Cerebellum Flashcards
Cerebellum functions
. Equilibrium and coordination of eye movements
. Maintenance of muscle tone and posture
. Coordination and adjustments of motor movements
. Planning and programming of voluntary movements
. Learning of movements
Cerebellum assists in movement of the ipsilateral or contralateral side?
Ipsilateral
Cerebellar fissures
. Primary
. Posterolateral
Cerebellar lobes
. Ant lobe: ant. Primary fissure
. Post. : post, to primary and posterolat. Fissures
. Flocculonodular: ant. To posterolat. Fissure, small and inconspicuous
Cerebellar peduncles
. Inf.: afferents from spinal cord and inf. Olive, some efferents mainly to vestibular nuclei and brainstem reticular formation
. Middle: afferents from pontocerebellar projections of contralat. Basilar pontine nuclei
. Sup: efferents from deep cerebellar nuclei to thalamus (VL) and red nucleus, some afferent from ventral spinocerebellar tract
Layers of cerebellar cortex
. Molecular
. Purkinje
. Granular
Molecular layer
. Cell free area
. Most superficial
. Primarily contains purkinje cell dendrites and axons or granular cell (parallel fibers) and small interneurons
Purkinje cell layer
. Purkinje cell is only neuron to project out of cerebellar cortex
. Project to deep cerebellar nuclei
. Cells have elaborate dendritic trees
Granular cell layer
. Granule cells that function as interneurons
. Excite purkinje neurons
. Give rise to parallel fibers that synapse on purkinje cell dendrites in molecular layer of cortex
. 1 purkinje cell receives input from 100,000 granule cells
Cerebellar cortex receives all cerebellar afferents or efferents?
Afferents
. Cerebellar cortex then regulates neurons in deep cerebellar nuclei
Medullary layer of cerebellum
. Underlying white white
. Contains both cerebellar cortex afferent and efferent fibers
. Comprises the central core of each folium
Climbing fibers
. Axons of neurons in contralat. Inf. Olivary nucleus in medulla enter cerebellum through inf. Cerebellar peduncle
. Project to and terminate on purkinje cell dendrites
. Fibers climb up the dendrite
. Carry training info related to movements
Mossy fibers
. All other cerebellar afferents fall into this category
. Numerous sites of origin, enter cerebellum through inf., middle., and sup. Cerebellar peduncles
. Project to and terminate on granule cells
. Carry state info about mm., internal and external environments
Cerebellar cortex efferents
. Purkinje neurons (to deep cerebellar nuclei)
. Deep cerebellar nuclei: axons exit cerebellum via sup. Cerebellar peduncle to terminate in contralat. Red nucleus and VL of thalamus
. Some axons exit via juxtarestiform body to terminate in ipsilateral vestibular nuclei and RF in brainstem
. Deep cerebellar nuclei in white matter (fastigial, globose, emboliform, dentate)
T/F connectivity of the cerebellar cortex is extremely uniform and very complex
T
Vestibulocerebellum
. Primarily of flocculonodular lobe and fastigial nucleus
. Inputs from ipsilateral vestibular ganglion and nuclei
. Projects mainly to ipsilateral vestibular nuclei (mostly lat. vestibular nucleus) directly or indirectly via fastigial nucleus through fibers in juxtarestiform body
. Allows modulation of vestibular functions in equilibrium and coordinated eye movements
. Control of axial mm. And vestibular reflexes by activation of vestibulospinal tracts and eye movements through connections w/ PPRF
Spinocerebellum
. Vermis, paravermal areas and fastigial, globose, and emboliform nuclei
. Subdivisions: vernal and paravermal
. Receives info from ipsilateral spinal cord, ipsilateral trigeminal system, and contralateral PMC
. Allows for mid-course corrections or adjustments ongoing and evolving movements
Inputs to spinocerebellum from ipsilateral spinal cord
. Spinocerebellar tracts
. Info on unconscious proprioception
Inputs to spinocerebellum from ipsilateral trigeminal system
. Mesencephalic nucleus of trigeminal
. Info on unconscious proprioception
Inputs to spinocerebellum from contralateral primary motor cortex
. projects ipsilateral pontine nuclei in basilar pons via corticopontine projections
. Pontine nuclei project to contralateral cerebellar cortex via pontocerebellar projections in middle cerebellar peduncle
. Copy of planned motor program sent to cerebellum
. Cerebellum knows position of body parts in space muscle tone, and what movements are planned
Vermal portion of spinocerebellum
. Vermis and fastigial nucleus
. Receives proprioceptive info primarily concerned w/ axial musculature via spinocerebellar tracts (DSCT, VSCT)
. Vermis projects to fastigial nucleus that then projects to ipsilateral vestibular nuclei and reticular formation and contralat. VL of thalamic nucleus
. Trunk area of VL will then project to trunk area of PMC
. Regulates accuracy of trunk, leg, head, and eye movement (posture, locomotion, gaze)
Connections in vermal portion of spinocerebellum allow for control of _____
. Axial musculature through both med. descending motor system pathways (vestibulo) and reticulospinal tracts (RST) and corticospinal tract (CST) of lat. descending motor system during execution of a movement
Paravermal region of cerebellum
. Paravermal cortex and globose and emboliform nuclei
. Receives proprioceptive info concerned w/ prox. Limbs via spinocerebellar tracts (DCST, VSCT)
. Projects to globose and emboliform nuclei that then go to contralat. VL in thalamus and to contralat. Red nucleus
. Limb area of VL projects to limb area of motor cortex
. Allows for control of lat. descending motor pathways (CST and RST) during movement execution
. Regulates accuracy of voluntary movements (reaching and grasping)
Cerebrocerebellum/pontocerebellum
. Lat. parts of cerebellar hemispheres and dentate nucleus
. Receives inputs from cerebral cortex (Premotor and M-1) and climbing fibers from contralateral inf. Olive
. Lat. hemisphere of cerebellum projects to dentate nucleus and then projects to VL of thalamus
. VL projects to PMC and M-1
Inputs to cerebrocerebellum from cerebral cortex
. Premotor and M-1 cortices project to ipsilateral pontine nuclei in basilar pons via corticopontine projections
. Majority of fibers descend through cerebral peduncles are corticopontine fibers
. Pontine nuclei project to contralat. Cerebellar cortex via pontocerebellar projections in middle cerebellar peduncle
. Allows cerebellum to be informed on motor planning
Input to cerebrocerebellum from contralateral inf. Olive
. Climbing fibers from contralat. Olive
. Inputs have been shown to play an important, but poorly understood role in motor learning
Functions of cerebrocerebellum
. Circuitry active w/ highly skilled movements of digits and complex motor tasks
. Lat. cerebellar hemispheres and dentate nucleus are highly active during these mental imaging or planning tasks
. Regulates higher aspects of behavior, functioning in planning of complex movements, regulating cognition and engaging in problem solving
