Cerebellum Flashcards
where is cerebellum located
posterior cranial fossa, below tentorium cerebelli
functions of cerebellum
- regulate equilibrium
- control mm tone and posture
- motor coordination for voluntary movements
cerebellum primary function
motor adaptation (modification in response to environment)
structure of cerebellum
- folia = gyri, fissures = sulci
- nodulus of vermis (vestibulocerebellum) in center
- paravermal area on either side of vermis
primary fissure
separates ant and post lobes
where do ant and post lobes each receive input from
ant: from SC
post: from pons
posterolateral fissure
separates nodulus from rest of vermis
what are the 3 deep cerebellar nuclei, what do they do
- dentate nucleus
- interposed nucleus
- fastigal nucleus
*have axons that leave the cerebellum
dentate nucleus
contributes most fibers in SCP, lateral hemisphere projects here
interposed nuc
made of 1. emboliform and 2. globose nuc, medial hemisphere projects here
fastigal nucleus
vermis projects here
inf cerebellar peduncle
- restiform body: input from SC and BS, monitors mm and limb moves
- juxtarestiform body: connects vestibular nuc and cerebellum
middle cerebellar peduncle
(brachium pontis)
largest, lateral to pons, afferents from contralat basis pontis, relays motor signals from cerebral cortex
what are the two largest paths into the cerebellum?
inf and mid cerebellar peduncles
superior cerebellar peduncle
(brachium conjunctivum)
mostly efferent fibers to red nuc and thalamus
major cerebellar outflow path
climbing fibers
- originate in inferiior olivary nucleus in rostral medulla
- travel in inf cerebellar peduncle
mossy fibers
- provide info from SC and BS
- travel in inf and mid cerebellar peduncle, synapse in granular layer
path of climbing and mossy fibers
go to purkinje cell layer (piriform) and synapse in molecular layer, go to deep cerebellar nuclei, exit via sup OR inf cerebellar pedunces
sup: to red nuc and thalamus
inf: to vestibular nuclei
cerebellar afferents
- SCTs (ant-sup ped, pot- inf ped, cuneocerebellar- inf ped)
- trigeminal n (all 3 peduncles)
- tectocerebellar tract (ipsilat colliculi)
- vestibulocerebellar tract (ipsilat vestib nuc)
- pontocerebellar tract (mid ped)
- olivocerebellar tract (inf ped)
- reticulocerebellar (inf ped)
what facilitates transmissions in climbing and mossy fibers
serotonergic and noradrenergic synapses
origin, representation, input and crossing of ASCT
origin: spinal border cells (T12-L5)
rep: trunk/leg
input: mechanoreceptors and move related interneurons
cross: at midline, again in cerebellum
origin, representation, input and crossing of PSCT
origin: clarkes nuc (T1-L2/3
rep: trunk/leg
input: mechanoreceptors in mm, joints, and skin
crossing: NO
origin, representation, input and crossing of CCT
origin: lat cuneate nuc in medulla
rep: trunk/arm
input: mechanoreceptors in mm, joints, and skin
crossing: NO
what is inf olivary nuc involved with
motor learning and the acquisition of new motor skills
how/where does sensorimotor cortex in olivocerebellar tract project
where does it get info from
via corticospinal collaterals onto ipsilateral olive
info from SC, red nuc, and cerebral cortex
purkinje cells at rest and with training
at rest: groups of olivary neurons cause complex spikes
w/ training: simple spikes
red nucleus (afferent tract) in/outputs
in rostral midbrain
- inputs: collaterals from 1. cerebral cortex descending to olive 2. cerebellar output fibers ascending to thalamus
- outputs: inhibitory signal to ipsilateral olivary nucleus
layers of cerebellar cortex
- molecular layer (top):
- purkinje cell layer: only axons to leave cortex
- granular layer: densely cellular
cortical afferents vs efferents
afferents (excitatory): glutaminergic
efferents (inhibitory) GABAnergic
where do purkinje cell axons end?
in deep nucleus
neuronal populations of deep nucleus
- source of mossy fibers into cortex
2. projection neurons w/ axons leaving cerebellum
functional zones
fractionated somatotopy in ant and post lobes
*axial mm by midline, limbs lat
- vestibulocerebellum
- spinocerebellum
- pontocerebellum/neocerebellum
vestibulocerebellum (afferents)
- in flocculonodular lobe and part of vermis
- input: from vestibular labyrinth and nuc
- output: to fastigal nuc
- fnctn: control eye movements in response to head moves, balance
spinocerebellum (afferents)
- in paravermal area, part of vermis
- input: from spinocerebellar tracts, BS
- output: interposed nuc (red nuc)
- fnctn: posture and gait, coordination of trunk and limb moves
pontocerebellum/neocerebellum (afferents)
- in lat cerebellar hemi
- inputs: from motor cortex (basilar pons), MCP
- outputs: dentate nuc (red nuc, VA/VL of thalamus)
- fnctn: planning timing of movements (UL), coordination of speech
