1. ASHIQ DEPARTMENT OF ANATOMY
Cerebellum
ASHIQ
DEPARTMENT OF ANATOMY

2. Learning outcomes parts of cerebellum
External & internal features of cerebellum.
Describe the connections and lesions of
cerebellum.
Cerebral peduncles

3. Little Brain The cerebellum was called the “silent” area of
the brain because electrical stimulation did not give rise to any :
• conscious sensation, or...
• any muscle action
The cerebellum is a SENSORY structure.
• The sensory signals that it receives are not
consciously perceived, they are used to modify muscle action.

4. Cerebellum Latin word – small brain Largest part of hind brain
Situated in the posterior cranial fossa, behind pons and medulla .covered by tentorium ceribelli
weight grams
Aproxi:100 millions of neuron
Shape : Ovoid but constricted in the median plane,
Flatened from above downwards,
Widest from side to side

5. Position
Lies above and behind the medulla oblongata and pons and occupies posterior cranial fossa.
Cerebellum

6. Parts & surfaces of cerebellum
2 cerebellar hemispheres.
Vermis is the cerebellar substance connecting two hemispheres.
Surfaces:
Has superior & inferior surfaces.
Presents anteriorly a notch to lodge pons & medulla.

7. External features
Consists of two cerebellar hemisphere united in the midline by the vermis [ worm].

8. External features- surfaces
Two surfaces
Superior surface –
is elevated in the midline
forms the superior vermis
and continuous with cerebellar hemispheres
Inferior surface -
It is grooved in the midline separating the hemispheres
Inferior vermis lies in the deep groove
and is limited on each side by vallecula

9. Fissures of cerebellum
Surfaces & vermis of cerebellum are traversed by fissures.
Prominent fissures:
Fissura prima.
Horizontal fissure.
Posterolataeral fissure.

10. Primary Fissure

11. External feature – fissures and sulci
There are numerous transverse fissures
They are called as folia
There are three important fissures
Horizontal fissure
It is the junction of superior and inferior surfaces (13)
Primary fissure (15)
It appears on the superior surface
It is ‘V’ shaped with apex directed dorsally
It is the junction of anterior two thirds with posterior one third
It separates anterior lobe from posterior lobe

12. Lobes Horizontal fissure Anterior lobe corpus of cerebellar
Primary fissure
Posterior lobe
Horizontal fissure
Flocculonodular lobe
Posterolateral [dorsolateral]
Fissure
Retrotonsilar fissure

13. Fissures & lobes Three deep fissures: Three lobes: Primary fissure
Horizontal fissure
Posterolateral fissure
Three lobes:
1.Flocculonodular lobe
flocculus and nodule
2.Anterior lobe
3.Posterior lobe

14. External feature – cerebellar notches
There are two notches
Anterior and posterrior
Anterior notch
it is ‘V’ shaped
It lodges pons and medulla
Posterior notch
It is narrow
It lodges falx cerebelli

15. Posterolateral fissure
It is first to appear
It appears on the inferior surface in the anterior aspect
It separates flocculonodular lobe from rest of cerebellum
Nodule is the portion of vermis
Flocculli are portions of cerebellar hemispheres

16. Cerebellum with various parts
1. Crus cerebri
2. Subsrtantia nigra
3. Red nucleus
4. Cerebral aqueduct
5. Tectum
6. Central lobule
7. Culmen
8. Declive
9. Wing of the central lobule
10. Quadrangular lobule
11. Simple lobule
12. Suprior semilunar lobule
13. Horizontal fissure
14. Superior posterior fissure
15. Primary fissure
16. Posterior cerebellar
incisure
17. Interpeduncular fossa

17. Internal structure Gray matter lies externally called cortex
White matter lies internally called medulla
There are central cerebellar nuclei embedded in the medulla

18. Arbor vitae The surface of cerebellum is laminated in appearance
Each is called folia
Deep inside folia there is white matter [like Branches of the
Tree]called arbor vitae
They are capped by gray matter called as cortex

19. Functional divisions
Three parts: • Vestibulocerebellum (archicerebellum), responsible for balance and eye movements. • spinocerebellum (paleocerebellum). • Cerebrocerebellum (neocerebellum).

20. Three functional divisions
Vestibulocerebellum
Archicerebellum
Flocculonodular lobe +Lingula
Spinocerebellum
Paleocerebellum
Vermis and intermediate zone
Cerebrocerebellum
Neocerebellum
Lateral zone
Vermis
Intermediate zone
Lateral zone
Flocculonodular lobe

21. Vestibulocerebellum-flocculonodular lobe
The flocculus and the nodulus (flocculonodular lobe) - vestibulocerebellum.
• Phylogenetically the oldest part.

22. Spinocerebellum

23. Cerebrocerebellum

24. Functional lobes of cerebellum
‘H’ is the anterior lobe – function muscle tone
‘I’ is the posterior lobe – function coordination
‘G’is the flocculonodular lobe – function equilibrium

25. Connections and function of cerebellum
Vestibulocerebellum-
Connections:
Afferents: receive input from vestibular nuclei and primary vestibular
Efferents: projects to the vestibular nucleus → vestibulospinal tract and medial longitudinal fasciculus → motor neurons of anterior horn
Function: involved in eye movements and maintain balance.

26. Connections and function of cerebellum
Spinocerebellum-
Connnection
Afferents: receive somatic sensory information via spinocerebellar tracts
- Efferents:
Vermis projects to the fastigial nucleus → vestibular nuclei and reticular formation → vestibulospinal tract and reticulospinal tract → motor neurons of anterior horn
Intermediate zone projects to the interposed nuclei
Contralateral red nucleus → rubrospinal tract →motor neurons of anterior horn
Contralateral VI →cerebral cortex→ coticospinal tract→motor neurons of anterior horn.
Function: control of muscle tone and coordination of muscle movement on the same side of the body.

27. Connections and function of cerebellum
Cerebrocerebellum-
Connection:
Afferents: receives input from the cerebral cortex via a relay in pontine nuclei.
Efferents: projects to dentate nucleus → primary motor cortex → corticospinal tract → motor neurons of anterior horn.
Function: participates in planning movements.

28. Cerebellar peduncles Three peduncles:
There are three peduncles
They contain fibers which connect cerebellum with brain stem
Inferior cerebellar peduncle connect with medulla and spinal cord, contain both afferent and efferent fibers.
Middle cerebellar peduncle connect with pons, contain afferent fibers.
Superior cerebellar peduncle connect with midbrain, contain mostly efferent fibers.

29. Inferior Cerebellar peduncle
Inferior cerebellar peduncle connects with – medulla oblongata
It consists of mainly afferent fibers
The afferent fibers :
Posterior spinocerebellar tract
Vestibulocerebellar tract
Olivocerebellar tract –arises from inferior olivary nucleus
Posterior external arcuate fibers
Anterior external arcuate fibers
Stria medularis
Reticulocerebellar
Efferemt fibers :
Cerebello-olivary
Cerebello-vestibular
Cerebello-reticular

30. Middle cerebellar peduncle
It connects cerebellum with pons
It consists of entirely afferent fibers
Afferent fibers arise in the nuclei pontis of the opposite side
They are crossed ponto- cerebellar
They are the second neurons of cortico-ponto-cerebellar pathway

31. Superior cerebellar peduncle
It connects cerebellum with midbrain
It consists of mainly efferent fibers
Afferent fibers
Anterior spinocerbellar tract
Rubrocerebellar
Efferent fibers
They form the major output
They arise in the dentate nucleus
They pass to midbrain
Decussate with the opposite side
Divide into ascending and descending
Ascending pass to red nucleus and thalamus
Descending end in the olivary nucleus and reticular formation

32. Deep nuclei of cerebellum nuclei
They are deeply placed in the white matter
Lateral to medial they are 4 in numbers
DEGF
D- Dentate
E- Emboliformis
G – Globosus
F- Fastigius

33. Cerebellar nuclei - fastigius
It lies close to the midline
The oldest nucleus
Associated with archicerebellum

34. Cerebellar nuclei – globosus and emboliformis
They are more recent and are associated with paleocerebellum

35. Dentate nucleus It is the largest and the chief nucleus
It is shaped like a crumpled bag
With hilus facing medially
Through it most of the supreior cerebellar peduncle emerges
It is the most recent nucleus and associated with neocerbellum

36. Dentate nucleus It receives afferents from the lateral hemispheres
And receives collaterals from the mossy and climbing fibers
Efferent's pass in the superior cerebellar peduncle
Terminate mostly in the red nucleus
Dentatorubrospinal patyhway
Thalamus
Dentatothalamocortical pathway

37. Deep nuclei of cerebellum
Cerebellar cortex
Fastigial nucleus
Globose nucleus
Dentate nucleus
Emboliform nucleus
White matter

38. Structure of cerebellum
Outer grey matter called the cortex & inner white matter.
Deep nuclei are grey matter embedded in the white matter.
The cortex (grey matter) is divided into :
Outer molecular layer
Middle Purkinje cell layer
Inner granular layer

39. Structure of the cerebellum

40. Histology Cortex is uniform in structure It consists of three layers
Molecular layer
Purkinje cell layer
Granular layer

42. Molecular layer Molecular layer consists of
Stellate and basket cells
Dendrites of purkinje and golgi cells
Axons of granule cells which are T shaped

43. Purkinje layer Purkinje cells are large flask shaped cells
At the junction of molecular and granule layers
They are the principal neurons of cerebellum
Dendrites arise from neck and pass into molecular layer
Axons arise from bottom and pass through granule layer and end in the cerebellar nuclei

44. Granular layer
Golgi cells lie at the junction of molecular and granular layer
Their dendrites pass into molecular layer and axons synapse with granule cells
Granular layer consists of numerous granule cells
Their axons pass into molecular layer and divide into in T shapes manner

45. Afferent and efferent fibers of cerebellar cortex
Afferent tracts that constitute climbing fibers are mainly olivocerebellar
They end in the purkinje cells
Most afferent tracts are mossy fibers
Mossy fibers end in the granule cells of cerebellum
Efferent fibers
Are axons of purkinje
Which end in the cerebellar nuclei
Both mossy and climbing fibers are excitatory
In summary of all the cells granule calls are excitatory

46. Blood supply of cerebellum
Arterial supply:
Superior surface:
Superior cerebellar artery- branch of basilar artery.
Inferior surface:
Anterior inferior cerebellar artery -branch of basilar artery
Posterior inferior cerebellar- branch of vertebral artery
Venous drainage:
Veins drain into neighbouring venous sinuses.

47. Cerebellum Function  Maintenance of Equilibrium
- balance, posture, eye movement
 Coordination of half-automatic movement of
walking and posture maintenace
- posture, gait
 Adjustment of Muscle Tone
 Motor Learning – Motor Skills

48. Balance

49. Motor Skill
Pablo Casals

50. Clinical Anatomy

51. Tonsils

52. Cerebellum Clinical Syndromes
Ataxia: incoordination of movement.
gait ataxia (unsteady gait).
Intention Tremor
Hypotonia, Nystagmus
Archicerebellar Lesion: medulloblastoma
Paleocerebellar Lesion: gait disturbance
Neocerebellar Lesion: hypotonia, ataxia, tremor

53. Posture
Gait – Ataxia
Tremor

54. Cerebellar Ataxia a b c d Ataxic gait and position:
Left cerebellar tumor
a. Sways to the right in
standing position
b. Steady on the
right leg
c. Unsteady on the
left leg
d. ataxic gait d

55. Cerebellar Medulloblastoma
Cerebellar tumors on vermis
- Truncal Ataxia
- Frequent Falling
The child in this picture:
- would not try to stand
unsupported
- would not let go of the bed rail
if she was stood on the floor.

56. Finally remember 3’s

57. Cerebellum 3 parts - 2 hemispheres and central vermis.
3 functional parts -archicerebellum, paleocerebellum and neocerebellum..
3 cerebellar peduncles -superior,middle & inferior.
3 layers – outer molecular,middle Purkinje and inner granular.
3 functions - coordination of fine voluntary movements, regulates muscle tone & maintains balance (equilibrium).
4 deep nuclei -dentate,globose,emboliformis & fastigius.

58. Applied anatomy
Loss of equilibrium results in -Staggering or unsteady gait called as cerebellar ataxia
Pendular knee jerk due to reflex abnormalities
Hypotonia – due to loss of muscle tone there is diminished resistance to passive movement
Dysmetria –– it is overshooting the objective -the patient finds difficult to touch his nose called past pointing test

59. Cerebellar Cognitive Affective Disorder
Lesions of the posterior cortex and vermis
Impairment of executive functions
Planning, verbal fluency, abstract reasoning
Difficulties with spatial cognition
Visuo-spatial organization, visual memory
Personality changes
Blunting of affect, inappropriate behaviors
Language disorders
Agrammatism

60. Conclusions Cerebellar lesions produce Motor learning
Incoordination & errors not weakness
Lose ability to anticipate errors
Lose ability to correct
Motor learning
Requires sensory awareness
Implemented via the descending cortical and brain stem pathways
Cognitive and emotional disturbances
Anatomical connections to prefrontal and cingulate cortex (via thalamus)
No single function
Clearly mostly motor; learning, optimizes
Functions may apply to cognitive and emotional behaviors

61. ANY Questions ?

62. Happy New Year
Thank you