Cerebellum Flashcards
location of cerebellum
sits in the dorsal aspect of the brainstem and forms the roof of the fourth ventricle
rostral to caudal organization & functions of cerebellum
1) anterior lobe (motor coordination)
2) posterior lobe (motor coordination = medial; motor planning = lateral)
3) flocculonodular lobe (vestibular, balance, and eye movements)
medial to lateral organization and function of cerebellum
1) vermis (midline) - motor coordination (rostral) and limbic function (caudal)
2) paravermis - motor coordination
3) lateral hemispheres - motor planning
functional terms for cerebellar organization
1) vestibulocerebellum
2) spinocerebellum
3) neocerebellum
vestibulocerebellum
*flocculonodular lobe
*coordinates balance, posture, and eye movements
spinocerebellum
*anterior lobe, vermis, & paravermis
*responsible for muscular coordination
neocerebellum
*lateral hemispheres
*responsible for movement planning and cognitive functions
lateral hemispheres of cerebellum - function and motor pathway influenced
*functions: motor planning for extremities
*motor pathway influenced: lateral corticospinal tract
intermediate hemispheres - function and motor pathway influenced
*function: distal limb coordination
*motor pathway influenced: lateral corticospinal tract and rubrospinal tract
vermis - function and motor pathway influenced
*function: proximal limb and trunk coordination
*motor pathways influenced: anterior corticospinal tract, vestibulospinal tract, and tectospinal tract
flocculonodular lobe - function and motor pathway influenced
*function: balance and vestibulo-ocular reflexes
*motor pathways influenced: medial longitudinal fasciculus
the cerebellum coordinates movements of which side of the body
IPSILATERAL SIDE (cerebellum decussates to contralateral cortex, which then decussates again to the contralateral body, thus affecting ipsilateral body)
classic cerebellar symptoms
1) delay in the initiation of movement
2) ataxia (intention tremor, dysmetria, dysdiadochokinesia)
3) hypotonia
4) unsteady gait
classic sign of ANY cerebellar lesion
cerebellar ataxia (loss of balance & wide-based gait)
dysmetria
*classic sign of cerebellar disorder
*loss of coordinated movement (example: inability to perform finger-to-nose test)
intention tremor
*classic sign of cerebellar disorder
*can’t get hand to target/tremor starts as you approach the target
dysdiadochokinesia
*classic sign of cerebellar disorder
*can’t make movements exhibiting a rapid change of motion (example, flipping hand in palm)
*indicates an issue with the spinocerebellum (coordination of movements)
3 layers of cerebellar cortex
1) granule cell layer (innermost)
2) purkinje cell layer (middle)
3) molecular layer (outermost)
inputs to the cerebellum are derived from what types of fibers
1) mossy fibers
2) climbing fibers
climbing fibers
arise from contralateral inferior olivary nucleus, wrapping the purkinje cell body and proximal dendrite
mossy fibers
all cerebellar inputs (other than those from the inferior olive); synapse on granule cells
important cell types found within the cerebellum
1) purkinje fibers
2) deep nuclei
purkinje fibers
*cerebellar neurons that receive numerous inputs
*project to deep nuclei
*INHIBITORY: release GABA onto the deep nuclei
deep cerebellar nuclei
*cells that send projections OUT OF the cerebellum to thalamus, red nucleus, vestibular nuclei, etc
4 important spinal cord fiber tracts that relay info about the limbs to the cerebellum
- cuneocerebellar
- posterior (dorsal) spinocerebellar
- rostral spinocerebellar
- anterior (ventral) spinocerebellar
cuneocerebellar tract
relays real time information about UPPER LIMB movements
posterior (dorsal) spinocerebellar tract
relays real time information about LOWER LIMB movements
rostral spinocerebellar tract
reflects activity about spinal cord interneurons of UPPER limb
anterior (ventral) spinocerebellar tract
reflects activity about spinal cord interneurons of LOWER limb
4 deep cerebellar nuclei
1) dentate nucleus (lateral-most)
2/3) interposed nuclei: globus and emboliform
4) fastigial nucleus (medial)
inferior cerebellar peduncles
*input to cerebellum, from:
-spinal cord
-brainstem
-vestibular nuclei
-inferior olive
*carries ipsilateral spinal cord information about proprioception
middle cerebellar peduncle
*input to cerebellum from PONS
superior cerebellar peduncle
*output from cerebellum
*carries efferents to the brainstem and the ventrolateral thalamus (VL is the relay to primary motor cortex)
tremors
repetitive, oscillating movements
resting tremors - structural association?
basal nuclei dysfunction
intention tremors - structural association?
cerebellum dysfunction
essential tremor - structural association?
possibly inferior olive dysfunction
symptoms of upper motor neuron damage
-paralysis or paresis
-loss of fine movement
-evolves to spasticity
*increased muscle tone
*hyperreflexia
*babinski sign
symptoms of lower motor neuron damage
-paralysis or paresis
-hyporeflexia
-loss of muscle tone
-fasciculation and fibrillation
-muscle atrophy
symptoms of cerebellar damage
*ataxia
-hypotonia
-intention tremor
-balance and gait
-brainstem signs
-nystagmus
symptoms of basal nuclei damage
-dyskinesia
-rigidity
-resting tremor
-gait and dyskinesia
-no brainstem signs
-symptoms get worse
