Cerebellum Flashcards
What are some functions of the cerebellum?
- Smooth & coordinate ongoing movements
- Motor planning
- Motor Learning
What is the clinical significance of cerebellar tonsils?
- Mass lesion resulting in increased intracranial pressure
- Tonsils herniate through foramen magnum
- Compress medulla
What is another name for cortical gray matter?
Arbor vitae (tree of life)
Where is input into the cerebellum most from?
- Inferior cerebellar peduncle (restiform body)
- Middle cerebellar peduncle
Where is output from the cerebellum come from?
- Superior cerebellar peduncle
(Decussates in midbrain at level of inferior colliculus)
Cortex control movement on (BLANK) side of body
contralateral
Cerebellum coordinated & plans movements on the (BLANK) side of the body
ipsilateral
What is the function of the lateral hemisphere?
Motor planning for extremities
What is the function of the intermediate hemisphere?
Distal limb coordination
What does the lateral hemisphere influence?
Lateral Corticospinal Tract
What tracts does the intermediate hemisphere influence?
- Lateral cortical spinal tract
- Rubrospinal tract
What is the function of the vermis?
Proximal & trunk muscle control
What does the vermis influence?
Medial motor system
What is the function of the flocculonodular lobe?
Balance & vestibulo-ocular control
What does the flocculondular lobe influence?
Medial Longitudinal Fasciculus
What are the 4 deep cerebellar nuclei?
Dentate nucleus
Emboliform nucleus
Globose nucleus
Fastigial nucleus
Input into the Dentate nucleus is from?
Lateral cerebellar hemispheres
When is the dentate nucleus active?
Just before voluntary movement
Which two deep cerebellar nuclei make up the interposed nucleus?
Emboliform & Globose
Where does the interposed nucleus input from?
Intermediate part of cerebellar hemisphere
When is the interposed nuclei active?
During & in relation to movement
Where does the fastigial nucleus receive input from?
Vermis & some small from flocculonodular lobe
What are the 3 layers of cerebellar cortex?
- Granule cell layer
- Purkinje Cell layer
- Molecular cell layer
What is located in the granule cell layer?
- Small granule cells
- Glomeruli
What is located in the Purkinje cell layer?
Cell bodies of large, flask shaped purkinje cells
What is located in the molecular layer?
- Unmyelinated granule cell axons
- Purkinje cell dendrites
- Interneurons
Are mossy and climbing fibers excitatory or inhibitory?
Excitatory
Input to cerebellar cortex is through?
Mossy & climbing fibers
Output from cerebellar cortex to deep cerebellar nuclei is through? and are they excitatory or inhibitory?
Purkinje cells
- Inhibitory
Mossy fibers arise from (BLANK) and synapse on (BLANK)
- Numerous regions
- Granule cells
Climbing fibers arise from (BLANK)
Neurons in contralateral inferior olivary nucleus
How are parallel fibers formed?
Granule cells send axons to molecular layer which bifurcates
Parallel fibers run (BLANK) to Purknije fibers and have numerous (BLANK) contacts with multiple Purkinje fibers
- Perpendicular
- Excitatory
Purkinje cells carry all output from the (BLANK) into (BLANK)
- Cerebellar cortex
- Cerebellar white matter
Purkinje cells have (BLANK) synapses onto deep cerebellar & vestibular nuclei
Inhibitory
Which cerebellar cortex layers do basket & stellate cells have cell bodies?
Molecular layer
Basket and Stellate cells are excited by?
Parallel fibers of granule cells
Basket and Stellate cells cause lateral inhabitation of what?
Purkinje cells
(Stellate cells terminate on Purkinje dendrites & Basket cells terminate on Purkinje cell bodies)
Which cerebellar cortex layer has the cells bodies of Golgi cells?
Granule cells layers
Golgi cells are excited by?
Parallel fiber of granule cells
Golgi cells get feedback inhibition to what?
granule cells
What is the cerebellar glomerulus?
Special region of complex synaptic interaction within the granule cell layer
Describe the pathway of Dorsal spinocerebellar tract?
LE proprioceptors –> nucleus dorsalis of Clarke –> ipsilateral inferior cerebellar peduncle
Describe the input pathway Cuneocerebellar?
UE proprioceptors –> external cuneate nucleus (medulla) –> ipsilateral inferior cerebellar peduncle
Describe the input pathway of Ventral spinocerebellar tract?
LE interneurons –> cross in ventral white commissure –> cross with superior cerebellar peduncle
Describe the input pathway of Rostral spinocerebellar tract?
UE interneurons –> both superior cerebellar peduncle & inferior cerebellar peduncle
Oliviocerebellar fibers arise from? then cross?
- Arise from inferior olivary nucleus
- Cross in medulla to enter the contralateral cerebellum via inferior cerebellar peduncle
Input to the inferior olive is from?
- Red nucleus
- Cortex
- Brainstem nuclei
- Spinal cord
In regards to Vestibular input from both primary & secondary vestibular neurons project to cerebellum entering via?
Juxtarestiform body (along side inferior cerebellar peduncle)
What part of the cerebellum does visual input project to?
Ipsilateral cerebellar vermis & flocculonodular lobe
Where is visual & auditory inputs relayed from?
Brainstem nuclei
What is the role of the cerebellum in motor learning?
Climbing fiber input to cerebellar cortex has conditioning effect on activity of Purkinje cells:
(adjust flow through Purkinje cells
(Induces plastic changes in synaptic activity of Purkinje cells)
What is the role of Inferior olive in motor learning?
Integrates information from cerebral cortex, sensory system & cerebellar nuclei
What is the vascular territories of the cerebellum from the SCA?
- Superior 1/2 cerebellum
- Deep cerebellar nuclei
- Superior vermis
- Superior cerebellar peduncle
- Upper lateral pons
What is the vascular territories of the cerebellum from PICA?
- Inferior 1/2 cerebellum
- Inferior vermis
- Lateral medulla
What is the vascular territories of the cerebellum from AICA?
- Anterior strip of cerebellum
- Flocculus
- Middle cerebellar peduncle
- Inferior lateral pons
What is truncal ataxia and where would a lesion be to have caused this?
- Wide based, unsteady, drunk like gait, may have decreased sitting balance
- Associated with lesion to vermis
What is appendicular ataxia and where would a lesion be to have caused this?
- impaired coordination of limb movement
- Associated with lesions to intermediate & lateral cerebellar hemisphere
What is dysrhythmia?
Abnormal rhythm & timing
What is Dysmetria?
Abnormal undershoot or overshoot of target
What is Dysdiadochokinesia?
Difficult with rapid alternating movements
What is Postural tremor?
Oscillation when actively holding a position
What is intention tremor?
Oscillation when moving space toward a target
What is rebound?
impaired ability to check when sudden release of resistance
What is nystagmus?
Pupils beat unintentionally, may occur in direction or gaze or be upward beating
What is saccades?
Overshoot & undershoot target with eyes
What is smooth pursuit?
Jerky “saccadic” eye movement when following a target
Cerebellar dysfunction speech is?
Irregular fluctuations in volume & rate
What is hypotonia?
mild decrease in tone or reflexes
Cerebellar lesion produce symptoms (BLANK) to lesion
ipsilateral
