Cerebellum Flashcards
Rhombic lip structures
Granule, basket, and stellate neurons
*Also gives rise to pontine nuclei and inferior olive
Cerebellar developmental origin
Comes from the two sources of the alar plate:
- Ventricular zone => cerebellar plate
- Mantle Layer => deep cerebellar nuclei, Purkinje cells, and Golgi cells
Flocculonodular Lobe
Oldest area of cerebellum phylogenetically that receives input from vestibular nuclei and projects to same nuclei
Location of basket and stellate interneurons
Molecular layer of Cerebellar cortex
Output of Purkinje cells
Inhibitory; fibers run to deep nuclei
*Except for Purkinje cells in the Flocculonodular lobe
Location of Golgi and Granule interneurons
Granule Cell Layer; granule cells have axons that branch and form parallel fibers
Deep nuclei of Cerebellum
- Fastigial nucleus (efferents to vestibular/reticular nuclei)
- Globose nucleus (efferents to red nucleus; VA/VL
- Emboliform nucleus (efferents to red nucleus; VA/VL)
- Dentate nucleus (efferents to red nucleus; VA/VL)
* Can see these dorsally in the caudal pons
Interpositus Nuclei
Globose + Emboliform nuclei
Restiform Body
Inferior Cerebellar Peduncle
Connects to spinal cord and medulla; contains efferents from flocculonodular lobe
Brachium pontis
Contains a connection for pontine nuclei to project their axons to the CONTRALATERAL cerebellar cortex
Brachium conjuntivum
Major output peduncle; contains axons from…
- Interpositus nuclei
- Dentate nuclei
- Ventral spinocerebellar axons
Spinal cord projections to cerebellum
DRG cells representing C8-L2 synapse in Clarke’s column and ascend ipsilaterally as the dorsal spinocerebellar tract
=>enters Restiform body with proprioceptive info
*Ends up on same side as 1st order neuron
Lumbosacral projections to cerebellum
Axons cross from this region and form the ventral spinocerebellar tract
=>Enters the Superior Cerebellar peduncle
*Info ends up on same side as 1st order neurons
What’s the only afferent pathway in the Superior Cerebellar Peduncle?
Ventral Spinocerebellar Tract
Cuneocerebellar Pathway
Contains proprioceptive input from >C8 and synapses in the accessory cuneate nucleus
=>Axons ipsilaterally project thru Restiform body
“Climbing Fibers”
Axons from the inferior olive cells rising to travel in the restiform body
Mossy Fibers
All sources of input to the cerebellum excluding the climbing fibers
Source of inhibitory input to the cerebellum
Reticular formation nuclei
Ventral Zone of Cerebellum
(Medial Zone)
Involved in the coordination of ongoing movement; sends efferents to fastigial nucleus
Intermediate Zone of Cerebellum
(Paramedian Zone)
Involved in the coordination of ongoing movement; receives afferents from the spino/cuneocerebellar tracts
*Efferents project to interpositus nuclei
Spinocerebellum
Median and paramedian areas of cerebellum; main input is unconscious proprioceptive info
*Head, neck, trunk= median
Extremities= Paramedian
Lateral Zone
Involved in the planning and timing of movement; receives afferents via the ventral spinocerebellar tract
*Efferents project to dentate nucleus
Midline lesions of cerebellum
Truncal ataxia
Wide-stance
Cerebellar dysarthria
Ocular atxia
Hemisphere lesions of cerebellum
Ataxia
*Pt. will fall to side of lesion
Dysmetria
*Test w/ finger-nose test
Dysrhythmia
Tremor
*All signs/symptoms are ipsilateral
Medulloblastoma
Produces truncal ataxia and possible hydrocephalus
- Vomiting
- Most common brain tumor in children
Most common cancers to metastasize to the brain
- Breast
- Lung
- Skin
Friedrich’s Ataxia
AR disorder resulting from mutation of Chromosone 9; GAA repeat
=>degeneration of DRGs, Purkinje cells, peduncles, etc.
Signs: Ataxia Areflexia Impaired fine touch Progressive paralysis w/ Babinski *Scoliosis
*Most pts. typically die @ 25-30yrs
Frataxin
Protein encoded for mitochondrial fnxn
-Abnormal in Friedrich’s ataxia
Wernicke’s Encephalopathy
Thiamine deficiency resulting in acute symptoms
- Triad:
1. Cognitive dysfunction
2. Ataxia
3. Oculomotor abnormalities - Pt. will also show confabulation due to degeneration of MDS nuclei and hippocampus
- Treated w/ Thiamine
Paraneoplasia
Immune cells recruited to fight cancer turn on normal cells in cerebellum
Most common cancers to cause paraneoplasia
- Lung
- Breast
- Ovarian
Cerebellar Pathway
Cerebellum compares intended movement (via pontine nuclei) w/ actual movement (via proprioceptive info)
=>projects to VA/VL to modulate further movement
For the purposes of this test, if you see a child w/ cerebellar symptoms, what should you consider first?
Medulloblastoma
