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Neuroanatomy > 12. Cerebellum > Flashcards

12. Cerebellum Flashcards

1
Q

Functions of the cerebellum

A
  • MOVEMENT REGULATION (corrects disparities between intended and ongoing actions, smooths execution) - does NOT initiate movement
  • involved in all phases of GAIT
  • Equilibrium
  • Eye movements
  • Regulation of muscle tone and posture
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2
Q

Anatomy

Location of the cerebellum

A
  • Internal to occipital bone
  • Separated from cerebrum via tentorium cerebelli
  • Rostral to medulla oblongata
  • Dorsal to pons
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3
Q

Anatomy

  • Describe the gross topographical vs developmental divisions of the cerebellum
A
  • Vermis centrally
  • Hemispheres laterally
  • Large body dorsally
  • Small flocculonodular lobe ventrally
  • Body divided in rostral and dorsal lobe
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4
Q

Anatomy

  • The body is separated from flocculonodular lobe via the ____ fissure
  • The body is divided into a rostra and caudal lobe via the ____ fissure
A
  • B/F = uvulonodular fissure
  • R/C lobes = primary fissure
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5
Q

Anatomy

Anatomy of flocculonodular lobe

A
  • 1 NODULUS: on caudal vermis, centrally
  • 2 FLOCCULUS: on each hemisphere, laterally
  • Joined via flocculonodular peduncle
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6
Q

Anatomy

Vestibulocerebellum - Phylogenetic name, topographical components, afferents (general), role

Table slide 11

A
  • Archicerebellum
  • Flocculonodular lobe
  • A: vestibula system
  • Equilibrium + reflexive eye movements in response to head position
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7
Q

Spinocerebellum - Phylogenetic name, topographical components, afferents (general), role

A
  • Paleocerebellum
  • Rostral + caudal vermis (except nodulus) + paraflocculus
  • Spinal cord (spinocerebellar tracts)
  • Posture, locomotion, gaze
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8
Q

Anatomy

Pontocerebellum or cerebrocerebellum - Phylogenetic name, topographical components, afferents (general), role

A
  • Neocerebellum
  • Middle vermis + rest of hemispheres
  • Cerebrum (via pons/middle cp)
  • Skilled mvts of the limbs
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9
Q

Difference between folia and lobule

A
  • FOLIUM: ridge of cerebellar cortex extending from one hemisphere to the other across midline
  • LOBULE: group of folium (vermal + horizontal)
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10
Q

Name and location of cerebellar white matter

A
  • Cerebellar medulla
  • In the cerebellum core
  • Form arbor vitae = extensions overlying each folia
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11
Q

Anatomy

3 CEREBELLAR PEDUNCLES: name, locate, brainstem connection, afferents vs efferents

Slide 15

A

From medial to lateral:
* Rostral: midbrain, mainly efferents
* Caudal: medulla + SC, mainly afferents
* Medial: pons, only afferents (transverse fibers)

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12
Q

Anatomy

3 CEREBELLAR NUCLEI: name, locate

A

From medial to lateral:
* Fastigial
* Interposed
* Dentate (lateral)

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13
Q

Anatomy

Cerebellar nuclei sends inhibitory or excitatory outputs?

A

Excitatory

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14
Q

Anatomy

FASTIGIAL NUCLEUS: Afferents and efferents

A

Works with VERMIS + FLOCCULONODULAR lobe

Afferents:
* Vermis (spinocerebellar inputs from axial muscles)
* Flocculonodular lobe (vestibular inputs)

Efferents (via cpp):
* Vestibular nuclei
* Reticular formation

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15
Q

Anatomy

INTERPOSED NUCLEUS: Afferents and efferents

A

Afferents:
* Paraflocculus (spinocerebellar inputs from limbs)

Efferents (via rcp)
* Red & olivary nuclei (midbrain)
* Reticular formation

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16
Q

Anatomy

DENTATE (lateral) nucleus: Afferents and efferents

A

Works with the lateral zone
Afferents:
* Contralateral motor cortex, via pontocerebellar fibers (mcp)

Efferents (via rcp):
* VLN (thalamus) - back to motor cortex
* Red nucleus (midbrain)
* Olivary nucleus (medulla)
* Pontine nucleus (pons)
* Reticular formation
* Pallidum

De lahunta; VLN, red nucleus, reticular formation, pallidum

17
Q

Development

Describe briefly the steps of cerebellar development

Slide 21

A
  • Arises from growth of ALAR PLATE into a RHOMBIC LIP that contains GERMINAL CELLS
  • 1st group of germinal cells mature into PURKINJE cells, forming the purkinje layer (middle)
  • 2nd group continues to divide and form that EXTERNAL GERMINAL layer.
  • Inner cells migrate and form the GRANULAR layer;
  • Others form the STELLATE cells of the molecular layer (?) they are in the granular layer…
  • Remaining cells form EPENDYMAL cells lining 4th ventricle
18
Q

Development

External germinal layer remains visible when post-natally in dogs and cats?

A
  • 84 days in kittens
  • 75 days in puppies
19
Q

Histology

Name the 3 cerebellar cortical layers

A
  • MOLECULAR: axons and telodendria of granular cells + rare basket cells
  • PURKINJE: large, flask-shaped purkinje cells
  • GRANULAR: mass of granule cells + scattered golgi (stellate) cells
20
Q

Name 4 cerebellar neurons (have cell bodies in the cerebellum)

A
  • Basket cells
  • Purkinje cells
  • Granule cells
  • Golgi (stellate) cells
21
Q

PURKINJE neurons: cell body, dendrites, axons

A
  • Dendrite: molecular layer
  • Axons (-, GABA): cerebellar nuclei (most), vestibular nuclei (those from flocculonodular lobe)
22
Q

GRANULE cells: cell body, dendrites, axons

A
  • Granular layer
  • Dendrites: receive + inputs from Mossy fibers
  • Axons (+, glutamate): bifurcate as parallel fibers in the molecular layer, intersect with Purkinje dendrites (activate those in exact same plane)
23
Q

Golgi (Stellate) cells: cell body, dendrites, axons

A
  • Granular layer
  • Dendrites: + inputs from mossy and parallel fibers
  • Axons (-, GABA /glycine): synapse on granule cells (feedback inhibition)
24
Q

Basket cells: cell body, dendrites, axons

A
  • Molecular layer
  • Dendrites: + inputs from parallel fibers
  • Axons (-, GABA): inhibit purkinje cell bodies in immediately adjacent plane
25
Q

Name the two afferent fibers of the cerebellum

A

Mossy & climbing fibers

26
Q

Common features of mossy and climbing fibers

A
  • Both excitatory (mossy = ACh, Climbing = aspartate)
  • Become mossy and climbing fibers only once in the cerebellum
  • Send + collaterals on cerebellar nuclei as they ascend
27
Q

Mossy fibers: origin and influence on Purkinje neurons

A
  • Spinal cord + brainstem;
  • Synapse on golgi cells + granular cells
  • Influence Purkinje neurons indirectly (via granule cells, Golgi cells, basket cells)

Note: activation of GOLGI cells cause inhibition of granule cells = less activation of purkinje cells = disinhibition of cerebellar nuclei

Note: activation of GRANULE cells = more activity of purkinje cells = inhibition of cerebellar nuclei

28
Q

Climbing fibers: origin and influence on purkinje neurons

A
  • Olivary nucleus (integration from extrapyramidal system - red nucleus, reticular formation, spinal cord proprioception)
  • Entwine / activate purkinje neurons directly
29
Q

Name the afferent pathways

A
  • 4 spinocerebellar tracts (general proprioception)
  • Ipsilateral vestibulocerebellar tracts (special proprioception)
  • Tectocerebellar tracts (special somatic afferents; visual + auditory)
  • Pyramidal & extrapyramidal tracts (UMN)

Spinocerebellar: ipsilateral
Vestibulocerebellar: ipsilateral
Pyramidal: via controlateral pontine nuclei
Extrapyramidal: via controlateral olivary nucleus

Climing fibers: extrapyramidal tracts
Mossy fibers: all others

30
Q

What are the efferent cerebellar fibers?

A

Purkinje fibers (gaba) - most to cerebellar nuclei, some (flocculonodular) to VN

31
Q

Cerebellar nuclei are…
* Initially activated by ?
* Inhibited by ?
* Disinhibited by ?

A
  • Mossy and climing fibers
  • Purkinje fibers
  • Golgi (stellate) cells
32
Q

Cerebellar efferents - Neuron 1-3

A

Neuron 1: Purkinje neurons (cerebellar cortex)
Neuron 2: Cerebellar nuclei
Neuron 3: ipsi VN, contra thalamus, reticular formation, red nucleus, tectum..

33
Q

Decussations - all tracts decussate in and out of the cerebellum, EXCEPT

A

Vestibular feedback circuits

34
Q
A

Neuroanatomy (20 decks)

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