Cerebellum Flashcards
Functions of the cerebellum
Adjust output of UMN pathways
1) coordinates Rate, range, and force of outgoing motor movements
2) maintenance of posture
3) Planning and timing of complex movements (Piano, baseball etc)
DOES NOT act in awareness of sensory stimuli
Inferior cerebellar peduncles
Cerebellar input (from ipsilateral cx) spinocerebellar tract, vestibular input and from olive, vestibular system
Middle cerebellar peduncles
pontocerebellar fibers
input from the contralateral motor cx
Superior cerebellar peduncles
cerebellar output
Layers of cerebellum
Outer `1) Molecular layer (cell processes) 2) Purkinje Cell layer (1 cell thick) 3) Granule cells (mostly granule cell bodies) 4) Arbor Vitae (axons in and out)
Mossy fibers
bring in the vast majority of afferents into the cerebellum
cell bodies in the spinal cord, (primary afferents in DRG) vestibular nuclei, pontine nuclei
Output of cerebellar cx
PURKINJE NEURONS
GABA onto deep cerebellar neurons in the arbor vitae
modulate rate and force of ongoing movements in order to smooth them out
Output of the cerebellum
Deep cerebellar nuclei
**have baseline activity that is decreased by Purkinje and increased by mossy fiber projections
Climbing fibers
most powerful excitatory input onto the cerebellum
release aspartate 1000000x on a single Purkinje neuron
come from olivary nuc.
important for motor learning
Flocculonodular lobe
vestibulocerebellum
input from vestibular apparatus
deep nuc= fastigial nuc
targets medial motor systems
functions in balance, posture, coordination of vestibular reflexes (VOR)
**mostly ipsilateral effects
Lateral hemispheres
contains the cerebrocerebellum
input= motor cx (BA 4,6)
deep nuc=dentate
targets= Red nucleus, motor cx (4+6)
involved with initiation, planning, timing of complex motor movements
corticopontine fibers
tracts carrying information from the primary motor cx to the pontine nucleus in the cerebrocerebllar pathway
run in anterior limb of internal capsule
cuneocerebellar tracts
tracts carrying fine touch, proprioception, and vibration from UL to the spinocerebellar tracts
unconscious proprioception
Posterior spinocerebellar
bring in fine touch/proprioception/ vibration from LL
unconscious proprioception
tracts of the spinocerebellar tracts
rostral spinocerebellar
cuneocerebellar tracts (UL)
ant and post spinocerebellar (LL)
trigeminocerebellar tract
Vermis
Spinocerebellar
peripheral input= spinocerebellar tracts (axial and proximal postural mm.)
nuc=fastigial
targets=medial motor systems
function= axial and prox motor control
adjusts ongoing movements
Paravermal regions
spinocerebellar tracts (distal limbs)
nuc= interposed nuc
target=lateral motor systems
distal motor control to adjust ongoing movements
cerebellar lesions
deficits in coordination are ipsi to lesion
motor ataxia dysrythmia dysmetria intention tremor dysdiadochokinesia
Midline lesions
unsteady gait (truncal sway)
wide based stance
uncoordianted eye movements
lateral lesions
ataxia of limbs (appendicular ataxia)
past pointing
dysdiadochokinesia
SCA lesion
would affect the vermis and lateral cerebellar hemispheres
AICA lesion
most of the anterior portion, cerebellar peduncles would be lost
PICA
nodulus would be lost
Decorticate posturing
Loss of LMNs or UMNs in the corticospinal tract but rubrospinal tract remains intact so the arms and forearms are held in flexion
or…no modulation of the brainstem UMNs by the corticospinal system
decertebrate posturing
if the rubrospinal tract and LMNs/UMNs of corticospinal tract are damaged
