Cerebellum Flashcards
Which sensory inputs do the cerebellum receive from?
Receives input from all sensory systems and from many areas of the brain
Generally, what does the cerebellum aid in?
Control of muscle tone, posture and other aspects of motor activity
Specifically how does the cerebellum aid motor activity?
Helps to synchronize muscle contractions such that the force, range and direction of a movement are coordinated.
Is the involvement of the cerebellum in motor control indirect or direct? Why?
Largely indirect, the cerebellum itself does not directly influence LMNs.
Where do the output neurons of the cerebellum project fibers to?
Project to motor areas of the brain and brainstem that then project descending motor control fibers to LMNs
What are the 2 major regions of the cerebellum?
Vermis
Hemispheres
What is the vermis?
Medial portion, extending from superior surface to inferior surface
How many hemispheres are in the cerebellum?
2, Right and Left
What is the paravermis?
The medial part of the hemispheres
What is the primary fissure of the cerebellum? And where is it located?
On the superior surface that separates the anterior from the posterior lobe
Where is the anterior lobe of the cerebellum?
Anterior to primary fissure on superior surface
Where is the posterior lobe of the cerebellum?
Posterior to primary fissure on superior and inferior surface
Where is the flocculonodular lobe found?
Along anterior edge of inferior surface of cerebellum
How many lobules make up the flocculonodular lobe?
3
What are the lobules that make up the flocculonodular lobe?
2 Flocculi
1 Nodulus
Where are the flocculi found?
Near VII and VIII cranial nerves
Where is the nodule?
Midline suspended or hangs downward in IV ventricle
What are the different parts of the cerebellum?
Archicerebellum
Paleocerebellum
Neocerebellum
What are the parts of the cerebellum based on?
Developmental criteria
What is the archicerebellum associated with?
The vestibular nerve and nuclei
What does the archicerebellum correspond anatomically with?
Flocculonodular
What does the paleocerebellum do?
Receives many of its afferent input from sensory receptors that ascend from the spinal cord
What does the paleocerebellum correspond anatomically with?
Corresponds to the vermis and paravermi
What movements are related to the archicerebellum?
Trunk movement
What movements are related to the paleocerebellum?
Trunk and proximal extremities
What does the neocerebellum do?
The newest and the largest part of the cerebellum. Input is largely from the cerebral cortex after relay in the pontine nuclei
What does the neocerebellum correspond anatomically with?
Corresponds to part of the vermis, but mostly the lateral parts of the hemispheres
What movements are related to the neocerebellum?
Distal extremities and face
What are folia of the cerebellar cortex?
Seies of narrow leaf-like folds
What neuron types are included in the cerebellar cortex?
Purkinje, Golgi, STellate, basket and granule cells
What are the 3 distinct histological layers of the cerebellar cortex?
Molecular layer
Purkinje layer
Grnular layer
What is the molecular layer of the cerebellar cortex?
Outer layer
- includes few neurons (stellate and basket cells)
- serves as an important synaptic field
What is the purkinje layer of the cerebellar cortex?
Middle layer
- single row of purkinje cells
Where do the purkinje cell dendrites stem from?
They arborize in molecular layer
Where do the axons of purkinje cells terminate?
Axons leave cerebellar cortex and terminate on deep cerebellar nuclei or the vestibular nuclear complex
Are purkinje cells efferent or afferent neurons?
Purkinje cells are the efferent neurons of the cerebellar cortex (only neurons to send axons out of the cortical circuit)
What is the granular layer of the cerebellar cortex?
Inner layer
- densely packed neurons include granule and golgi cells
Where do the axons of granule cells ascend and what do they do?
Axons of granule cells ascend into molecular layer and synapses/influences purkinje cells
What part of the cerebellum is made of white matter?
Forms core or medullary center
What are the white matter fibers are continous with?
The 3 pairs of cerebellar peduncles
What does the white matter form when it extends out to the cortex?
Arbor vitae
Are the white matter fibers efferent or afferent from the cerebellum?
Fibers are both efferent and afferent
What two structural types of fibers are afferent fibers to the cerebellar cortex?
Mossy fibers
Climbing fibers
What are mossy fibers?
Fibers that terminate in the granular layer in an expanded terminal called rossette
What types of cells synapse with mossy fibers?
Golgi and granule cells
Where do granule cell axons project?
Project into molecular layer and influence purkinje cells
What type of fibers are most of the afferents to cerebellar cortex?
Mossy fibers
What are climbing fibers?
Fibers that ascend into the molecular layer where they wind or climb along the dendritic trees of purkinje cells
Where do climbing fibers excert control on?
Purkinje cells
Where do climbing fibers originate from?
Climbing fibers originate from the contralateral inferior olivary complex and are primarily olivocerebellar fibers
Where do afferents to the cerebellum traverse?
Traverse the cerebellar peduncles
What type of fibers do the middle cerebellar peduncles include?
Only pontocerebellar fibers
List the pathway from the left cerebral cortex to the right cerebellum
Left cerebral cortex -> left pontine nuclei (via corticopontine fibers) -> right cerebellum (via pontocerebellar fibers)
Where is the archicerebellum anatomically
flocculonodular lobe
Where does the archicerebellum receive input from
receives afferent input from the vestibular nerve, vestibular nuclei, and contralateral inferior nucleus
-these fibers project to the cerebellar cortex and the fastigial nucleus
Where do the purkinje fibers of the archicerebellum send axons to
to the fastigial nucleus and some into the brainstem
What is the efferent output of the archicerebellum by
neurons of the fastigial nucleus
–these efferent fibers traverse cerebellar peduncle and terminate in the vestibular nuclear complex in the brainstem
What is the archicerebellum involved in
- adjustment of muscle tone in response to vestibular data
- maintenance of equilibrium and eye position in response to head movement
What does the paleocerebellum correspond to anatomically
most of the vermis and the paravermis
Where does the paleocerebellum receive input from
- dorsal and ventral spinocerebellar tracts
- cuneocerebellar tract
- olivocerebellar tract
- others
Which side of the paleocerebellum receive sensory input from
ipsilateral side of the body
Where do the purkinje cells of the paleocerebellum project axons
to the fastigial nucleus and the globose and emboliform nuclei
How do the fibers of the festigial nucleus travel
traverse the ICP, terminate in and influence the output of the vestibular nuclear complex
- -vestibulospinal tract
- -MLF
How do the fibers of the globose and emboliform nuclei travel
traverse the superior cerebellar peduncle and terminate
–on UMN’s in the reticular formation and influence output of motor pathways
What does the reticulobulbar tract influence
LMN’s of cranial nerves
Where does the ventral/anterior reticulospinal tract originate
from UMN’s in pontine reticular formation areas
Where does the lateral reticulospinal tract originate
from the UMN’s in medullary reticular formation
What are the 4 pairs of the central nuclei in the medullary center
fastigial nucleus
globose nucleus
Emboliform nucleus
dentate nucleus
What are the 2 sources of input to the central nuclei
most is from purkinje cells of the cerebellar cortex
some from sources outside the cerebellum
How do the axons of the central nuclei project out of the cerebellum
via the inferior and superior cerebellar peduncles
What do the axons of the central nuclei provide
THE final efferent output of the entire cerebellum
