1. Cerebellum
Kiranmayi S.

3. 50% of brain’s neurons, 10% of volume
Cerebellum
50% of brain’s neurons, 10% of volume
Can change movements as necessary
E.G. Walking or talking
Does not reach conscious awareness
Muscle synergy or coordination monitored
Important in running, speaking - all fluid movements

4. THE CEREBELLUM AND BASAL GANGLIA COORDINATE MOVEMENTS
THE CEREBELLUM IS INVOLVED IN PLANNING, COORDINATION, AND POSTURE
ANTERIOR AND POSTERIOR LOBES INVOLVED IN LIMB MOVEMENT
FLOCCULONODULAR LOBE IS INVOLVED IN EQUILIBRIUM AND POSTURE

5. Function of Cerebellum
Error Control Device - Monitor, Quality Control
Monitors outputs to muscles from motor cortex and sensory signals from receptors
Compares the efferent project plan with execution at motor action site
Considers related factors and makes adjustments

6. Evolution
3 main stages based on the complexity of movement
Archecerebellum – balance
Paleocerebellum – posture, locomotion
Neocerebellum – programming skilled and learned movement

7. tentorium cerebelli
"tent of the cerebellum"
dura mater that separates the cerebellum from the inferior portion of the occipital lobes.

8. Posterior Cranial Fossa
Fossa is a depression or cavity in the bone
Cerebellum, pons, and medulla oblongata sit in the Posterior cranial fossa

9. Located dorsal to pons and medulla
Cerebellar Anatomy
Seen from feet
Located dorsal to pons and medulla
In posterior fossa under tentorium cerebelli
Lobes
Floccular Nodular(small fluffy mass)
Anterior
Posterior
Anterior lobe (H)
Posterior lobe (I)

11. Longitudinally separated into hemispheres and cortices
Flattened Cerebellum
Longitudinally separated into hemispheres and cortices
Median (Vermal)
Vermis=worm
Paramedian (Paravermal
Lateral

12. Cerebellum Paramedian Primary Median Fissure Posterior Superior
Horizontal
Fissure
Prepyramidal Fissure
Posterolateral Fissure

13. Transverse Cerebellar Regions
Floccular nodular lobe (Archicerebellum )
Oldest, related to vestibular part of VIII
Regulates equilibrium through vestibulospinal tract
Anterior lobe (Paleocerebellum)
Rostral to Primary Fissure
General Sensory Receptors
Concerned with muscle tone and walking
Posterior lobe (Neocerebellum)
Newest and Largest, Receives afferent projections from contralateral sensorimotor cortex
Projects to contralateral motor cortex
Functions in coordination of fine and skilled movements

14. Longitudinal Cerebellar Regions
Vermis
Contributes to body posture
Paravermal region
Regulates movements of ipsilateral extremities (e.g. walking)
Lateral Zone
Regulates skilled movements of ipsilateral extremity (e.g. tying your shoe)

15. Cerebellar Connection
Three Peduncles
Inferior – afferent: mediate sensorimotor input to the cerebellum
Middle – afferent: same as above
Superior – efferent: transmit output from the cerebellum to the brainstem and on to the thalamus, motor cortex, and spinal cord
Varied afferents to Cerebellum :
spinal cord
brainstem
motor cortex
Afferenet:Efferent Ratio = 40:1
For each going from cerebellum to body, 40 coming in

16. Globose & emboliform nuclei
Cerebellar Nuclei
Neocerebellum
Dentate Nucleus
Globose & emboliform nuclei
Paleocerebellum
Fastigeal Nucleus
Vestibular Nucleus
Archecerebellum

17. Cerebellar Nuclei (Nuclei = deep cluster of neurons)
Dentate nucleus
Largest, communicates through cerebellar peduncle
Carries information important for coordination of limb movements (along with the motor cortex and basal ganglia)
Emboliform nucleus (medial side of the nucleus dentatus)
Regulates movements of ipsilateral extremity
Globose nucleus
Fastigial nucleus
Regulates body posture
Is related to the flocculo nodular lobe

18. Dentate Nucleus
Dentate
Nucleus
Pontine
Projections
Superior
Cerebellar
Peduncle
Pons

19. Somatotopic Organization
Tactile information
Ipsilateral anterior lobule
Bilateral paramedian lobules
Cerebral Cortex and Cerebellum have similar representations
Motor representation
Same area as sensory mapping
May have auditory and visual processing

20. Afferent Pathways (Inferior)
Vestibulocerebellar Tract
Info From Semicircular Canals Through Inferior Peduncle
Maintains Upright Posture
Dorsal Spinocerebellar Tract
Info From Reticular Nuclei (involved in regulation of sleep, respiration, heartbeat, etc.)
Unconscious Proprioception From Muscle Spindles, Golgi Tendons and Tactile Receptors

21. Afferent and Efferent Projections
Thalamus
Red nucleus
Superior Cerebellar
Peduncle
Middle Cerebellar
Peduncle (pontocerebellar
fibers)
Inferior Cerebellar Nucleus
(olivocerebellar fibers)

22. Afferent Pathways (Middle)
Info From Pontine Nuclei From Opposite Cerebral Cortex, Visual and Auditory Inputs
To Opposite Cerebellar Hemisphere

23. Afferent Connections & Functions
Equilibration – vestibular nuclei to archecerebellum through VIII nerve
Subconscious Proprioception – anterior lobe is ipsilateral
Feet – anterior, upper limbs posterior, head in located posteriorly in the superior vermis
Motor Control Circuits – coordinates muscle groups, smoothes muscle action, adjusts muscle tone so that force and its direction and extent are appropriate and accurate

24. Efferent Pathways
Cerebral cortex – dentato-rubro-thalamic route to the motor cortex
Red nucleus – limb movements
Reticular formation – muscle tone
Vestibular nuclei – equilibrium

25. Structured in Three Parallel Layers
Cerebellar Cortex
Structured in Three Parallel Layers
Molecular
Purkinje
Connecting Surface and Deep Cerebellar Nuclei
Source of All Efferent Fibers
Cerebellar Cortex
Granular
Have Mossy Fiber Axons to Purkinje Axons

26. CELL TYPES AND CIRCUITS IN THE CEREBELLUM

27. Purkinje cells – very large Golgi type I neurons.
Cerebellar Cortex
Molecular layer – superficial, has few cells and many fibers run parallel to the folia and form granular cells of the deep layer.
Satellite cells and Basket cell
Purkinje cells – very large Golgi type I neurons.
Large flask shaped cell bodies with profusely branched dendrites ( synapses)
Granular cells- vast numbers of small neurons with axons ascending into the molecular layer

28. PURKINJE CELLS ARE THE MOST PROMINENT OF ALL THE CEREBELLAR CELL TYPES
TWO INPUTS: CLIMBING FIBERS (FROM OLIVARY NUCLEUS) AND PARALLEL FIBERS FROM GRANULE CELLS
OUTPUT VARIES ACORDING TO INPUT: CLIMING FIBERS LEAD TO COMPLEX PATTERNS WHILE PARALLEL FIBERS GENERATE SIMPLE PATTERNS

29. CEREBELLAR LESIONS
IPSILATERAL DISTURBANCES
LATERAL LESIONS RESULT IN COORDINATION LOSS
LESIONS IN THE VERMIS PRODUCE ATAXIA (LOSS OF COORDINATION)
FLOCCULONODULAR LOBE LESIONS PRODUCE EQUILIBRIUM DISTURBANCE AND ATAXIA

30. Clinical Considerations
Signs of Dysfunction
Impaired Muscle Synergy
Reduced Muscle Tone
Evident in Skilled Tasks
Ataxia
Lack of Order and Coordination in Activities
Slow Movement (Bradykinesia)
Mild Muscular Weakness (Asthenia)
Asynergia
Speech difficulties (Ataxic Dysarthria)
affects respiration, phonation, resonance and articulation, but most pronounced in articulation and prosody.

31. Overview of Hypothalamus
Is very small
Weighs only about 4 grams
Brain=1400 grams
Contains a variety of specialized structures.

32. Functions of Hypothalamus
Autonomic nervous system regulation
Hormone production
Endocrine regulation
Circadian rhythm regulation
Limbic system interaction
Various
Temperature regulation
Feeding

34. Regulates Mechanism by
Receiving sensory information from all areas of the body.
Comparing sensory information with biological set points.
Adjusting the system to restore the body balance when deviations from biological set points occur.
Example Set points
Blood sugar, Hormone levels, Temperature, Sodium

35. Autonomic nervous system regulation
Influences PSNS through projections to brainstem PSNS nuclei
Posterior area influences SNS through projections to the lateral gray horn

36. Hormone Production
Magnocellular regions of the supraoptic and paraventricular nuclei produce oxytocin and vassopressin (ADH)
Transported via axonal transport systems (hypothalamohypophysial tract) to neurohypophysis􀁼
Released in circulation
Damage to supraoptic n. ⇒ diabetes insipidus

37. Hormone Production
Stimulating or inhibiting hormones are transported via the tuberoinfundibular tract and released in to the pituitary portal system and ultimately to the adenohypophysis

38. Cercadian rhythm regulation
Input from retina to suprachiasmatic nucleus is then sent through poorly defined projections to the pineal gland

39. Temperature Feeding Posterior n. conserves heat
Anterior n. dissipates heat
Fever starts – sweating
Fever ends – chills
Feeding
Lateral n. induces eating
Ventromedial n. inhibits eating