone and stretch reflexes
• Afferents to cerebellum:.
– Spinocerebellar, cuneocerebellar and olivocerebellar tracts
carry proprioceptive and tactile inputs from the limbs, trunk,
neck and other parts of the body.
– Spinocerebellum also receives auditory and visual impulses
through tectocerebellar tract.

13. Control of muscle tone and stretch reflexes
• Efferents to cerebellum:
– The spinocerebellum is projected into the cerebellar nuclei—
fastigii, emboliformis and globossus.
Spinocerebellum regulates the postural reflexes by
modifying muscle tone.

14. Control of voluntary movements
• Cerebellum is not able to initiate any motor activity,
but coordinates movements initiated by the motor
cortex.
• Control of movements by cerebellum includes
regulation of time, rate, range (extent), force and
direction of muscular activity.

15. Control of voluntary movements
• Pathway of control of voluntary movements:
– Open feedback loop: Also known as cerebro-
cerebellocerebral connection or afferent efferent
circuit consists of “Cerebro-ponto-cerebellar tract”
and “Dento-rubro-thalamic cortical tract”.
– Closed feedback loop: It is formed by the fibres
from the cerebral motor cortex to the paravermal
cerebellum to the cerebral motor cortex.

16. Thank you