Cerebellum Flashcards
functions of the cerebellum
- coordinate movements
- maintain posture
- motor learning - procedural memory
molecular layer of cerebellum
- lies next to pial surface and has few neurons
- cell bodies of basket cells and stellate cells
purkinje layer of cerebellum
-purkinje cell bodies
granular layer of cerebellum
- deepest
- granule cells and a few golgi cells
white matter of cerebellum
axons of neurons
purkinje cells
- output cells from cerebellar cortex
- inhibit the cerebellar nuclei and the vestibular nuclei
- GABA
- highly differentiated with many dendrites
granule cells
- smallest neurons
- only excitatory neurons
- Glutamate
stellate cells
- axons synapse only with purkinje cells and inhibit them
- star shaped dendrites
golgi cells
- inhibitory
- GABA
- largest scattered neurons with short axons
basket cells
- axons synapse with purkinje cells and inhibit them
- GABA
afferent fibers
- climbing fibers
- mossy fibers
climbing fibers
- from inferior olive
- myelinated with excitatory influence on purkinje cells
- convey info regarding movement errors to the cerebellum
mossy fibers
- from spinal cord, reticular formation, vestibular system, and pontine nuclei
- synapse with granulocytes
- convey somatosensory and cerebral cortex motor info to cerebellum
vestibulocerebellum (archicerebellum)
- functional name for flocculonodular lobe
- input: vestibular apparatus and visual areas
- output: vestibular nuclei
- function: infleunce eye movements and postural muscles of head and body
What are the functional divisions of the cerebellum?
- vestibulocerebellum/archicerebellum: eye movement and neck/trunk movement
- spinocerebellum/paleocerebellum: axial and LE movements, gait and station
- pontocerebellum/neocerebellum: precise, coordinated movments of extremities, mainly UE
spinocerebellum (paleocerebellum)
- functional name for vermis and paravermal region
- input: somatosensory info, visual, auditory, and vestibular info
- output: medial UMN, lateral UMN
- function: control ongoing movement via brainstem descending tracts
pontocerebellum (neocerebellum)
- input: cerebral cortex (premotor, sensorimotor, and others) via pontine nuclei
- output: motor and premotor cortex
- function: coordination of voluntary movements, planning of movements, and timing
What nuclei does the vestibulocerebellum send to?
- fastigial nucleus
- vestibular nucleus
What nuclei does the spinocerebellum send to?
- dentate nucleus
- globose and emboliform nuclei
- fastigial nucleus
What nuclei does the cerebrocerebellum send to?
- dentate nucleus
- globose and emboliform nuclei
What afferent fiber pathways enter the cerebellum through the vestibular system?
- vestibular nuclei
- CN VIII
What afferent fiber pathways enter the cerebellum through the spinal cord?
- anterior spinocerebellar tract
- posterior spinocerebellar tract
- cuneocerebellar tract
What afferent fiber pathways enter the cerebellum through the cerebral cortex?
- cortico-pontocerebellar
- cortico-olivocerebellar
- cortico-reticulocerebellar
What fiber pathways relay unconscious proprioception about limb movement?
- posterior spinocerebellar tract
- cuneocerebellar tract
posterior spinocerebellar tract
- axons carrying unconscious proprioception from lower limb
- 1st order neuron enters via DRG and ascends in gracile fasciculus
- synapse in nucleus dorsalis of Clark (gray matter C8-L2)
- 2nd order neuron ascends in dorsolateral funiculus (posterior spinocerebellar tract)
- enters cerebellum via the inferior cerebellar peduncle
cuneocerebellar tract
- axons carrying unconscious proprioception from upper limb
- 1st order neuron enters DRG and ascends cuneate fasciculus
- synapses in accessory (external/lateral) cuneate nucleus (lower medulla)
- 2nd order neuron from accessory cuneate nucleus ascends to cerebellum and enters via the inferior cerebellar nucleus
cerebellar peduncles
- afferent fibers enter crebellum and efferent fibers leave the cerebellum
- superior, middle, and inferior
superior cerebellar peduncle
- major Efferent route from the globose, emboliform, and dentate nuclei
- Afferent fibers from ventral (anterior) spinocerebellar tract run here too
middle cerebellar peduncle
- largest peduncle
- afferent fibers from pontine nuclei relayed to cortex
inferior cerebellar peduncle
-primarily afferent pathways from spinal cord
deep nuclei
- fastigial
- globose
- emoliform
- dentate
Where does the fastigial nucleus send to?
- vestibular nuclei
- pontine reticular formation and medullary reticular formation
Where does dentate nucleus send to?
red nucleus and thalamus
Where does the globose adn emboliform nuclei send to?
red nucleus and thalamus
What side do unilateral cerebellar lesions affect?
ipsilateral
ataxia
- common to all lesions of cerebellum
- voluntary, normal strength, jerky, and inaccurate movements not associated with hyperstiffness
lesions of the vestibulocerebellum
- connections between the vestibular system and the flocculonodular lobe
- nystagmus
- truncal ataxia: difficulty maintaining sitting and standing balance
- truncal instability (titubation)
- can’t tandem walk
lesions of spinocerebellum
- connections between the cutaneous and proprioceptive information coming from the spinal cord to the vermis and paravermis regions
- gait and truncal ataxia: wide base staggering base
midline ataxia
-ataxic syndromes caused by vestibulocerebellar and spinocerebellar disease
truncal instability
-titubation
-gait ataxia
equilibratory (gait) ataxias
-gait ataxia
titubation
tremor of the trunk in an anterior-posterior plane at 3-4 Hz
gait ataxia
wide based, irregular steps with lateral veering
lesions of the cerebrocerebellum
- dysarthria
- ataxic gait: fall toward lesion
- decomposition of movements
- dysdiadochokinesia
- dysmentria
- action tremor
dysdiadochokinesia
inability to rapidly alternate movements
dysmetria
inability to accurately move an intended distance
action tremor
shaking of the limb during voluntary movement
appendicular ataxia
- dysfunction of the cerebellar hemispheres results in ataxia of the extremities
- ataxia of speech (scanning dysarthria)
- hypotonia
- decomposition of movement
- dysmetria
- dysdiadochokinesia
cerebellar ataxia
- romberg +
- unable to stand with feet together (with or without eyes open)
- normal vibratory sense, proprioception and ankle reflexes
sensory ataxia
- can stand with feet together with eyes open, but not with eyes closed
- romberg +
- abnormal vibratory sense, proprioception and ankle reflexes
exam of vestibulocerebellum and spinocerebellum
- station
- walking
- tandem gait
exam of cerebrocerebellum
- rapid alternating movements
- finger-to-nose
- toe-to-finger
- heel-to-shin
- rebound and ceck reflex
- speech
