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Gross anatomy of cerebellum
- located dorsal to pons and 4th ventricle and medulla
- -separated from overlying cerebral cortex by tentorium cerebelli
- -2 symmetrical halves, partly d ivided by posterior cerebellar incisure (containing a dorsal flap, the falx cerebri)
Major anatomical divisions (flecting functional regions)
- -intermediate hemisphere
- -lateral hemisphere
- folds on terminal folia (equivalent to gyri in cerebral cortex)
- cortex = organized into groups of folia = 10 lobules and 3 lobes
what lobules the cerebellum have?
- total: 10
- Anterior: I - V
- Posterior: VI - IX
- Flocunodular: X
all axons travelling to and from the cerebellum course thru superior, middle, and inferior
Are thye efferents or afferents?
the superior, middle, and inferior of hte cerebellar peduncles
- superior: efferents
- middle: afferents
- inferior: efferents + afferents
deep cerebellar nuclei - key elements of neural circuit
- 4 nuclei:
spinocerebellum; where, control?
- originate in spinal cord to cerebellum
- inputs from sc; controls posture and movement of trunk and limbs; provides some immediate feedback based on sensory input from muscles
- -comprises the vermis + intermediate hemisphere to both anterior and posterior lobes
- -projects thru fastigial and interposed nuclei
- -has somatotropic organization
- have 4 AFFERENT tracts
what are the four spinocerebellar tracts?
- dorsal spinocerebellar tract,
- cuneocerebellar tract,
- ventral spinocerebellar tract,
- rostral spinocerebellar
the dorsal spinocerebellar tract and cuneocerebellar tract travels...
- in ipsilateral lateral column; both enters cerebellum thru ipsilateral inferior cerebellar peduncle
- -sensory info comes from periphery
ventral spinocerebellar tract
- travels after a decussation in ventral portion of hte lateral column and enter cerebellum via superior cerebellar peduncle.
- once in cerebellum fibres cross again; input is ipsilateral
ventral spinocerebellar tract
both relay itnernal feedback signals reflecting amounts of neural activity in descending pathways
input -output organization
- all major inputs feeds to deep cerebellar nuclei as well as cerebellar cortex
- outs thru dcn
- vermis sends efferents thru fastigial n. to...
- 1) inferior cerebellar peduncles -to- medial descending pathways and reticulospinal and vestibulospinal
- 2) inferior cerebellar peduncles -to- VL -to- primary motor cortex descends -to- medial (ventral) corticospinal tract
where does the intermediate hemisphere sends the efferents?
- ..through interposed n. to...
- 1) superior cerebellar peduncle -to- red nucleus (magnocellular) -to- rubrospinal tract
- 2) sperior cerebellar peduncle -to- VL -to- lateral corticospinal tract
cerebrocerebellum does what? locate where? and projects where?
- participates in planning of movement
- -located in lateral hemisphere
- -projects to dentate nucleus
- -this part of the cerebellum is interconnected with the cerebral cortex, rather than receiving its input from spina cord
- AFFERENT input - from entire controlateral cerebral cortex
What is the afferent input?
- 1. contralateral cerebral cortex
- 2. middle pontine n.
- 3. middle cerebellar peduncle
- 4. contralateral cerebellar cortex
- efferent pathway -to- dentate n. to either ...
- 1. red n. (parvocellular) to inferior olivary n. (ipsilateral)
- 2. VL -to- primary motor cortex and premotor cortex & prefrontal cortex ( influences behavior and learning)
vestibulocerebellum; functions, input, located, projects?
- -maintain balance and controlling head and eye movements
- -input from vestibular labyrinth
- -located in floculonodular lobe
- -projects to vestivular nuclei (takes place of DCN)
- afferent input:
- -primary vestibular afferents (only primary sensory n. projects directly to cerebellum)
- -secondary vestibular neurons in vestibular nuclei
- vestibular cerebellar cortex
- vestibular nuclei
- either Med and later VS tracts OR
- Med longitudinal fasciculus (eyes, head)
cytoarchitecture and circuitry of cerebellar cortex
have 3 cell layers
what are the 5 cell types?
- granule cell
- Stellate Cells
- Basket Cells
- Golgi Cells
- inhibitory -GABA
- -contacted by climbing fibres
- -major output neuron (only neuron prjecting outside cerebellar cortex)
- located in PCL (projects to DCN)
- projects to vestibular nuclei thru inferior cerebellar peduncle (icp)
- -contacted by mossy fibres
- -only excitatory neuron
- -puts out just 1 parallel fibre up to molecular layer to purkinje dentrites
- -contact Purkinje cell dendrites (inhibitory)
- locate: outer molecular layer (inhibitory, taurine)
- -contact Purkinje soma (basket around it)
- locate: inner molecular layer (inhibitory, GABA NT)
- -contacts granule cell within glomeruli (inhibitory)
- glial capsule and specificity of connections
- located: granule cell layer (inhibitory, GABA)
where does Clarke's Nucleus and accessory cuneate nucleus relay sensory info to?
to the spinocerebellum
Clarke's nucleus ranges from where?
C8 to L2 within medial portion of intermediate zone
axons in the spinal cord travels...
- in dorsal spinocerebellar tract to icp (medulla)
- from ventral spinocerebellar tract to scp (pons) -[orginate from spinal border cells]