Lecture 14-Cerebellum Flashcards
What are the gyri of the cerebellum called? What does the cerebellar cortex surround? What is found deeply in the cerebellum?
Gyri of cerebellum = folia
Surrounds arbor vitae (tree of life) white matter tracts
Deep cerebellar nuclei found in central white matter
What is the role of the deep cerebellar nuclei?
The deep cerebellar nuclei process and relay information between the cerebellar cortex and other brain regions via the cerebral peduncles.
Anatomy of Cerebellum:
1) 2 hemispheres divided by vermis
2) 3 lobes -anterior, posterior, flocculonodular
3) The cerebellar cortex is on the outside, covering the white matter located on the inside.
Three Functional Subdivisions of the Cerebellum
1) Cerebrocerebellum
(lateral hemisphere) -posterior lobe -Neocerebellum -newest
2) Spinocerebellum (vermis and intermediate) -anterior lobe-Paleocerebellum-middle
3) Vestibulocerebellum
(flocculonodular lobe) -Archicerebellum (oldest)
How many cell types does the cerebellum have? Name them. Which of these cell types have the biggest somas? The smallest somas?
- Outer stellate
- Basket
- Purkinje (biggest somas)
- Granule (smallest somas)
- Golgi
- Unipolar brush
What are the three layers of the cerebellar cortex? Name the cells that are present in each layer.
- Granular layer (inner): granule, Golgi, & unipolar brush cells
- Purkinje layer (middle): Purkinje cells
- Molecular layer (outer): basket & outer stellate cells
What layer are granule cells found in the cerebellum? Are they excitatory or inhibitory? Where are the dendrites of the granule cells found? Where does its axons rise up to? What do these axons eventually become?
Granular layer → excitatory
Dendrites found within the glomeruli w/inputs from Golgi cells & mossy fibres
Axons rise to molecular layer, turn 90 degrees, & become parallel fibres to run perpendicular to folia axis
What layer are Golgi (inner stellate) cells found in the cerebellum? Are they excitatory or inhibitory?
Granular layer → inhibitory
Where are the dendrites of the Golgi cells found? Where do the dendrites receive their inputs from? Where are its somas found?
Dendrites in all three layers
Dendrites receive input from granule cells, mossy & climbing fibres
Somas found in glomeruli
Where are the arborizing dendrites found for the Purkinje cells in the Purkinje layer? Where do they project to?
- Dendrites in molecular layer, perpendicular to folia axis
- Project to deep cerebellar nuclei & some vestibular nuclei in the brainstem, making them the only extracerebellar projection from the cerebellar cortex.
What layer are the basket & outer stellate cells found in the cerebellum? Where do they project their inhibitory synapses to? What are they excited by?
Molecular layer
Inhibitory synapses onto Purkinje cells
Excited by parallel fibres of granule cells
What are the four deep cerebellar nuclei? Which of these nuclei make up the interposed nuclei?
- Dentate
- Emboliform
- Globose
- Fastigal
Emboliform & globose make up interposed nuclei
What are the three main zones of the cerebellar cortex? Where does each project to?
- Vermal zone projects to fastigial nucleus
- Paravermal zone projects to interposed nuclei
- Hemispheric zone projects to dentate nuclei
Where does the flocculonodular lobe (vestibulocerebellum) get direct projections from as its input?
Projections from vestibulocochlear nerve (CN VIII) & 2nd-order projections from vestibular nuclei →via the inferior cerebellar peduncle (vestibulocerebellar fibres)
Where does the flocculonodular lobe (vestibulocerebellum) project its output to? What structure does it go through?
Projects to vestibular nuclei → goes through superior cerebellar peduncle (fastigiovestibular tract)
What does the flocculonodular lobe (vestibulocerebellum) influence? How does it do this?
Influences vestibulospinal tract (posture, balance, head movement) →vestibular projections to MLF involved in coordinating head & eye movements
Where does the anterior lobe (spinocerebellum) get projections from as its input? From what structure?
Input projections from spinocerebellar, cuneocerebellar, & trigeminocerebellar tracts → inputs via inferior cerebellar peduncle
What is the main role of the anterior lobe (spinocerebellum)?
Proprioceptive info of stereotyped movements ( repetitive and predictable body movements)
What parts/areas of the cerebellum are responsible for the trunk/head & the distal limbs?
Vermis controls trunk/head for vermis and paravermal zone controls, distal limbs
Where does the posterior lobe (cerebrocerebellum) receive its inputs from?
Received pontocerebellar fibre inputs via middle cerebellar peduncle
Where does the posterior lobe (cerebrocerebellum) project to?
Projects via superior colliculus back to cortex and other brainstem areas
What is the role of the posterior lobe (cerebrocerebellum)?
Information about planned and ongoing voluntary non-stereotyped movements (e.g reaching for an object, writing, dancing)
What are most inputs to the cerebellum coming in as? What do they release? Are they excitatory or inhibitory?
Most inputs to cerebellum are MOSSY FIBRES releasing GLUTAME → excitatory
Explain the direct & indirect path of mossy fibres that leads to output.
Direct: synapses w/ deep cerebellar nuclei for EXCITATORY output
Indirect: synapse onto Purkinje (& other) cells in cortex, then synapses onto nuclei to INHIBIT output
List the major input, cerebellar cortical zone(s), deep nuclei involved, & descending system(s) for the ANTERIOR LOBE (SPINOCEREBELLUM)
Major input: spinal cord
Cerebellar cortical zones: vermis & paravermal
Deep nuclei: fastigial (vermis) & interposed (paravermal)
Descending systems: medial (vermis) & lateral (paravermal)
List the major input, cerebellar cortical zone(s), deep nuclei involved, & descending system(s) for the POSTERIOR LOBE (CEREBROCEREBELLUM)
Major input: cerebral cortex
Cerebellar cortical zone: hemispheric
Deep nuclei: dentate
Descending system: lateral & motor planning
List the major input, cerebellar cortical zone(s), deep nuclei involved, & descending system(s) for the FLOCCULONODULAR LOBE (VESTIBULOCEREBELLUM)
Major input: vestibular receptors
Cerebellar cortical zone: flocculonodular lobe
Deep nuclei: vestibular nuclei
Descending system: lateral( balance and posture) and medial ( control
of neck muscles
What are the two main destinations for outputs from the cerebellum?
- Purkinje cells (to vestibular nuclei from flocculonodular lobe)
- Deep cerebellar nuclei
What are the components of the medial descending system, and what functions do they influence?
The medial descending system includes the reticulospinal and vestibulospinal tracts, which play a role in posture, balance, and muscle tone.
How does the medial descending system connect to the oculomotor system?
The medial descending system has upward connections via the Medial Longitudinal Fasciculus (MLF) to the oculomotor system, which helps in coordinating eye movements.
What does the lateral descending system consist of, and what functions does it primarily affect?
The lateral descending system includes the rubrospinal and lateral corticospinal tracts, which are involved in fine motor movements, particularly those related to distal limbs.
Where does the primary output of the cerebellum go to? List the output projection path for it.
Ventrolateral nucleus of the thalamus → MI & PMC → corticospinal tract
What layer are unipolar brush cells found in the cerebellum? Are they excitatory or inhibitory? What part of the cerebellum are they found in? What do they synapse with? What functions are they “possibly” responsible for?
Granular layer → excitatory
Found in flocculonodular lobe & vermis → synapse w/ Golgi & granule cells
Responsible for posture, eye movements, vestibuloocular reflexes
What are the two structures that each deep cerebellar nuclei has projections to?
- Inferior olivary nucleus (inferior olive)
- Reticular formation
Function of Anterior Lobe
Involved in motor planning, coordination of voluntary movements, through recieving proprioceptive information.
Function of Flocculonodular Lobe:
Vestibular functions, including balance, spatial orientation, gaze stabilization, and coordination of eye movements during head motion.
