1. Cerebellum 1

2. Objectives Identify the major lobes and regions of cerebellum.
Summarize the structure of the cerebellar cortex
Identify the deep cerebellar nuclei and their connections.
List the afferent and efferent connections of the cerebellum and their arrangement in cerebellar peduncles.
Describe the major functions of the cerebellum and how each side of the cerebellum controls the ipsilateral side of the body.
Explain the effects of lesions of cerebellum and motor disorder associated with cerbellar lesions.

3. CEREBELLUM From the Hindbrain. Position :
ORIGIN :
From the Hindbrain.
Position :
Lies behind Pons & Medulla separated from them by Fourth ventricle.
Situated in the posterior cranial fossa

4. THE CEREBELLUM It is covered by tentorium cerebelli
CONNECED TO THE BRAIN STEM BY:
Inferior, Middle & Superior Cerebellar Peduncles.

5. EXTERNAL FEATURES
It consists of two Cerebellar Hemispheres joined in midline by the Vermis.
Its surface is highly convoluted forming the Folia, separated by Fissures.

7. EXTERNAL FEATURES Folia: Transversely oriented gyri
3 lobes in each hemisphere: Anterior, Posterior, Flocculonodular
Neural arrangement: Gray matter (Cortex), White matter (Internal),
Arbor vitae (tree of life): distinctive treelike pattern of the white matter
Folium

8. Cerebellum Anterior Lobe Posterior Lobe
Primary fissure
Anterior Lobe
Regulation of
muscle tone,
coordination of
skilled voluntary
movement
Posterior Lobe
Planning and
initiation of
voluntary activity
Flocculo-Nodular Lobe (FN lobe)
Maintenance of
balance, control
of eye movements
Vestibulocerebellum
Spinocerebellum
Cerebrocerebelum
Folia

9. ANATOMICAL SUBDIVISION
Superior Surface
Anterroinferior Surface
Anterior lobe: in front of primary fissure, on the superior surface.
Posterior (middle) lobe: behind primary fissure (Between Primary & Secondary fissures).
Flocculonodular lobe: in front of secondary (Posterolateral) fissure , on the inferior surface .

10. LOBES OF CEREBELLUM Divisions of lobes Anatomical Flocculonodular lobe
Inferior surface
Anterior lobe
Divisions of lobes
Anatomical
Flocculonodular lobe
Anterior lobe
Posterior lobe
Posterior lobe
Flocculonodular lobe
Superior surface
Anterior lobe
Posterior lobe

11. Arbor vitae Arbor vitae cerebelli
•In latin “ tree of life” it is the white matter of cerebellum.
It is so called because of the tree like
appearance.
It brings sensory and motor sensations to and from cerebellum.
Fourth ventricle

12. Structure of the cerebellum
Outer grey matter: cerebellar cortex.
Inner white matter: cerebellar medulla.
Deeply seated nuclei in white matter: from medial to lateral:
Fastigeal nucleus.
Globose nucleus.
Emboliform nucleus.
Dentate nucleus: largest one.

13. CEREBELLAR CORTEX Divided into 3 layers: Outer Molecular layer
Intermediate Purkinje cell layer
Inner granular layer

14. Cerebellar Medulla
Consists of three types of nerve fibres in the white matter
Axons of purkinje cells
The final output of the cerebellar cortex. The only axons to leave cerebellar cortex to end in deep cerebellar nuclei specially dendate nucleus.
Mossy fibres
Originate in all the cerebellar afferent tracts apart from inferior olive. They end in the granular layer.
Climbing fibres
Originate in the inferior olive of the medulla. They end in the molecular layer

15. CEREBELLAR MEDULLA AFFERENT FIBRES:
Climbing fibres: from inferior olivary nucleus, relay to purkinje cells
Mossy fibres: rest of fibres:
From vestibular nuclei
From spinal cord
From pons
They relay to granule cells which in turn relay to purkinje cells

16. CEREBELLAR MEDULLA
Axons of Purkinje Cells are the only axons to leave the cortex to medulla:
The great majority of axons do not leave cerebellum & end in deep cerebellar nuclei, specially Dentate nucleus.
Some of axons leave cerebellum as efferent fibres.

17. CEREBELLAR MEDULLA EFFERENT FIBRES:
Most of efferent fibres are axons of deep cerebellar nuclei.
Main Efferents go to:
Vestibular nuclei
Red nucleus
Ventral lateral nucleus of thalamus.

18. FUNCTIONAL SUBDIVISIONSOF
THE CEREBELLUM

19. Functional (Evolutionary) divisions
Paleocerebellum
Neocerebellum
Archicerebellum

20. ARCHICEREBELLUM Vestibular Part of cerebellum: Flocculonodular lobe.
Green = Archi-cerebellum, Blue= Paleo-cerebellum Pink= Neo-cerebellum.

21. ARCHICEREBELLUM Nuclei Related: Fastigeal Afferents: from :
1- Vestibular apparatus of internal ear via vestibulo-cerebellar tracts
2- Vestibular nuclei (Vestibulocerebellar fibres),(through ICP)
Efferents: to Vestibular nuclei (through ICP)
Function: controls Balance (via vestibulospinal & reticulospinal tracts).

22. PALEOCEREBELLUM Spinal Part of cerebellum: Vermis & Paravermis
Green = Archi-cerebellum, Blue= Paleo-cerebellum Pink= Neo-cerebellum.

23. PALEOCEREBELLUM Nuclei Related: globose & emboliform
Afferents: from spinal cord (dorsal & ventral spinocerebellar tracts through ICP & SCP, respectively)
(proprio-ceptive impulses from Ms.& tendons )
Efferents: to red nucleus (through SCP)
Function: influences posture & muscle tone (via Rubrospinal tract).

24. NEOCEREBELLUM
Cerebral Part of cerebellum: Rest of Cerebellum.

25. NEOCEREBELLUM Nuclei Related: Dentate
Afferents: It receives afferent impulses from the cerebral cortex+ pons Via cerebro-ponto- cerebellar pathway. (Pontocerebellar fibres) (through MCP)
Efferents: to Red nucleus but mostly to Ventral Lateral Nucleus of Thalamus (through SCP) then to motor cortex
Function: coordination of voluntary movements (via descending corticospinal & corticobulbar tracts).

26. Summary of classification
Classification by development
Archicerebellum
Paleocerebllum
Neocerebellum
Classification by Afferent Connection
Vestibulocerebellum
Spinocerebellum
Pontocerebellum
Classification by Efferent Connection
Vermis
Paravermal Region
Cerebellar Hemisphere
Archicerebellum
Nodulus
Archicerebellum
flocculus
Palaeocerebellum
Neocerebellum
Spinocerebellum
Pontocerebellum
Vestibulocerebellum

27. Functions of cerebellum
 Maintenance of Equilibrium
- balance, posture, eye movement
 Coordination of half-automatic movement of
walking and posture maintenace
- posture, gait
 Adjustment of Muscle Tone
 Motor Leaning – Motor Skills
 Cognitive Function

28. CEREBELLAR LESIONS MIDLINE LESION: Loss of postural control.
UNILATERAL LESION: IPSILATERAL “Cerebellar ataxia” .Causes :
Incoordination of arm: intention tremor (on performing voluntary movements)
Incoordination of leg: unsteady gait
Incoordination of eye movements: nystagmus: rapid jerky eye movements
Slowness of speech: dysarthria Staccato speech

29. Cerebellar Ataxia 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
Remember:
IPSILATERAL

30. 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 stood on the floor.

31. SUMMARY
Anatomically, the cerebellum is divided into: anterior, posterior & flocculonodular lobes.
Developmentally & functionally, it is divided into: archi- paleo- & neocerebellum.
Archicerebellum (flocculonodular lobe) is the oldest part of cerebellum, related to fastigeal nucleus, connected to vestibular nuclei & concerning for control of body balance.

32. SUMMARY
Paleocerebellum (vermis & paravermis) is related to globose & emboliform nuclei, connected to spinal cord & red nucleus & concerned with regulation of posture & muscle tone.
Neocerebellum (most of human cerebellum) is related to dentate nucleus, connected to pons, thalamus. Its final destination is to motor cortex. It is concerned with coordination of voluntary movements.
Cerebellar lesions lead to ipsilateral incoordination (ataxia).