Cerebellum

The cerebellum is best known as a motor part of the brain, serving to maintain ___ and coordinate _____

equilibrium // muscle contractions

T/F: The cerebellum makes a special contribution to synergy of muscle action (i.e., to the synchronized contractions and relaxations of different muscles that make up a useful movement).

TRUE - ability to contract and relax at same time in synchronization

The _____ ensures that contraction of the proper muscles occurs at the appropriate time, each with the correct force

cerebellum

Classic Cerebellar Deficits

• Ataxic, wide-based, unsteady gait

• Dysdiadochokinesia

• Difficulty with accurate movement

  • Decomposition of movement

  • Dysmetria (past-pointing)

  • Intention tremor

what is ataxia

not moving as one smooth movement

the ability to do rapid alternating movement back and forth that people with cerebellar deficits have issues with

Dysdiadochokinesia

Classic with Cerebellar Deficits is to have difficulty with accurate movement, including...(3)

•Decomposition of movement

•Dysmetria (past-pointing)

•Intention tremor (gets worse as they start to move - finger to nose)

central bottom of cerebellum is called ____

inferior vermis

cerebellum contains ___ that have implications for timing and spatial awareness for limb movements; contain many nuclei

folia

does the cerebellum have a homonculus?

YES

The cerebellum consists of a _____, or surface layer, of gray matter contained in transverse folds called ____, plus a central body of ____ ____

cortex // folia // white matter

Don’t Eat Greasy Foods

dentate, emboliform, globuse, fastigial

(the 4 deep cerebellar nuclei, from lateral to medial)

___ pairs of central nuclei are embedded in the cerebellar white matter

FOUR (fastigial, globuse, dentate, emboliform)

4 deep cerebellar nuclei

-fastigial

-globose

-emboliform

-dentate

what two nuclei are interposed and tend to work together with axial/postural muscles?

globose and emboliform

where does most of the output from cerebellum come from?

deep nuclei

what ventricle lines up with cerebellum?

fourth

3 pairs of cerebellar peduncles, composed of myelinated axons, connect the _______ with the _______

cerebellum; brainstem

T/F: the cerebellar nuclei are always excited

true!

The 4 deep cerebellar nuclei receive ______ (glutamatergic) collateral input from all incoming sensory information before the signals are processed by the ______ cortex.

excitatory; cerebellar

the region in and near the midline of the cerebellum is known as the _______

vermis

the region in and near the midline of the cerebellum is the vermis, and the remainder is the _______

hemisphere

The ____ vermis blends into the hemispheres, but the ____ vermis lies in a deep depression and is well delineated.

superior; inferior

how many layers of cells does the cerebellum have? what are they?

3 - molecular layer, purkinje layer, granular layer

____ pairs of cerebellar peduncles, composed of myelinated axons, connect the cerebellum with the brainstem

3 - middle, inferior, superior

cerebellar peduncles connect the cerebellum with what?

brainstem

middle cerebellar peduncle contains ____ fibers

pontocerebellar (afferent, coming from pontine nuclei)

restiform body is part of which cerebellar peduncle?

inferior

every bit of sensory info coming into cerebellum, axons synapse and send collaterals to all 4 deep nuclei and excite them via what NT?

glutamate (excitatory!) - deep nuclei are excited ALL the time --- this means cerebellar cortex has to inhibit it via outflow

what cranial fossa is cerebellum in?

posterior cranial fossa

what separates cerebellum from occipital lobe?

tentorium cerebelli

The region in and near the midline of cerebellum is known as the ____, the remainder is known as the ___

vermis // hemisphere

The ____ vermis blends into the hemispheres, but the ____ vermis lies in a deep depression and is well delineated

superior // inferior

The main mass of the cerebellum (all but the focculonodular lobe) consists of ____ and ___ lobes

anterior & posterior

The anterior lobe is the part of the superior surface rostral to the ____.

(+ describe what rostral means in this context)

primary fissure.

(here rostral = anterior to/in front of)

anterior lobe is ___ to primary fissure

rostral (anterior/in front of)

this fissure separates the flocculonodular lobe

posterolateral fissure

The cerebellar surface is folded into many narrow folia, with ___% of the cortical surface concealed in the intervening sulci

85%

the cerebellar cortex is about ___ the size of the cerebral cortex

3/4

the cortical area of the cerebellum is about ___ the cortical area of the cerebrum

3/4

The ____ cell layer consists of a single row of bodies of ____ cells, the large principal cells of the cerebellar cortex

purkinje; purkinje

this is the most superficial layer which is a synaptic zone and contains dendrites of the purkinje cells which branch profusely in a plane perpendicular to the long axis of the folium (remember folium refers to the narrow folds of the cerebellar cortex)

molecular layer

this layer is deep to the purkinje cell layer and contains closely packed interneurons with axons that extend into the molecular layer

granule layer

types of cells in granule layer (2)

granule cell, golgi cell

purkinje cells have dendrites that go into ___ layer in a perpendicular direction (sagittal plane) and axons that go into the ___ layer

molecular // granule

purkinje cells have _______ that go into molecular layer in a perpendicular direction (sagittal plane) and ____ that go into the granule cell layer

dendrites; axons

output of cerebellar cortex travels via what?

axons of purkinje cells to deep cerebellar nuclei

what NT does purkinje cell use?

GABA (inhibitory)

what are the small inhibitory interneurons located in molecular layer? (2)

basket and stellate cells

cells found in molecular layer (be specific)

axons of granule cells, dendrites of purkinje cells, basket cells, stellate cells

what is the ONLY excitatory cell in the cortex?

GRANULE!!!

output of cortex via purkinje cell is ____

INHIBITORY

axons of granule cells travel up to ____ layer and become known as ____ fibers

molecular // parallel ("telephone wire")

T/F: Purkinje cells have their dendritic arbor in a plane perpendicular to the folium and therefore each parallel fiber (granule cell) is in a position to contact several Purkinje cells

TRUE

The ____ cell is the primary excitatory (glutamatergic) cell of the cortex

granule

___ cells have dendrites that branch in molecular layer & have an axon that is inhibitory (GABA) to granule cell

golgi cells

fibers containing input to the deep cerebellar nuclei of the cerebellum are known as ___ or ___ fibers

climbing or mossy

climbing fibers are neurons that originate in the ____ and send their axons to the cerebellum to synapse on ____ cell dendrites

inferior olivary nucleus (located in the medulla oblongata);

purkinje

___ cells are located in molecular layer; their axons form a "basket" around the Purkinje cell bodies; inhibitory (GABA).

basket

____ fibers originate in the inferior olivary nucleus and synapse with the proximal dendrites of Purkinje cells.

CLIMBING

climbing fibers (excite/inhibit) purkinje cells and nuclei

EXCITE

Cerebellar afferents from other sources end as ____ fibers, each synapsing with the neurons in the granular layer in a formation known as a glomerulus - excite Granule and Golgi cells.

MOSSY

mossy fibers synapse with the neurons in the ___ layer in a formation known as a ____

granule // glomerulus

____ fibers excite granule and golgi cells

mossy

mossy fibers excite ___ & __ cells // climbing fibers excite ___ cells

granule & golgi // purkinje

mossy fibers and climbing fibers each send collaterals to the ____ nuclei and are (excitatory/inhibitory)

central cerebellar nuclei // excitatory

Four pairs of nuclei are embedded deep in the cerebellar white matter; in a lateral to medial direction, they are:

Dentate

Emboliform

Globuse

Fastigial

(Don’t Eat Greasy Foods)

The input to the cerebellar nuclei is from: (2)

•Sources outside the cerebellum

•The Purkinje cells of the cortex

extrinsic input from outside the cerebellum to the cerebellar nuclei comes from what fibers? (3)

pontocerebellar, spinocerebellar, and olivocerebellar

BOLD AND IN COLOR:

Whereas the input to the central nuclei from outside the cerebellum is ____; the input from Purkinje cells, which use ____ as their transmitter, is ____

excitatory // GABA // inhibitory

Crudely processed information in the central nuclei is refined by the ____ signals received from the cortex

INHIBITORY

T/F: the combination of the two inputs (extrinsic and intrinsic) to the cerebellar nuclei maintains a tonic discharge from the central nuclei to the brainstem and thalamus

TRUE - combo of inhibitory and excitatory output

which circuits contain more synapses: inhibitory or excitatory?

INHIBITORY

____ circuits, which include more synapses than do the ____ relays, serve to limit the area of cortex excited and the degree of excitation resulting from a volley of impulses delivered by a ____ fiber

inhibitory // excitatory // mossy

Mossy and Climbing fibers first excite neurons in the where before continuing to the cortex?

deep nuclei

purkinje cells inhibited = ____ deep cerebellar nuclei

exciting

(bc you’re inhibiting the inhibition of purkinje cells)

inferior peduncle cerebellar afferents

•Olivocerebellar fibers (Climbing fibers)

•Dorsal Spinocerebellar tract (Mossy fibers)

•Cuneocerebellar tract (Mossy fibers)

•Vestibulocerebellar fibers (Mossy fibers)

•Trigeminal sensory nuclei (Mossy fibers)

inferior peduncle cerebellar efferents (outflow)

•Cerebellar corticovestibular fibers (vestibular nuclei)

•Cerebelloreticular fibers

most efferent fibers come from what cerebellar peduncles?

superior

middle peduncle cerebellar afferents

Pontocerebellar fibers (Mossy fibers)

is there anything coming OUT of the middle peduncle?

NO!

superior peduncle cerebellar afferents

•Anterior Spinocerebellar tract (Mossy fibers)

•Trigeminothalamic (mesencephalic) (Mossy)

•Rostral Spinocerebellar tract (Mossy fibers)

superior peduncle cerebellar efferents

•Cerebellothalamic fibers (from cerebellar nuclei to VL of contralateral thalamus)

•Cerebellorubral fibers to ipsilateral red nucleus

memory tricks—

superior peduncle afferents: ART

middle peduncle afferents: the middle is PC

inferior peduncle afferents: x5

superior peduncle efferents: red thalamus

middle peduncle efferents: none!

inferior peduncle efferents: correct

superior peduncle afferents: ART

• anterior spinocerebellar

• rostral spinocerebellar

• trigeminothalamic (mesencephalic)

middle peduncle afferents: the middle is PC

• pontocerebellar fibers

inferior peduncle afferents: x5

• olivocerebellar

• cuneocerebellar

• dorsal spinocerebellar

• trigeminal sensory nuclei

• vestibulocerebellar

superior peduncle efferents: red thalamus

• cerebellorubral fibers (to ipsi red nucleus)

• cerebellothalamic fibers

middle peduncle efferents: none!

• none!

inferior peduncle efferents: correct

• cerebellar CORticovestibular

• cerebelloRETicular

output from superior cerebellar peduncle goes to ___ in the thalamus and then to cerebral cortex

VL

what is the blood supply of deep nuclei?

superior cerebellar artery

functional cerebellar modules (3)

-Vestibulocerebellum

-Spinocerebellum

-Pontocerebellum

what lobe is the vestibulocerebellum in?

flocculondolar

vestibulocerebellum recieves input from the ___ nerve & nuclei

vestibular

some afferents as they enter the vestibulocerebellum they synapse on the ___ nucleus

fastigial

The Vestibulocerebellum influences motor neurons through (3)

•vestibulospinal tract

•medial longitudinal fasciculus

•reticulospinal fibers

vestibulocerebellum is concerned with the adjustment of ___ in response to ____

muscle tone // vestibular stimuli

this functional cerebellar module coordinates the actions of muscles that maintain equilibrium and participates in other motor responses, including those of the eyes

vestibulocerebellum

The Spinocerebellum consists of the ____ of the ____ lobe together with the adjacent medial or paravermal zones of the hemispheres

vermis // anterior lobe

what tracts that convey proprioceptive and other sensory information terminate on the spinocerebellum? (2)

Spinocerebellar and Cuneocerebellar

The Spinocerebellum gets input from these tracts (3)

•Ant & post spinocerebellar tracts

•Cuneocerebellar tract

•Olivocerebellar tract

tracts that give input to spinocerebellum synapse on what deep nuclei on their way to cerebral cortex? (3)

fastigial, globose, and emboliform

The output of the spinocerebellum is focused primarily on the control of ___ musculature through vermal cortex and ____ nucleus for postural corrections

axial // fastigial

The output of the spinocerebellum is focused primarily on the control of ___ musculature through efferents of ___ & ___ nuclei for locomotion

limb // globose & emboliform