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Neuro - Cerebellum


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Primary functions of cerebellum?
Posture and balance, muscle tone, coordination of voluntary motor activity, learning of repeated motor functions
Major cerebellar pathway?
PURKINJE cells of cerebellar CORTEX -> cerebellar nuclei (e.g. DENTATE nuc) -> thru sup cerebell peduncle to contralateral VL (via dentothalamic tract) -> to primary MOTOR CORTEX of precentral gyrus -> to PONTINE nuclei (as corticopontine tract) -> to contralat cerebellar CORTEX (as pontocerebellar tract), and terminate as MOSSY FIBERS
Three cell layers of cerebellar cortex?
1. Molecular layer (outer)
2. Purkinje cell layer (middle)
3. Granule layer (inner)
Input cerebellar peduncles?
2 types of cerebellar input fibers?
Mossy, climbing
Mossy fibers bring input from where? Excitatory or inhibitory? What do they terminate on?
From pons (pontocerebellar), spinal cord (spinocerebellar), and vestibular nuc (vestibulocerebellar tracts); EXCITATORY; synapse on granule cell dendrites (which excite via parallel fibers)
Climbing fibers bring input from where? Excitatory or inhibitory? What do they terminate on?
From contralat inferior olivary nuc (olivocerebellar tract); EXCITATORY; terminate on cerebell nuc and purkinje dendrites
Output cerebellar peduncle?
SCP (from deep cerebellar nuclei: fastigial, interpositus, dentate)
Output cerebellar fibers? Type of NT?
Purkinje cell axons; GABA
Where do Purkinje fibers project to?
Cerebellar nuclei, vestibular nuclei
What is anterior vermis syndrome? Common cause? Symptoms?
-atrophy of ant lobe (leg region)
-caused by etoh abuse
-sx: gait, trunk, leg DYSTAXIA
What is posterior vermis syndrome? Cause? Symptoms?
-usu. caused by tumor in flocculonodular lobe, often in children
-sx: truncal DYSTAXIA
Triad of cerebellar dysfunction
HYPOTONIA (floppy, rag-doll, pendular reflexes)
DYSEQUILIBRIUM (gait and trunk dystaxia)
DYSSYNERGIA (loss of coordinated muscle activity)
Types of DYSSYNERGIC symptoms
dysmetria (inability to accurately control range of motion), INTENTION tremor, failure to check mvts, coarse nystagmus, dysdiadochokinesia (can't 'screw in lightbulb'), scanning dysarthria (difficulty articulating)
Types of cerebellar tumors? (mostly in kids)
1. astrocytomas (cerebellar hemisphere, good prognosis)
2. medulloblastomas (malignant, from granule layer, cause hydrocephalus)
3. ependymomas (often in 4th ventricle, cause hydrocephalus)
What type of fibers excite Purkinje cells directly?
Climbing fibers
What type of fibers excite Purkinje cells indirectly?
Mossy fibers (via granule cell/parallel fibers)
What are the 3 types of local circuit neurons in the cerebellum? Are they excitatory or inhibitory?
basket cells, stellates, cells, and Golgi type II cells

all are inhibitory, use GABA
What two places do fibers leaving the superior cerebellar peduncle synapse?
Red nucleus (and then descends as rubrospinal tract) and VL thalamus (to cortex, which then descends as corticopontine fibers or corticospinal fibers)
Does a lesion of the cerebellum cause ipsilateral or contralateral cerebellar deficits?
Does a lesion of the red nucleus cause ipsilateral or contralateral cerebellar deficits?
Does a lesion of the VL cause ipsilateral or contralateral deficits?

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