Cerebellum DLA

Question 1

Describe cerebellar structure

Answer 1

• Cerebellar cortex (analogous to cerebral cortex) underlies meninges
• Beneath cerebellar cortex is subcortical white matter (analogous to cerebral white matter)
• Embedded within the subcortical white matter are clusters of cell bodies (deep cerebellar nuclei – analogous to cerebral basal ganglia)
• Near deep cerebellar nuclei is the fourth ventricle (analogous to the lateral cerebral ventricles)

Question 2

Describe embryology and general structure of the ccerebellum

Answer 2

• Embryology: Metencephalic protuberance

• General Structure
• Right and left hemispheres separated by midline vermis
• Three lobes separated by two fissures.

Question 3

Describe the lobar structure of cerebellum

Answer 3

Flocculonodular lobe: Mediolaterally oriented strip situated ventrally on the cerebellum (separated from the posterior lobe by the posterolateral fissure)

• Anterior lobe: Superior to primary fissure
• Posterior lobe: Inferior to the primary fissure

Question 4

Describe functional Cerebellar anatomy

Answer 4

• Cerebellar hemisphere indirectly regulates ipsilateral body

• Multiple motor homunculi present
  
  • More medial structures regulate trunk
  • More lateral structures regulate limbs

Question 5

What is the function of the spino-cerebellum?

Answer 5

Anterior. Lobe

Activity: Sensory feedback (trunk and limb movement)

Question 6

What is the cerebro-cerebellum zone?

Answer 6

Part of posterior lobe

Integrating motor and sensory feedback (precise movements
– location and timing)

Question 7

What is the vestibulo-cerebellum zone?

Answer 7

In the Flocculomotor lobe

Afferents from vestibular apparatus (balance, eye
movements)

Question 8

Describe the cellular and synaptic organization of the cerebellar cortex

Answer 8

Three cortical layers :
Molecular layer
Purkinje cell layer
Granular layer

Granule cells in the granular layer receive inputs from mossy fibers then ascend to molecular layer

Parallel fibers are axons of granule cells that have bifurcated in the molecular layer

Parallel fibers excite Purkinje cells and local inhibitory interneurons in the molecular layer

Climbing fibers ascend to synapse directly on the dendrites of Purkinje cells, spreading excitation

• Signals can only travel to from the cortex to the deep cerebellar nuclei via the Purkinje cells
• Output from the Purkinje cells are inhibitory (GABA) to the deep cerebellar nuclei
• Deep cerebellar nuclear efferent fibers mediate cerebellar output

Question 9

What is the cerebellar nuclei?

Answer 9

Vermis and Flocculonodular lobe communicate with fastigial nuclei

Paravermis communicates with
interposed nuclei

Lateral hemispheres communicate with dentate nuclei