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Flashcards in Cerrebelum Deck (13)

Cerebellum actions

Regulates posture
Coordinates motor acts
Involved in language and cognition
Circuits are IPSILATERAL


Loss of cerebellum function

Disturbances of:
Accuracy in reaching
Motor plasticity
NOT paralysis


Anatomical divisions

Floculonodular lobe-> archicerebellum
Anterior lobe-> paleocerebellum
Posterior lobe-> neocerrebellum


Functional divisions of the cerrebellum

Outside-> pontocerrebellum-> co ordination of fine movements, language?-> dentate nucleus-> VL thalamus
Spinocerebellum-> posture and gait, adaptive motor co ordination, muscle tone via gamma neurones -> globose embiliform, interposed nucleu-> nucleus rubber
Middle-> vestibulocerebellum-> balance, axial muscle control, co ordination of eye/head movements-> fastigial nucleus-> vestibular nuclei, pontine reticular formation


Cerebellum features

Horseshoe shaped with 4th ventricle in the middle
Very tightly folded layer of cortex
White matter in middle-> tree shaped -> contains deep nuclei
Connect to brain stem via cerebellar peduncles ->two from pons
Superior-> output
Middle-> input
10% of brain volume 50% of brains neurones
Shallow ridges-> folia
Deeper transverse fissures-> 10 lobules
Vermis-> output to brain stem-> ventromedial descending spinal pathways


Inhibitory cerebellar cells

Stellate-> synapse with higher purkinje dendrites
Basket-> synapse with lower purkinje dendrites
Purkinje-> large cells, also synapse with climbing and parallel fibres, send fibres to central nucleus-> collateral branches to Golgi cells
Golgi-> synapse with granular


Excitatory cerebellar cells

Granular-> synapse with purkinje and mossy fibres
Mossy fibres


Cerebellar inputs

Contralateral Inferior olivary nucleus-> climbing fibres-> synapse with thousands of dendrites on one purkinje cell -> one fibre is needed to stimulate an action potential
Vestibular nuclei, spinal cord, cerebral cortex-> mossy fibres-> thousands of granule cells-> parallel fibres divide to 400-> 400 purkinje cells
Glomerulus-> mossy fibre terminal+granule cell dendrite+ Golgi cell bouton
Both glutamate-> excited purkinje -> inhibits vestibular and cerrebelar GABA
Interneurones all GABA on purkinje-> disinhibition of vestibular and cerebellar nuclei


Cerebellar output

Purkinje cell->
Vestibular nuclei-> spinal cord
Deep cerebellar nuclei->
Fastigial-> brain stem
Dentate-> thalamus
Emboli form and globose-> red nucleus and thalamus


Afferent pathways, mossy fibres

Input from 3 sources
Special sense->
visual and auditory from ipsilateral colliculi-> tectocerrebellar tract via superior peduncle
balance from ipsilateral vestibular nucleus-> vestibulocerebellar tract
Spinal cord-> muscles, skin of trunk, limbs-> ipsilateral inferiors peduncle-> spinocerrebellar and cuneocerrebellar tracts
spinal reflex arc-> pons-> superiour peduncle-> anterior spinocerrebellar tract
Cerebral cortex-> contralateral brain stem-> middle peduncle-> cortiopontinecerrebellar tract


Cerebellar afferents, Climbing fibres

Contralateral inferior olivary nucleus
Via the olivocerebellar tract
In put from basal ganglia, reticular formation, motor and premotor cortex and spinal cord


Efferent cerebellar pathways

Purkinje cells-> lateral vestibular nuclei-> balance info-> vestibulospinal tract
Majority of fibres leave via deep cerebellar nuclei:
Fastigial-> medial longitudinal fasiculus-> medial and superior vestibular nuclei-> regulate eye movement
Globose and embiliform-> superior peduncle->
reticular formation-> reticulo spinal tract-> posture and locomotion
red nucleus -> rubrospinal tract-> motor learning
Dentate-> dentatorubrothalamic tract-> superior cerebral peduncle-> red nucleus, ventral lateral nucleus of thalamus -> motor cortex


Cerebellar dysfunction

Intention tremour
Slurred speech
Heel shin in ordination