Cerebellum Flashcards
What information does the cerebellum process and for what purpose?
Unconscious proprioceptive and tactile information to maintain equilibrium and muscle contractions for voluntary movements
Where are the 4 pairs of deep cerebellar nuclei located?
Corpus Medullares (white matter)
What are the 4 pairs of deep cerebellar nuclei?
Fastigial nucleus, Globose nucleus, Emboliform nucleus, Dentate nucleus
Which of the deep cerebellar nuclei run through the inferior cerebellar peduncle?
Fastigial nucleus and medial part of Globose nucleus
Which of the deep cerebellar nuclei run through the superior cerebellar peduncle?
Lateral part of Globose nucleus, Emboliform nucleus and Dentate nucleus
Which deep cerebellar nuclei has vestibular system connections?
Fastigial nucleus
What are the afferent tracts/fibers that run through the inferior cerebellar peduncle?
Dorsal spinocerebellar Tract (DSCT) Direct arcuate fibers Trigeminocerebellar tract Arcuocerebellar fibers Reticulocerebellar fibers Olivocerebellar fibers
What tract conveys unconscious, proprioceptive info to the cerebellum about the lower half of the body and LE?
Dorsal spinocerebellar tract (DSCT)
What fibers convey unconscious, proprioceptive info to the cerebellum about the upper half of the body and UE?
Direct arcuate fibers (aka cuneocerebellar tract)
What tract conveys general proprioceptive info about the head to the cerebellum?
Trigeminocerebellar tract
What is the critical link between the extrapyramidal system and the cerebellum?
Central tegmental fasciculus
What fibers form the middle cerebellar peduncle?
Pontocerebellar fibers
What tracts run through the superior cerebellar peduncle?
Ventral spinocerebellar tract and the trigeminocerebellar tract
What tract conveys unconscious, proprioceptive info from the lumbosacral levels to the cerebellum?
Ventral spinocerebellar tract (VSCT)
What layers make up the cerebellar cortex from deep to superficial?
Granular layer
Purkinje cells
Molecular layer
All information entering the cerebellar cortex eventually converges upon what?
Purkinje cells
What are the only EFFERENTs from the cerebellar cortex?
Purkinje cells
Where do the purkinje cells terminate?
Deep cerebellar nuclei
What are the only EXCITATORY neurons in the cerebellar cortex?
Granule cells of the granular layer
Most cerebellar afferents terminate where?
On to the granule cell’s dendrites
When a cerebellar afferent terminates on to a granule cell, what is the synaptic complex called?
Cerebellar glomerulus
Once granule cells ascend to the molecular layer, what are they called?
Parallel fibers
What are the 2 neuron types in the granular layer of the cerebellar cortex?
Granule cells and Golgi Cells
What are climbing fibers?
The most DIRECT Afferents to the cerebellar cortex
What is the effect the climbing fibers have?
Excitatory on the purkinje cells
Describe the climbing fibers circuit
Inferior olivary nucleus -> Olivocerebellar tract
- Once on the olivocerebellar tract, the fibers become climbing fibers
- They excite the purkinje cells directly
- The purkinje cells then send signals to the cerebellar nuclei to send efferents out
What are mossy fibers?
Most afferents to the cerebellar cortex
What is the effect the mossy fibers have?
Excitatory
Describe the granule cell circuit
Mossy fibers (afferents) go to the cerebellar glomerulus
- Granule cells then ascend and become parallel fibers
- They excite the purkinje cells
- Then the purkinje cells send signals to the cerebellar nuclei to send efferents out
What cell’s axons can INHIBIT the granule cells near the cerebellar glomerulus and stop them from sending afferents to the purkinje cells?
Golgi cells
What is the purpose of the golgi cells?
Modify info entering the granule cell circuit
What do unilateral lesions of the cerebellum normally result it?
IPSILATERAL deficits
Ataxia
Broad-based, staggering gait
Dysmetria
“Missing the mark”
ex. eyes closed, trying to touch ones own nose and miss completely
Dysdiadochokinesia
inability to perform rapidly alternating movements such as pronation - supination
Intention tremor
When reaching for an object, the tremor worsens but is not present when patient is at rest
Decomposition of movement
Movements performed using 1 joint at a time - looks like a robot
Where do lesions resulting in an intention tremor tend to be located?
Dentate nucleus or superior cerebellar peduncle
What does chronic alcohol use due to the cerebellum?
Atrophies the anterior lobe of the cerebellum resulting in severe ataxia of the LE and trunk
Severe ataxia from anterior lobe atrophy due to alcohol may be seen in conjunction with which syndrome?
Korsakoff’s syndrome (memory disorder from alcohol use; includes a vitamin B-1 deficiency)
What sends efferents to the out of the cerebellum?
Deep cerebellar nuclei
