Cerebellum Flashcards
What is the cerebellum responsible for?
-Motor area of the brain maintaining equilibrium and muscle contractions
-Ensures that the contraction of the correct muscle occurs at the right time with correct force
-Plays a role in learning patterns of neuronal activity for carrying out movement
-may have sensory and cognitive functions
Describe the connections of the cerebellum
-Cerebellum receives input from regions of cerebral cortex that plan and initiate skilled movements
- Also receives information from sensory systems that monitor course of movements
-Computes a “motor error” from these inputs
-Corrects output of motor cortex via its thalamic connections – does not project to LMN in BS or SC
-Corrections occur in real time, but also over longer periods, as in motor learning
-Major afferent and efferent pathways form a loop between the cerebral cortex, brainstem and spinal cord
What is the 2 major anatomical divisions of the cerebellum?
-cerebellar cortex
-deep cerebellar nuclei
What are the constitutes of the cerebellar cortex?
-Pontocerebellum
-Spinocerebellum
-Vestibulocerebellum
What constitutes the deep cerebellar nuclei
-Dentate nucleus
-Interposed nuclei
-Fastigial nucleus
what are the lobes of the cerebellum?
-flocculonodular
-anterior
-posterior
What are the layers of the cerebellar cortex?
3 cortical layers:
-molecular
-Purkinje cell
-granule cell
Describe the granule cell glomeruli
-mossy fibres synapse with neurons in the granule layer to form glomeruli
what are the major tracts of the cerebellum?
-3 major tracts (peduncles):
–superior
–middle
–inferior
describe the superior peduncle of cerebellum
-afferent input from sc, colliculi
-efferent output to the UMN in sup.
colliculus and M1 (area 4) & PMA
(area 6), via ventral lateral thalamus
describe the middle peduncle of the cerebellum
-afferent input from the pontine nuclei
Describe the inferior peduncle of the cerebellum
-afferent input from inferior olive, sc, vestibular nerve
-efferent to the vestibular nuclei and reticular formation
what is the structural anatomy of the cerebellum
-flocculonodular lobe
-vermis, paravermis
-lateral hemispheres
what is the phylogenetic anatomy of the cerebellum
-archicerebellum
-paleocerebellum
-neocerebellum
what is the function anatomy of the cerebellum?
-vestibulocerebellum
-spinocerebellum
-pontocerebellum
Describe the Vestibulocerebellum
-Occupies the flocculonodular lobe (flocculus and nodule of vermis)
-Input from vestibular nuclei, vestibular organs (position and movement of the head)
-Output directly back to them via the fastigial nucleus
-Influences motor activity via the vestibulospinal tract, reticulospinal tract and the medial longitudinal fasciculus
-Functions in maintenance of balance, co-ordination of head & eye movements
describe the spinocerebellum
-Paravermis and vermis (except the nodule)
-Input spinal cord (esp. dorsal & ventral spinocerebellar tracts, cuneocerebellar tracts and trigeminal nucleus), visual, auditory and vestibular systems, motor and premotor cortices
-Outputs via the interposed and fastigial nuclei to reticular formation, vestibular nuclei, motor nuclei of cranial nerves, red nucleus, via thalamus to cortex
-Regulation of posture & movements under continuous sensory control
describe the pontocerebellum
-Lateral cerebellar hemispheres.
-Input from neocortex, from all motor and somatosensory areas and association cortex via the pontine nuclei, some from visual cortex and limbic system
-output is through the dentate nucleus, to motor and premotor cortex via the thalamus (VL), the red nucleus of the midbrain
-Influences corticospinal, corticoreticular and reticulospinal pathways
-Initiation, execution of preprogrammed rapid movements, co-ordination of fine movement
What is cerebellar ataxia
-damage to the cerebellum produces jerky, imprecise movements
-ipsilateral nature of symptoms
-somatotopy results in regional specificity of symptoms
What is nystagmus?
-vestibulocerebellum damage
-inability to stand upright
what is dysmetria?
-dysmetria
-abnormal gait
-action tremors
what happens with pontocerebellum damage?
impairments in highly skilled movements
