Cerebellum

1. Cerebellum
Dr. Sai Sailesh Kumar G
Associate Professor
Department of Physiology
R.D. Gardi Medical College, Ujjain, Madhya
Pradesh.
Email: dr.goothy@gmail.com

2. Functional
anatomy
The cerebellum also called the small brain
In Latin, it means little brain
It is attached to the brainstem by three pairs of peduncles
1. Superior peduncle - midbrain
2. Middle peduncle- pons
3. Inferior peduncle- medulla oblangata
Afferent and efferent fibers pass through these peduncles

3. Anatomical
divisions
The cerebellum consists of two large
bilateral hemispheres and a median
worm like vermis
Later fissure divides the cerebellum into
flocculonodular lobe and corpus
cerebelli
Corpus cerebelli further divided into
anterior and posterior lobes by primary
fissure

5. Flocculonodular
lobe
Consists of nodule of inferior
vermis
Pair of floccule connected to
the nodule

6. Anterior
lobe
Vermis of anterior lobe consists of
Lingula
Central lobe
Culmen

8. Posterior
lobe
Consists of
Declive, folium vermis
Tubervermis, pyramid
Uvla

10. Morphological
subdivisions
of cerebellum
On phylogenetical criteria, the cerebellar
morphology presents three sub divisions
1. Archicerebellum/ vestibulo cerebellum
2. Paleo cerebellum / spinal cerebellum
3. Neo cerebellum / Cerebro-pontine
cerebellum

11. Archicerebellum
Consists of flocculonodular lobe
and lingula
Receives input from vestibular
nerve and medical and inferior
vestibular nuclei
Concerned with maintenance of
equilibrium, tone and posture of
trunk muscles

12. Paleocerebellum
Consists of anterior lobe except lingula,
pyramid and Uvula
Receives proprioceptive and
extraproprioceptive inputs from spino-
cerebellar, cuneo-cerebellar and rostral
spinocerebellar tracts
Concerned with the maintenance of tone
and posture of limbs

13. Neocerebellum
Consists of rest of the cerebellum
Receives input from pontine nuclei,
inferior olivary nucleus, from visual
and auditory senses
Concerned with smooth performance
of skilled acts by coordination of
movements and cognition

14. Functional
divisions
Three zones
Vermal or median – concerned with
movements of trunk and extensor muscle
tone
Intermediate zone- modify ipsilateral
movements and flexor muscle tone
Lateral zone – coordination of distal limb
muscles for skillful acts

16. Cerebellar
cortex
Three layers
Outer molecular layer
Middle purkinje layer
Inner granular layer

17. Cerebellar
cortex
Outer molecular layer
Consists of dendrites of
purkinje cells and golgi cells
Parllel fibers of granule cells
Stellate and basket cells

18. Cerebellar
cortex
Middle Purkinje layer
Consists of cell body of purkinje cells
The axons of purkinje cells descend into
white matter and terminate on cerebellar
deep nuclei and vestibular nuclei
Purkinje cells are stimulated by climbing
fibers and mossy fibers and inhibited by
the stellate and basket cells

19. Cerebellar
cortex
Inner granular layer
Consists of two types of cells
Golgi cells
Granular cells

20. Afferent
input to
cerebellar
cortex
The cerebellar cortex receives afferent input
from other parts of brain and spinal cord
through two types of nerve fibers.
Climbing fibers
Mossy fibers
Both these fibers are excitatory

21. Climbing fibers

22. Mossy fibers

23. Cerebellar circuit
 All output from the cerebellum is from the deep cerebellar nucleus
Climbing fibers from ION stimulates the deep cerebellar nucleus
Climbing fibers from ION stimulates Purkinje fibers
Mossy fibers stimulate deep cerebellar nucleus
Mossy fibers stimulate Purkinje fibers through granular cells
Granular cells give parallel fibers and these fibers stimulate Purkinje cells
Granular cells stimulates Golgi cells and these cells inhibits presynaptically the granular
cells
Granular cells stimulates stellate and basket cells and these cells inhibits deep nuclei

24. Cerebellar circuit
 All output from the cerebellum is from the deep cerebellar nucleus
Climbing fibers from ION stimulates the deep cerebellar nucleus
Climbing fibers from ION stimulates Purkinje fibers
Mossy fibers stimulate deep cerebellar nucleus
Mossy fibers stimulate Purkinje fibers through granular cells
Granular cells give parallel fibers and these fibers stimulate Purkinje cells
Granular cells stimulates Golgi cells and these cells inhibits presynaptically the granular
cells
Granular cells stimulates stellate and basket cells and these cells inhibits deep nuclei

26. Output from
cerebellum

27. Deep
cerebellar
nuclei
In the white matter of cerebellum, there are
four grey masses called deep cerebellar nuclei
Dentate nucleus
Nucleus globosus & Nucleus emboliformis –
collectively called as nucleus interpositus
Nucleus fastigii

30. Afferents
to
cerebellum
Cortico-ponto- cerebellar fibers –
conveys control from the cortex
Olivo-cerebellar tract- carries
proprioceptive inputs from whole
body
Rubro-cerebellar tract- carries
impulses from motor cortex and
distribute to dentate nucleus

31. Afferents
to
cerebellum
Ventral spino-cerebellar tract – conveys
information from muscles, joints of the lower
half of the body
Cuneo-cerebellar tract- Conveys information
from muscles, joints of upper half of the body
Vestibulo-cerebellar tract- Conveys
information from vestibular apparatus about
head and eye position and their movement

32. Afferents
to
cerebellum
Reticulo-cerebellar tract – Conveys
motor and sensory information
from different reticular nuclei
Tecto-cerebellar fibers –convey
visual and auditory information
from superior and inferior colliculi
Trigemino-cerebellar tract- carries
proprioceptive impulses from face
and head

33. Key points
Cerebellum receives
entire inputs via climbing
and mossy fibers
Uniform microstructure
in all the regions of
cortex
Lesion of one side
cerebellum causes signs
and symptoms on same
side of body
Cerebellum has direct
influence on extra-
pyramidal pathways

34. Efferents of
cerebellum
Cerebello vestibular tract
Arises from spino and vestibulo
cerebellum
Carries motor impulses to vestibular
nucleus and from there to spinal cord
and cranial nuclei III,IV,VI.

35. Efferents of
cerebellum
Cerebello-rubro-thalamo-cortical
tract
Arises from dentate nucleus
Carries motor impulses to red
nucleus, from there to thalamus
and cerebral cortex of opposite side

36. Efferents of
cerebellum
Cerebello-rubro-olivary tract
Arises from Ponto cerebellum
Carries motor program to red nucleus
and then to inferior olivary nucleus
Participates in mental rehearsal of
movement and motor learning

37. Efferents of
cerebellum
Cerebello-reticular fibers
Arises from spino cerebellum
Carries motor impulses to
reticular formation and from
there to spinal cord

38. Efferents of
cerebellem
Cerebello-thalamocortical
tract
Arises from the spino and
ponto cerebellum
Carries motor program to the
contralateral motor and
premotor cortex

39. Efferents of
cerebellum
Cerebello-olivary tract
Arises from spinocerebellum
Reaches inferior olivary nucleus of
same side
From olivary nucleus, olivo-spinal tract
arises and influences motor activity