The cerebellum is located in the posterior of the brain and coordinates movement. It receives sensory information and regulates motor movements to produce smooth, coordinated muscle activity during voluntary actions like posture, balance, and speech. The cerebellum is divided into lobes and hemispheres and connects to other parts of the brain through three pairs of peduncles. It integrates sensory information and provides feedback to correct errors in movement timing and execution to allow for coordinated voluntary motor control. Damage can cause disturbances in muscle tone, posture, equilibrium, and coordination of voluntary movements.

1. CEREBELLUM & ITS
FUNCTION

2. INTRODUCTION
• The term cerebellum literally means “little brain”.
• It is a relatively small portion of the brain — about ten percent of the total
weight, but it contains roughly half of the brain’s neurons, specialized cells
that transmit information via electrical signals.
• The cerebellum receives information from the sensory systems, the spinal
cord, and other parts of the brain and then regulates motor movements.
• The cerebellum coordinates voluntary movements such as posture, balance,
coordination, and speech, resulting in smooth and balanced muscular
activity.
• It is also important for learning motor behaviors.

3. • The cerebellum lies dorsal to the brain stem in the posterior (occipital)
fossa.
• It is the largest part of hind brain. It is situated behind medulla and pons.
On each side it is connected to the brain stem by 3 peduncles.
• 1. By inferior cerebellar peduncle or restiform body to medulla.
• 2. By middle cerebellar peduncle—brachium pontis to the pons.
• 3. By superior peduncle—brachium conjunctivum to the midbrain.
INTRODUCTION

4. • Anatomically : cerebellum consists of two cerebellar hemispheres which are
connected by a medial vermis. Each hemisphere is anatomically divided into
three lobes.
• 1. Anterior lobe
• 2. Posterior lobe or middle lobe
• 3. Flocculonodular lobe
• Physiologically : cerebellum is divided into two parts.
• (a) Corpus cerebellum: It has two lobes—anterior and posterior lobes
separated by fissura prima.
DIVISIONS OF CEREBELLUM

6. • (b) Flocculonodular lobe: It is divided into two parts:
• (i) Anterior lobe includes lingula, lobulus centralis, culmen.
• (ii) Posterior lobe includes lobulus simplex, declive, tuber, pyramid,
uvula and parafloccule.
• Phylogenetically:
• Paleo cerebellum—anterior lobe, lobulus simplex, pyramid, uvula,
parafloccule hemisphere.
• Archi cerebellum-flocculonodular lobe.
PARTS AND FUNCTIONAL DIVISIONS OF
CEREBELLUM

7. PARTS AND FUNCTIONAL DIVISIONS OF
CEREBELLUM

8. PARTS OF SUPERIOR AND INFERIOR VERMIS

9. COMPONENTS & CONNECTIONS OF FUNCTIONAL
DIVISIONS OF CEREBELLUM

10. PEDUNCLES OF CEREBELLUM
• Cerebellar peduncles connect the cerebellum to the brain stem.[1] There are six
cerebellar peduncles in total, three on each side:
• Superior cerebellar peduncle is a paired structure of white matter that connects the
cerebellum to the mid-brain.
• Middle cerebellar peduncles connect the cerebellum to the pons and are composed
entirely of centripetal fibers.
• Inferior cerebellar peduncle is a thick rope-like strand that occupies the upper part of the
posterior district of the medulla oblongata.
• The peduncles form the lateral border of the fourth ventricle, and form a distinctive
diamond – the middle peduncle forming the central corners of the diamond, while the
superior and inferior peduncles form the superior and inferior edges, respectively.

12. CEREBELLAR INPUT PATHWAYS

15. MECHANISM
• 1. The afferent pathways to the cerebellum transmit proprioceptive,
kinaesthetic and sensory informations from all over the body.
• 2. Collateral extrapyramidal impulses from motor cortex, basal ganglia
and reticular formation are transmitted to cerebellum.
• 3. The cerebellum integrates these impulses and provides feedback
impulses to the cerebral cortex, basal ganglia and reticular formation that
correct error in the involuntary movements.

16. FUNCTIONS
• Cerebellum is not able to initiate any motor activities but assist the motor
actions initiated by other parts of brain. But it plays an important role in
controlling and coordinating voluntary and involuntary movements.
• 1. Coordination of Movement-the cerebellum controls the timing and pattern
of muscle activation during movement.
• 2. Maintenance of Equilibrium (in conjunction with the vestibular system).
• 3. Regulation of Muscle Tone-modulates spinal cord and brain stem
mechanisms involved in postural control.

17. CONTROL OF INVOLUNTARY MOVEMENTS
• Cerebellum controls unconscious, automatic and reflex movements or
involuntary movements.
• It coordinates subconscious gross movements.

18. CONTROL OF VOLUNTARY MOVEMENTS
• The cerebellum guides and controls all the voluntary movements on
both execution of goal oriented voluntary movements.
• The movements are accurate in :
• Time.
• Rate.
• Range.
• force and
• direction.

19. • There is a triangular relationship between motor cerebral cortex, cerebellum and skeletal
muscles.
• Motor impulses are originated at motor cortex. From the motor cortex impulses are transmitted
to the skeletal muscles. This information is also sent to the cerebellum.
• From the skeletal muscles and joints sensory impulses are continuously transmitted to
cerebellum.
• Cerebellum in turn sends feedback impulses to the motor cortex. This modifies the further
impulses transmitted to the skeletal muscles.
• This acts as a error correcting mechanism. The cerebellum ensures that muscular action is well
co - ordinated, movements are smooth and precise as to force, rate and extent.
• Thereby cerebellum helps the cerebral cortex in timing and sequencing of next successive
movement. It also plays a role in predicting events like rates of progression of auditory and
visual actions.
CONTROL OF VOLUNTARY MOVEMENTS

20. APPLIED
• Causes of cerebellar disease or damage
• 1. Abscess
• 2. Hemorrhage
• 3. Trauma
• 4. Thrombosis of the artery supplying cerebellum
• 5. Degenerative changes in the cerebellar cortex. Signs of cerebellar
lesion.

21. DISTURBANCES IN TONE AND POSTURE:
• 1. Hypotonia or atonia cerebellar lesion produce atonia or hypotonia of
skeletal muscles. This will disturb the postural reflexes and balance.
• 2. Disturbances in the attitude:
• A marked change is observed in attitude in unilateral lesions of cerebellum.
• The major attitude changes are
• (a) Rotation of head towards unaffected side.
• (b) Lowering of shoulder to same side of lesion
• (c) Abduction of legs to opposite side.

22. DISTURBANCES IN TONE AND POSTURE
• 3. Deep reflexes while eliciting tendon jerks, some slow oscillatory to and
fro movements are produced instead of brisk movements. This is known as
pendular movement.
• 4. Disturbances in equilibrium: While standing the legs are kept spread
to a broad base, while moving staggering, drunken gait is observed.
• Vertigo: Vertigo is a symptom, rather than a condition itself. It's the
sensation that you, or the environment around you, is moving or spinning.

23. DISTURBANCE IN MOVEMENTS
• (a) Ataxia—in coordinated voluntary movements.
• (b) Asthenia: Easy fatigability and slowness of movements.
• (c) Dysmetria: Inability to adjust the strength and duration of a contraction
required to accomplish a given act, (e.g., when the subject is asked to touch a
point with his finger he overshoots the mark or fails to reach it).
• Involuntary tremors occur during voluntary movements overshooting is
called hypermetria and falling short to reach is called hypometria.

24. PATHOPHYSIOLOGY OF CEREBELLUM
• Rebound phenomenon: If the patient is asked to attempt a movement
against a resistance which is then suddenly removed, the limb moves
forcibly in the direction towards which the effort was made. This is due
to absence of the breaking action of antagonistic muscles.
• Dysdiadochokinesis: Inability to execute alternating movements rapidly,
e.g., Flexion and extension of the fingers.
• Asynergia: Lack of coordination between different groups of muscles
such as protagonists, antagonists and synergists.

25. PATHOPHYSIOLOGY OF CEREBELLUM
• (f) Cerebellar nystagmus: (deviation of the eyes) it occurs due to
damage to flocculonodular lobes. Tremor of eye balls occurs at rest.
(When neither person nor the visual scene is moving). This is due to
ataxia of ocular muscle.
• (g) Gait: It becomes awkwardly with the feet wide base, well apart,
drunken gait.
• 6. Speech: It is slow and lalling (baby like). This is known as dysarthria.