Cerebellum & Movement Flashcards
What are the functions of the cerebellum?
Voluntary movement coordination, error detection, balance, muscle tone, maybe cognition
What are the functions of the spino, ponto, and vestibulocerebellum?
S: unconscious proprioception, error detection
P: coordination of intended movements
V: balance, eye movements, posture
What parts of the cerebellum are spinocerebellum?
Anterior lobe, vermal and paravermal areas of posterior lobe
What parts of cerebellum are pontocerebellum?
Posterior lobe lateral hemisphere
What parts of cerebellum are vestibulocerebellum?
Flocculonodular lobe
What runs in the superior cerebellar peduncle?
Mostly efferent fibers, some afferent from ventral spinocerebellar tract
What runs in the middle cerebellar peduncle?
Afferent fibers contra pontine gray: indirect cortical input from lateral hemisphere post parietal (planning) & motor association cx (executing mvmt)
What runs in the inferior cerebellar peduncle?
Afferent fibers from Clark & acc cun nuc to spinocerebellum, contra ION to entire cerebellum, vest n and nuc to vestibulo; some efferents
What are the afferent inputs to vestibulo, spino, and ponto/cerebrocerebellum?
V: vestibulocerebellar tract, ION
S: spinocerebellar trx, pontocerebellar trx, ION
P: ponto trx and ION
What are the input fibers to cerebellum?
Climbing fibers from ION, mossy fibers
What are the internal circuitry fibers of cerebellum?
Climbing fibers to Purkinje, mossy fibers to granule cells to Purkinje, and interneurons (stellate, basket, Golgi cells)
What are the output fibers of the cerebellum?
Purkinje cells to deep nucleus
Describe the climbing fibers.
Excitatory fibers from ION, via inferior cerebellar peduncle. Activated when errors are made (to correct), synapse on Purkinje dendrites
Describe mossy fibers.
Excitatory. Make up all other cerebellar afferents through all peduncles. Synapse on granule cell bodies and dendrites.
What is the granular layer?
Innermost, with granule cells: small excitatory cells, most cells in cerebellar cortex, input from mossy fibers, output to parallel fibers (to molecular layer). Also has Golgi cells (inh to granule cells)
What is the Purkinje layer?
Middle layer with Purkinje cells: inhibitory, at 90’ to parallel fibers, input from climbing and parallel, output to deep nuclei (main output of cerebellum)
What is the molecular layer?
Outermost, few stellate and basket cells (inh). Primarily axons (parallel, climbing) and dendrites (Golgi, Purkinje)
What are the deep nuclei? Where are they located?
Dentate (lateral), interpositus (emboliform + globus), fastigial (medial); excitatory output, at level of PM junction
What is input to and output from dentate nucleus?
In: lateral hemisphere Purkinje cells (ION climbing, ponto mossy from post parietal)
Out: superior cerebellar peduncle
What is input to and output from interpositus nucleus?
In: paravermal Purkinje (ION climbing, ponto mossy from M1, spinocerebellar mossy proprio)
Out: superior cerebellar peduncle
What is input to and output from fastigial nucleus?
In: vermal Purkinje (ION climbing, spino mossy proprio)
Out: sup and inf cerebellar peduncles
What is input to and output from vestibular nuclei?
In: F-N lobe P cells via ICP (ION climbing, vestibular mossy)
Out: MLF
What efferent fibers are in superior cerebellar peduncle?
Deep nuc to contra red nuc (interpos nuc) to SC, VL/VA thalamus to premotor area (dentate) and M1 (interpos), vestibular nuc/RF to SC (fastigial)
What efferent fibers are in inferior cerebellar peduncle?
Fast nuc -> ipsi vest nuc and RF FN Purkinje (inh) to ipsi vest nuc (up to CN 3,4,6, down to vestibulospinal trx)
What are the four cardinal cerebellar signs?
Ataxia, intention tremor, hypotonia, asthenia (weakness)
What are causes of unilateral cerebellar signs? Bilateral?
Uni: tumor, infarct, trauma, demyelinating disease
Bi: toxic effects, metabolic/nutritional problems, MS
What is posterior lobe syndrome? What are possible causes?
Loss of voluntary mvmt coordination: intention tremor, dysmetria, dysdiadochokinesia, maybe dysarthria
From stroke, trauma, degen disease
What is anterior lobe syndrome? What are possible causes?
Loss of LL coordination: gait ataxia, impaired heel-shin, progresses to UL and dysarthria
From malnutrition, chronic alcoholism
What is flocculonodular lobe syndrome? What are possible causes?
Loss of paraxial mm coordination: truncal ataxia, falling while trying to sit/stand, instability head/neck coord/titubation, nystagmus From tumor (medulloblastoma)
What other functions has cerebellum been controversially linked to?
Higher cognition, emotion/limbic system, attention
What deficits appear with lesions to anterior, posterior, medial, and lateral cerebellum?
Ant: motor
Post: cognition
Med: affective/emotion
Lat: cognition
What are cognitive affective disorders associated with cerebellum lesions?
Executive function (planning, verbal fluency, reasoning, working memory), spatial cognition, language deficits, personality change (blunted or disinhibited)
What are symptoms of midline cerebellar tumor?
Flat affect, inappropriate behavior, perseveration, difficulty making decisions
