Cerebellum Flashcards
Cerebellum location
posterior cranial fossa
separated from cerebrum by tentorium cerebelli
lies over fourth ventricle
connected to brainstem by 3 cerebellar peduncles
Cerebellum surfaces
Superior: touching tentorium
Inferior: touching inferior cranial fossa
Anterior: touching brainstem
Vermis
midline structure of cerebellum
Folia
extensive folds of cerebellum
Anterior lobe of cerebellum
superior surface
separated from posterior lobe by primary fissure
Flocculonodular lobe
visible on anterior surface
nodule: the most anterior part of vermis, connected to flocculus
Most medial area of inferior surface of cerebellum - sits just above foramen magnum, the cerebellar tonsils
Superior cerebellar peduncle afferents
anterior spinocerebellar tract
acoustic and optic information
Superior cerebellar peduncle efferents
detatorubrothalamic tract
dentatothalamic tract
Middle cerebellar peduncle afferents
Pontocerebellar tract
Inferior cerebellar peduncle afferents
vestibulocerebellar tract
olivocerebellar tract
posterior spinocerebellar tract
Inferior cerebellar peduncle efferents
cerebellovestibular tract
cerebelloolivary tract
Cerebellum function
receives andi nterprets proprioceptive info
coordinates balance (linked to vestibular nuclei)
coordinates fine movement, eye-hand coordination
predicts sensory consequences of movement
coordinator/predictor of cortical output (movement and cognition)
information sent to cerebellum can be used for skilled manipulation of muscles and mental concepts
Same consistent wiring, with differnet types of cnonections
outflow through segregated fibers
Homunculus on cerebellum
Trunk always in midline on vermis
extremities on cerebellar hemispheres
Anterior lobe: extremities
Posterior lobe: mirror image representations of both head and extremities
Archicerebellum
vestibulocerebellum
flocculonodular lobe (and vermis)
trunk control
Paleocerebellum
spinocerebellum
vermis and anterior lobe
synergistic movement of extremities
Neocerebellum
Cerebrocerebellum
posterior lobe
topographical representation of extremities
areas for eye movement
speech coordination of intricate and complex movements
Vestibulocerebellar connections
Afferents from vestibular nuclei –> paravermis, flocculonodular lobes
Efferent to fastigial nucleus
Bilateral projections to vestibular nuclei and reticular formation
Information projects through vestibulospinal/reticulospinal tracts to spinal cord motor neurons
Vestibulocerebellar fxn
adjust axial stability and balance
provide information of position of head and body in space
help orient eye movements during locomotion (vestibulo-ocular reflex)
Spinocerebellar connections
Muscle spindles/Golgi tendon organs (where/how the limbs are positioned)–> dorsal spinocerebellar tract through ICP
Spinal border cells in anterior horn of spinal cord (copy of movement command that went to LMNs) –> ventral spinocerebellar through SCP
Terminate in anterior lobe (limbs) and vermis (trunk)
Spinocerebellar fxn
proprioceptive information enters cerebellum
information goes to all players involved in movement
feedback to spinal cord and to cortex
correction and fine-tuning of ongoing movement patterns
Cerebrocerebellar connections
Cortex –> pontine nuclei –> cerebellar hemispheres (pontocerebellar tract through MCP), cross over to contralateral side
Additional afferent information from the contralateral olivary nuclear complex
Feedback to red nucleus, thalamus, cortex
Red nucleus: major relay nucleus
Olives: project to all of cerebellum, receive input from all loops, calculate feed forward loops
Reciprocal connections in cerebrocerebellar connections
Output from neocerebellar cortex mainly to dentate nucleus –> red nucleus –> VL of thalamus (dentatorubrothalamic tract)
Direct projections from dentate nucleus –> thalamus (dentatothalamic tract)
Thalamus –> projects back to motor/sensory areas of cortex
Midline cerebellar disease
gait difficulty truncal imbalance wide-based irregular steps veers to one side abnormal head postures head tilt oculomotor dysfunction nystagmus
Flocculonodular lobe syndrome
most commonly seen in children with a medulloblastoma
Truncal ataxia –> inability to stabilize/balance axial musculature - wide-based stance as well as swaying
Nystagmus - damage to vestibuloocular pathways
Lateral cerebellar disease
Hypotonia - decreased resistance to passive movement
Dysarthria
Limb ataxia - dysmetria, decomposition, dysdiadochokinesia
Intention tremor - irregular, rhythmic tremor that increases as patient approaches a target
Impaired check
Oculomotor disorders
Posterior lobe syndrome
areas for eye movement and speech –> cerebellar mutism
Coordination of intricate/fine movements
most commonly seen in:
- demyelinating diseases (MS)
- midbrain infarctions affecting dentatorubrothalamic tract (cerebellar efferent)
- infarcts to cerebellar hemispheres
Deficits in hand-eye coordination, dysmetria, dysdiadochokinesia
typical language disorders characterized by linguistic incoordination –> inability to use grammar/syntax
Lesions to anterior lobe
spinocerebellar input
gait ataxia
Ethanol - cerebellum
toxic to Purkinje cells in cerebellar cortex
anterior lobe most affected
usually reversible
permanent damage possible in chronic alcoholics
leads to gait ataxia
Anterior inferior cerebellar artery supply
all cerebellar peduncles
flocculus
all deep cerebellar nuclei
Posterior inferior cerebellar artery supply
inferior 2/3 of posterior lobe
tonsils
nodulus
superior cerebellar artery supply
anterior lobe
superior 1/3 of posterior lobe
vermis
