Cerebellum Flashcards
Where does the anterior lobe receive input from and what is its role?
Input from the spinocerebellar tracts
Regulation of muscle tone
Where does the posterior lobe receive input from and what is its role?
Corticopontocerebellar tracts
Coordination of voluntary motor activity
Where does the flocculonodular lobe receive input from and what is its role?
Input from the vestibular system
Posture and balance
What are some characteristics of the superior cerebellar peduncle?
Major output from cerebellum
Efferents from all three deep cerebellar nuclei tot he regulated the rubrospinal and corticospinal UMN systems
Only peduncle to decussate
What is the middle cerebellar peduncle?
Largest cerebellar peduncle and connects to the pons
Carries afferent pontocerebellar fibers to the neocerebellum
What is the inferior cerebellar peduncle?
Consists of two divisions - restiform and juxtarestiform bodies
Involved in the reticular and vestibular systems
What are the three major cellular layers of the cerebellum?
Granule cell layer - small and tightly packed layer of excitatory interneurons
Purkinje cell layer - purkinje cell bodies
Molecular cell layer - majority of synapses are made here
What are the two cerebellar inputs?
Mossy Fibers - excitatory neurons that ascend through the white matter and synapse onto granule cell dendrites
Climbing fibers - Project from the contralateral inferior olivary nucleus, excitatory, dampen purkinje response to input from parallel fibers
What cell is the output from the cerebellum?
Purkinje cells
What are basket cells and stellate cells?
Inhibitory neurons that reside in the mollecular layer and synapse onto purkinje cells
Receive input from parallel fibers and promote lateral inhibition of adjacent purkinje cells
What are golgi cells?
Reside in the granule cell layer, but project dendrites to the molecular layer to synapse with parallel fibers
Golgi cells then synapse on granule cells, providing a system of feedback inhibition to granule cells
What are the dentate nuclei?
Largest deep cerebellar nuclei, in lateral hemisphere
Projects to the red nucleus, VL, and inferior olivary nucleus
Involved in initiation, planning, timing of volitional movement
What are the Emboliform and Globose nuclei?
Interposed nuclei, within intermediate hemisphere
Outputs relayed via the VL to the corticospinal tract regulating distal muscles
Outputs to the red nucleus to give rise to the crossed rubrospinal tract
What are the fastigial nuclei?
Input from vermis and flocculonodular lobe
Output to VL, tectum, and superior cerebellar peduncle
Involved in muscle tone and posture via vestibulospinal tract
What are the vestibular nuclei?
NOT deep nuclei
Output to medial longitudinal fasciculus and juxarestiform body
Describe corticopontine input to the cerebellum
Pontocerebellar fibers enter the middle cerebellar peduncle and relay information via mossy fiber projections to the entire cerebellum, except the nodulus
Describe spinocerebellar input
Dorsal - lower extremity, trunk. Inferior peduncle mossy fibers
Cuneo - upper extremity, trunk. inferior peduncle, mossy fibers
Ventral - coordination of posture and lower limb movement, superior peduncle, double crossed
Describe inferior olivary nuclear complex input
Olivocerebellar fibers decussate before entering the inferior cerebellar peduncle
Information conveyed via climbing fibers to reach the contralateral cerebellum
Describe the function of the lateral cerebellar hemisphere
Projects to dentate nucleus, then to contralateral VL of thalamus
Then projects to lateral CS tract and parvocellular red nucleus
Describe the function of the intermediate/paramedian hemisphere
Project to the emboliform and globose nuclei then to contralateral VL and red nucleus
Continue to lateral CS tract and rubrospinal tract
Describe the function of the vermal/median zone
Projects to the fastigial nucleus, then to the VL
From there, to the anterior CS tract
Also project to the uncinate fasciculus to the vestibular nuclei
Describe the function of the flocculonodular lobe/vestibulocerebellum
Vestibvular nuclei/ganglia project to the ipsilateral flocculonodular lobe
Direct reciprocal connections are unique in the cerebellum
Out put to the medial longitudinal fasciculus provides ocular control
What vasculature provides blood supply to the cerebellum?
Posterior inferior cerebellar artery
Anterior inferior cerebellar artery
Superior cerebellar artery
What are the symptoms of a cerebellar hemisphere lesion?
Ataxia towards lesion
Hypotonia, dysmetria, intention tremor, dysdiadochokinesis
Ipsilateral to lesion
What are the symptoms of a vermis lesion?
Affects Medial motor system
Truncal ataxia
Dysarthria, ocular ataxia and nystagmus
What can cause false localization of ataxia?
Lesions in the peduncles or pons can produce ataxia without direct cerebellar involvement
What is Friedreich’s ataxia?
Autosomal recessive neurodegenerative disorder that targets dorsal and lateral columns, can involve cerebellar peduncles
Ataxia, areflexia, impaired dorsal/medial lemniscal symptoms, progressive weakness with babinski
What is Wernicke’s encephalopathy?
Irreversible neuronal degeneration (Wernicke-Korsakoff syndrome)
Caused by B1 deficiency/alcoholism
Symptom triad: Cognitive dysfunction, gait ataxia, and nystagmus
