CEREBELLUM Flashcards
ROLE OF THE CEREBELLUM:
Cerebellum controls the maintenance of balance, influences posture & tone and coordinates movement.
- Cerebellum compares and integrates afferent information from the periphery with plans for action received from the cortex to produce efficient, smooth movements.
OVERALL STRUCTURE OF THE CEREBELLUM:
- 3 cerebellar lobes: anterior, posterior, flocculonodular.
- 3 cerebellar peduncles: inferior, middle, superior.
- 4 deep cerebellar nuclei:
1. dentate, (LATERAL)
2. fastigial, (MEDIAL)
3.emboliform
4. globose.
UNDERSTANDING THE DEEP CEREBELLAR NUCLEI
- Relay stations.
- Efferent Purkinje fibres (from the cerebellar cortex) project to the deep cerebellar nuclei.
- Efferent fibres from deep cerebellar nuclei HEAD TO THALAMUS, RED NUCLEI AND VESTIBULAR NUCLEI
TO AFFECT MOVEMENT
Pathway to and from Deep cerebellar nuclei
- Peripheral NS
- CEREBELLUM; VIA PURKINJE FIBRES
- CEREBELLAR NUCLEI (FIBRES)
- THALAMUS, RED NUCLEI, VESTIBULAR NUCLEI
- AFFECT MOVEMENT
UNDERSTANDING INFERIOR OLIVARY COMPLEX
- PURPOSE: Helps coordinate motor output.
- Receives afferents from the MOTOR AND SENSORY CORTICES of the cerebral hemisphere & from RED NUCLEUS of the midbrain.
- Olivocerebellar fibres = Climbing fibres.
- Climbing fibres project to cerebellum via INFERIOR CEREBELLAR PEDUNCLE
- and SYNAPSE in DENTATE NUCLEUS and upon Purkinje cells of the cerebellar cortex.
INFERIOR OLIVARY NUCLEUS COMPLEX (AFFERENT MODEL) PATHWAY
AFFERENTS:
1. MOTOR + SENSORY CORTICES OF CEREBRAL HEMISPHERES
2. RED NUCLEI OF MIDBRAIN
OLIVOCEREBELLAR TRACTS (climbing fibres project to)
CEREBELLUM via INFERIOR PEDUNCLE
SYNAPSE IN: DENTATE NUCLEUS UPON PURKINJE CELLS OF CEREBELLAR CORTEX
OTHER AFFERENTS TO CEREBELLUM
- All other afferents to cerebellum = end as MOSSY FIBRES.
(Pontocerebellar, spinocerebellar & vestibulocerebellar fibres) - Carry vestibular, proprioceptive and cortical information
SPINAL CORD VS CORTEX PATHWAY TO CEREBELLAR CORTEX
CORTEX –> PONTINE NUCLEUS —> CEREBELLAR CORTEX
OR
SPINAL CORD OR OLIVE OR VESTIBULAR NUCLEI —>
CEREBELLAR CORTEX
UNDERSTANDING EFFERENTS OF THE CEREBELLUM
1 * Efferent information RELAY through DEEP NUCLEI
2 * DENTATE NUCLEUS project to CORTEX AND RED NUCLEUS
3* Efferents from the EMBOLIFORM, FASTIGIAL AND GLOBOSE nuclei project to RED NUCLEUS AND OLIVARY NUCLEAR COMPLEX
- Efferents from FLOCCULONDULAR LOBE project to VESTIBULAR NUCLEI
EFFERENTS OF THE CEREBELLUM
- CEREBELLAR CORTEX;
- RED NUCLEI, VESITIBULAR CORTEX, OLIVE
- RED NUCLEI TO THALAMUS VL/VA
Cerebrocerebellar/Pontocerebellar afferents ultimately modulate activity of the corticospinal tract.
ROLE :
* Coordinates & streamlines motor output from cortex.
HOW?
* Efferents from CORTEX TO PONTINE NUCLEI
- PONTOCEREBELLAR AFFERENTS : POINTINE NUCLEI TO CEREBELLAR CORTEX
- Purkinje fibre to dentate nucleus.
- Dentothalamic fibres: dentate nucleus to VL nucleus of thalamus.
- Thalamocortical neurons project to PRIMARY MOTOR CORTEX
Spinocerebellar afferents ultimately affect activity of the rubrospinal tract.
HOW?
1 * Spinocerebellar afferents project to CEREBELLAR CORTEX
- Purkinge cell efferents project to GLOBOSE AND EMBOLIFORM NUCLEI
- G&E nuclei project to red nucleus (+ vestibular nuclei + reticular formation) to modulate activity of rubrospinal & vestibulospinal tracts
ROLE: coordinate limb movements.
Vestibulocerebellar afferents ultimately affect activity of the vestibulospinal tract.
- Vestibulocerebellar afferents project to cerebellar cortex.
- Purkinje cell efferents project to FASTIGIAL NUCLEI
- Fibres from fastigial nuclei project to VESTIBULAR NUCLEI AND RETICULAR FORMATION
ROLE: to coordinate adjustment of truncal stability & balance.
Cytology of the cerebellar cortex
molecular layer
* Golgi cells
* Granule cells
Purkinje layer
* Purkinje cells
Granule cell layer
* Stellate cells * Basket cells
* Mossy fibres
* Climbing fibres
white matter
UNDERSTANDING THE WIRING OF CEREBELLAR CORTEX
INPUT:
CEREBELLAR AFFERENTS
MOSSY FIBRE
CEREBELLAR GLOMERULUS
GOLGI CELL
GRANULE CELL
PURKINJE CELL
OR
OLIVE
CLIMBING FIBRE
PURKINJE CELL
OUTPUT:
STELLATE CELL AND OR BASKET CELL TO PURKINJE CELL
- CEREBELLAR OUTPUT
- Afferent mossy fibres synapse on granule & golgi cells which “screen” information before it is passed on to the Purkinje cells.
- Afferent climbing fibres pass directly to synapse on Purkinje cells.
- Purkinje cells send inhibitory output to the deep cerebellar nuclei.
