Cerebellar Lecture Flashcards
Cerebellum is located: to teh 4th ventrilce
posterior
What 3 pairs of arteries supply the cerebellum:
SCA- Superior cerebellar artery (from basilar)
AICA- Anterior Inferior Cerebellar Artery from basilar
PICA from veretebral
name of the convolutions on the cerebellum
folia
Anterior lobe lies:
anterior to the primary fissure
Posterior lobe lies:
posterior to primary fissure
includes cerebellar tonsils (medial inferior part)
Cerebellar tonsils lie on:
posterior lobe
– tonsilar herniation is of clincal significance
Parts of floculonodular lobe:
1:
2:
1 nodule (partis) 2 flocculi
The nodule and flocculi are separated from posterior lobe by
posterolateral fissure
The flocculonodular lobe forms the:
vestibulocerebellum: control of equilibrium, balance, and eye movements
vermis along midline
and function
vermis: part of spinocerebellum
CONTROLs axial and proximal limb movements
Longitudinal subdivision:: Intemediate zone of cerebral hemi
-function
part of spinocerebellum
Controls distal limb movments
Lateral zone of cerebellar hemissphere:
part of cerebrocerebellum
PLanning and initiaition movments
Excitatory afferent from contralateral inferior olivary nuclues that synapse directy onto PKJ
Climbing fibers
Excitatory afferent from all other sources (besides olives) that synapse with granule cesll – which synapse with PKJ
Mossy fibers
Ihnibitory output neurons of the cerebellar cortex
PKJ
Granule cells are excitatory/inhibitory
excitatory
Baskey cells :
ihibitory interneurons
stelalate cells are:
inhibitory interneurons
What makes up the MOlecular layer of cerebellum
(5) parts
Dendrites of PKJ
Parallel fibres from axons of granule cells (excitatory)
Climbing fibers from contralateral infereior olivary nucleus (exicatory)
Stellate (inhibitory)
Basket (inhibitory)
each parallel fiber activates up to_____ PKJ
each climbing fibers innervates _______PKJ but each PKJ can only have 1 climbing giver
500
1-10
1
What goes on in the PKJ cell layer
-where does it send output to
PKJ cells are inhibitory (GABA) and output goes only to deep cerebellar nuclei
Components of granule cell layer: (3)
Granule cells~ excitatory
Golgi cells~ inhibitory
Mossy fibers (exicatory) and synpase with lots of granule cells
Where does the white matter lie?
beneath the granule cell layer
The major output neurons of the cerebellum as a whole
Deep cerebeller nuclei
DCN recive excitatory input from:
climbing and mossy fibers~ collaterals of afferents to cerebellar cortex
DCN receive inhibitory input from
PJK cells of cerebellar cotex
OUT put from DCN is :
Excitatory
Three sets of nuclei that make up DCN
Dentate: largest/lateral from lateral zone
Interposed nuclei: intermediate/from intermediate zone
Fastigial:medial/ from vermis
Circuit of Clmibing fibers
Excite PKJ–>which inihbit DNC–>which excite output to other regions
Circuit of Mossy fibers
Excite granues–>which form parallels–>excite PKJ–> inbit DCN–> excite output to other regions
Circuit of inhibitory interneurons:
baskets + stellate –> inihbit PKJ and
Golgi cells in granule layer –> inhibit the granules
Functions of Vestibulocerebellum: Floccunodular lobe and inferior vermis functions
balance and equilibruim while moving, controls eye mvmts, coordinates head/eye mvmnts
Afferent inputs to Flocculonodular lobe
Vestibular labytinth (isp semicircular canals) direcltly vestibular labrything-->Vestibular nuclei Visual centers (LGN, supeior colliculus and visual cortex)-->pontineds
Vestibular nuclei gives rise to:
Vestibulospinal tract (axial musculature) Medial longitudinal fasiculus: head/eye movments
Spinorcerebellum (vermis and intermediate zone) fnxs
Vermis controls axial/proximal msls
Intermediate zone: control of distal limb mscls
*both for ongoing execution of movements
Spinocerebellum afferent inputs:
Ispilateral sp cd and lower medulla project via:
Dosal spinocerebellar tract
Cuenocerebellar tract
Spinocerebellum afferent inputs:
Contralateral inferior olivary nucleus project via:
Olivocerebellar tract
Spinocerebellum afferent inputs:
All three tracts travel w/in the _______ to reach the spinocerebellm
Inferior Cerebellar peduncle
The ispilateral spinal cord crosses the midline to contralateral _______ upwards to the Superior Cerebelar peduncle then recrosses the midline to the _______
Ventral spinocerebellar tract (it’s contralatera)
(still contralateral in the Superior cereellar peduncle
recrosses to IPSILATERL SPINOCERebellar lob
Spinocerebellum Major Efferents:
Cerebellar cortex–> DCN– to the
SCP
How does vermis get to Axial and proximal muscles?
Sends efferents from vermis–>DCN–> brain stem–> medial descending system–> control over axial and proximal mslces
How does vermis get to motor and premotor cortex?
Sends efferents from vermis –> DCN–> Thalamus–> motor/premotor cortex for voluntary movements
How do afferents from Contralatearl cortex get to teh Lateral part of the cerebrocerebellum (part for planning and mental rehersal)
Contralateral cotex –> Corticopontine tract–> pontine nuclei –> through middle peduncle to the cerebellum
Cerebrocerebellum (lateral efferents) major efferents:
Starts lateral cerebrocerebellum–>
to DCN—> (contralateral)
Red nucleus midrain –>
Thalamux –> Motor and Premotor Cortex
What two paths do the lateral efferents from the cerebrocerebellum take once they reach motor cortex?
Motor cortex--> Corticospinal --> corsses isp --> to spinal cord OR Motor cortex --> corticopontine--> Pons (this path stays contralateral) and back up to CDN or lateral zone
Monoaminergic afferent to cerebellum: ______fibers from Raphe nuclei
Serotninergic
plays modulatory role
Monoaminergic afferents to cerebellum: _______ fibers from Locus cerueleus
Nonadrenergic
plays modulatory role
General fnx of cerebellum
- balance and eye movement
- regulates posture by indirecly modulating outpout of major descending systems
- compare intection and actual movement
The Cerebellum recives info about plans for movement and premotor cortex via:
corticocerebellar tract
The cerebellum monitors integration of descending and peripheral infor regarding movment in spinal cord via
ventral spinal cerebellar tract
Cerebellum recieves feedback from sensory via
dorsal spinocerebellar trat during movement
Cerebellum projects to motor centers that send fibers to the spinal cord __________tract to adjust output of motor system
dentororubothralmic tract
Lesion of cerebelllum will
disrupt coordinated limb and eye movements, impair balance, reduce tone
Cerebellar lesions usually cause _______motor signs
ipsilateral
Major signs of cerebellum dysfunction
ataxia, hypotonia, intentiaonal tremor, dysdiadochockinesa, dysmetria, nystagmus, titubation
Damage to cerebellum can result in:
impaired motor learning
