UNIT 7 - CEREBELLUM

Question 1

What is the cerebellum?

Answer 1

“our little brain!

• Important part of the motor system (balance, posture, muscle tone (tension at rest), and coordination of movement
• 50 billion neurons vs 20 billion in the brain

Question 2

External Organisation: three cerebellar peduncles / Vermis

Answer 2

Penudles = Bundle of axon

• The superior peduncle (midbrain)
• Middle peduncle (pons)
• Inferior peduncles (medulla)

Vermis = midline in the hemisphere of cerebellum

Question 3

External Organisation / Folia - Fissure

Answer 3

Folia (like gyri and sulci): allow a large number of neurons to be packed into a relatively small space

Fissurie divide cerebellum into three:

• Anterior
• Posterior
• Floccolondular

Primary fissure: Separate small from large
Small are posterolateral fissure = Vermis + flocculus

Question 4

Internal Organisation - Cerebellar deep nuclei:

Answer 4

> Outerlayer of gray matter - Inner layer is with white matter <
Cerebellar deep nuclei: is in the inner part inside white matter

Question 5

Internal Organisation = Three layers

MPG

Answer 5

> Molecular (outer)
Purknije (middle)
Granular (Inner)

Question 6

Internal Organisation - GRANULAR (INNER) LAYER

Answer 6

It consists of the cell bodies of granule cells.

(sends info to external layer) - Granule cell axon that carries this information to the cerebellar cortex is known as Parallel fibers:
> they originate from granular cells and extend to a molecular (outer) layer of the cortex

(parallel to each other)

Question 7

Internal Organisation - MOLECULAR (outer layer)

Answer 7

Mostly consist of dendritic arborisations of Purkinje cell as well as granule parallel fibers, they both synapse

> only cell in the cerebellum: Purkinje > carry axon to deep cerebellar nuclei

Question 8

Internal Organisation - PURKINJE (MIDDLE)

Answer 8

Consist of single row of the cell consists of Purkinje neurons.
> Communication between cortex)

They have Dendritic arborisations

• Receive excitatory input
• Parallel

Question 9

Internal Organisation

- Deep Cerebellar Nuclei

Answer 9

Deep Cerebellar Nuclei: Internal part of white matter

• Primary source > Efferent
• Dentate, Emboliform, Globose and Fastigial Nuclei
• Receive inhibitory signal from Purkinje via neurotransmitter GABA
• But have afferent neurons as well called: MOSSY FIBRES (branch out) & CLIMBING FIBRES (synapse directly)
  > Enter fibers through cerebellar peduncles

Question 10

Functional Organisation: APN

Answer 10

ARCHICEREBELLUM

PALEOCEREBELLUM

NEOCERREBELLUM

Question 11

Archicerrebellum

Answer 11

• Has connection with the fastigial deep cerebellar nuclei (the oldest part of the cerebellum)
  > Vestibular and reticular nuclei (balance)

> Influence muscle tone, posture, and balance

Question 12

Paleocerebellum

Answer 12

> Decend rubrospinal tract

Influencing muscle tone and posture

Question 13

Noecerebellum

Answer 13

• Dentate deep cerebellar nuclei
  > Ventral lateral nucleus of the thalamus

Influencing: planning, and coordination of movement, trajectory, speed, and force of movement

Question 14

Damage in different parts of the cerebellum

Answer 14

Flocculondular: posture and balance
Vermis: Sit or stand

Damage to the cerebellum produces a deficit in the ipsilateral side of body.
> Timing of rapid movement

Neocerebellum: Uncoordinated movement
> If in both sides: slow speech (dysarthria) breaking words + Ataxia (staggering)