Cerebellum Flashcards
Cerebellum constitutes ____ of brain volume, but contains ____ of CNS cells
1/10 volume
>1/2 CNS cells
Most tracts bring information ____
Into cerebellum
Functions of cerebellum
Contribute to fine tuning of movement; involved in motor learning
(i.e., unconscious/subconscious proprioception)
Divisions of cerebellum
2 hemispheres & vermis
____ divides cerebellum into anterior & posterior lobes
Primary fissure
_____ separates the flocculonodular lobe
Dorsolateral fissure
The vermis is divided by the _____
Posterior border of tonsil
The ____ is in the superior vermis
Lingula
The ____ is in the inferior vermis
Nodule (Flocculonodular lobe)
Superior cerebellar peduncle connects to the ____
Midbrain
Middle cerebellar peduncle connects to the ____
Pons
Inferior cerebellar peduncle connects to the ____
Medulla
Name the deep cerebellar nuclei
Dentate
Emboliform
Globose
Fastigial
3 layers of cerebellar cortex
Molecular
Purkinjie
Granular
Molecular layer contains…
- Cell bodies of basket & stellate cells
- axons of granule cells that form parallel fibers
- dendrites of Purkinjie cells
Purkinjie layer contains…
Cell bodies of Purkinjie cells
Granular layer contains…
Cell bodies of granule & golgi cells
Mossy fibers originate from ____ and relay ____
Spinal cord & brainstem nuclei (eg. DSCT, VSCT)
Peripheral information
Mossy fibers excite ____ and ____, which in turn excite ____
Deep cerebellar nuclei and granule cells excite Purkinjie cells
Climbing fibers originate from ____ and relay ____
Inferior olivary nucleus
Sensory & visual information
Climbing fibers excite ____ and ____
Deep cerebellar nuclei and Purkinjie cells
What is the only output of the cerebellar cortex?
Purkinjie fibers
Purkinjie fibers function
Inhibit deep cerebellar nuclei that project out of cerebellum & other nuclei outside of cerebellum
Deep cerebellar nuclei receive ____ impulses from mossy & climbing fibers
Excitatory
Deep cerebellar nuclei receive ____ impulses from Purkinjie fibers
Inhibitory
Name the functional divisions of cerebellum
Flocculonodular lobe
Medial cerebellar hemispheres
Lateral cerebellar hemispheres
Flocculonodular lobe projects to the ____ nuclei and functions in…
Vestibular nuclei
Balance & eye movement
The vermis is part of the ____, and effects….
Flocculonudular lobe
Trunk & head & neck muscles
Afferents of Flocculonudular lobe
- vestibular fibers (info on head motion & position re gravity)
- superior colliculus & occipital lobe fibers (visual/visual reflex info)
- vermis receives visual, auditory, vestibular info and sensory from spinal cord
Efferents of Flocculonudular lobe
- projects to vestibular nuclei (control eye movements & head/eye coordination)
- fastigal nucleus projects to medial descending system (controls proximal muscles of body & limbs)
Lesion of Flocculonudular lobe
- truncal ataxia & in-coordination (impaired vestibular cues)
- failure of tandem gait test and Romberg’s test (may be unsteady/fall with eyes open/closed)
Function of Medial portions of cerebellar hemispheres (tonsils, globose nuclei, emboliform nuclei)
Posture & locomotion
Afferents of Medial cerebellar hemispheres
Receive sensory info from limbs
Efferents of medial cerebellar hemispheres
Globose & emboliform nuclei project to lateral descending system (control distal limb muscles)
Lesion of medial cerebellar hemispheres
- hypotonia
- pendular reflexes (keeps going)
- scanning speech
- appendicular ataxia (uncoordinated extremities) exhibited by dysmetria (fail finger to nose test)
- ataxic joint motion
- Intention tremor (disappears at rest)
Function of Lateral cerebellar hemisphere (with dentate nuclei)
- Planning complex actions
- conscious assessment of movement
- perceptual cognitive functions
Afferents of lateral cerebellar hemispheres
Receive info from cortex via pontine nuclei
(Frontopontine & temporopontine fibers -> pontine nuclei -> MCP)
Efferents of lateral cerebellar hemispheres
- Dentate nucleus fibers exit via superior cerebellar peduncle
- synapse with red nucleus
- projects to inferior olivary nucleus
- to thalamus -> premotor cortex
Fibers from the red nucleus to the thalamus form the ____
Dentatorubrothalamic tract
fibers of the dentatorubrothalamic tract join the ____ and function to…
Basal ganglia
Control & preparation of movement
Lesion of dentate nucleus
- decomposition of movements
- have to think about subconscious movements
- truncal ataxia evidenced by dysrhythmia and dysdiadochokinesia (inability to do rapid, alternating movements)
