Cerrebelum Flashcards
Loss of cerebellum function
Disturbances of: Gait Balance Stability Accuracy in reaching Motor plasticity NOT paralysis
Cerebellum actions
Regulates posture
Coordinates motor acts
Involved in language and cognition
Circuits are IPSILATERAL
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
Dysdiadochokinesis Atakia Nystagmus Intention tremour Slurred speech Heel shin in ordination
