Cerebellum Flashcards
What’s the general/broad function of the cerebellum?
Coordination: correction of current movements to match
those intended
What afferent input does the cerebellum receive?
- Vestibular
- Proprioceptive and skin
- Receptor info
- Sensorimotor cortex
- Auditory system
- Visual system
Where is cerebellar information processed just prior to leaving?
Cerebellar nuclei
What are the names of the types of fibers that enter the cerebellum?
Mossy and climbing fibers
What cells project from the cerebellar cortex to deep nuclei?
Purkinje cells
What motor systems receive output from the cerebellum?
Does the cerebellum directly communicate w/the spinal cord?
- Vestibular nuclei
- *Thalamus
- Red nucleus (reticular formation)
(*no direct connection to sc)
How is the cerebellum related to the ventricular system?
It’s the roof over the 4th ventricle
What is the role of each cerebellar peduncle?
- Inferior and medial peduncles carry info in
- Superior peduncle sends info out
(more info in than out, therefore it’s doing incredible amount of processing)
About what percentage of neurons in the brain are found in the cerebellum?
70-80%
What’s found b/w the cerebellum hemispheres?
Vermis
What does the primary fissure of the cerebellum divide?
Poster and anterior lobes
Where is the flocculonodular (FN) lobe found?
Anterior inferior surface of cerebellum
What does the horizontal fissure of the cerebellum divide?
The posterior lobe, parallel to the primary fissure
What area provides info to the middle cerebellar peduncle?
Cerebral cortex -> pontine nuclei -> MCP
What do climbing fibers, coming into the cerebellum, project from?
Mossy fibers?
- Inferior olives
- Everything else
What movements does the midline vermis of the cerebellum mostly coordinate?
Trunkal movements (balance, gait)
What movements do the hemispheres of the cerebellum mostly coordinate?
Limbs (motor)
What movements does the FN lobe of the cerebellum mostly coordinate?
Vestibular and eye movements (therefore CN output to III, IV, VI)
What afferents come in thru the ICP?
What’s the 1 efferent that comes out?
- Inferior olivary nucleus, vestibular nuclei, sc, trigeminal nuclei, reticular formation
- Vestibular nuclei
What’s the 1 afferent thing that comes into the SCP?
VSCT
Where do cerebellar efferents originate?
*Deep cerebellar nuclei
Lesion of the right cerebellar hemisphere causes problem on ______ side of the body, lesion on right cerebral cortex causes lesion on ______ side of the body
- Right
- Left
After receiving primary vestibular afferents, the FN lobe communicates w/what cerebellar nuclei?
Fastigial and vestibular nuclei
What nuclei does the cerebellar vermis communicate w/?
Fastigial, globose, emboliform, vestibular, and red nuclei
Descending tracts from the red nucleus form what tract?
What’s its function?
Rubrospinal tract
- Balance/coordination (not really important for humans)
What brain areas/nuclei are involved w/the cerebellar hemispheres?
*Dentate nucleus, red nucleus, VL of thalamus, inferior olive, pontine nuclei
What are the cerebellar layers, superficial to deep?
- Molecular layer
- Purkinje cell layer
- Granular cell layer
- White matter
What is mainly contained in the molecular layer of the cerebellum?
What 2 types of cells can be found there (and where do each synapse)?
- Axons and dendrites
- Basket cells (synapse on Purkinje body)
- Stellate cells (synapse on Purkinje dendrites)
What is specifically found in the Purkinje cell layer?
Only axons that leave the cerebellar cortex
What is found in the granular layer?
Granular cells
How do granular cell axons appear after leaving the granular layer?
Appear as parallel fibers
What is deep to the granular cell layer in the cerebellum?
White matter
Where do climbing fibers synapse before reaching purkinje cells?
They don’t
Where do mossy fibers synapse before reaching purkinje cells?
Synapse at granular layer, which sends off granular cell axons as parallel fibers. These fibers reach the purkinje cells.
How many parallel fibers interact w/1 purkinje cell?
How many climbing fibers interact w/1 purkinje cell?
- Thousands
- One
What type of output do Purkinje cells have? (inh or excitatory?)
Inhibitory
Explain the pw of a mossy fiber, in to and out of the cerebellum.
- Mossy fibers come in thru mid/inf peduncles
- Synapse at granular cell layer
- Granular layer sends axons to molecular layer in parallel,
[4. Basket cells (synase at body) and stellate cells (synapse at dendrites) of molecular layer synapse on Purkinje cell layer as well] - Purkinje cell layer can leave cerebellar cortex, synapse on deep cerebellar nuclei
- Axons synapse at nuclei and leave via sup peduncle
Explain the pw of a climbing fiber, in to and out of the cerebellum.
- Climbing fibers come in thru inf peduncles
- Synapse directly at Purkinje cell layer
- Purkinje cell layer can leave cerebellar cortex, synapse on deep cerebellar nuclei
- Axons synapse at nuclei and leave via sup peduncle
What’s a quick easy test to test cerebellar function?
Finger-to-nose (w/eyes closed)
What are some sx of a cerebellar deficit? (video)
Jerky eye movements, loss of fine/controlled movements, walks w/legs spread apart
What’s a cerebellar tonsil?
The inferior lobe of the cerebellum found beneath the FN lobe.
[Chiari malformation is a general term used to describe a condition when the bottom part of the cerebellum (the “tonsils”) dip down into the upper spinal canal.]
Does the cerebellar cortex typically inhibit or excite the dentate nucleus?
Inhibits
What major brain areas does the dentate nucleus directly interact with?
- Red nucleus of brainstem
- Thalamus
Define dystonia.
Involuntary muscle contractions that cause repetitive or twisting movements.
What types of abnormalities usually cause a dystonia?
What’s a possible tx?
- Abnoralities w/in the basal ganglia.
- Botulism toxin
