The Cerebellum

Question 1

Which are the only axons that leave the cerebellum cortex?

Answer 1

Axons of purkinje cells ▶️ project to deep cerebellar nuclei or vestibular nuclei at brain stem

• direct target of climbing fibers (from olivary nucleus - olivocerebellar tract)
• indirect target of mossy fibers (through granular cells)
• inhibited by basket and stellate cells

Question 2

Which is the only excitatory neuron of the cerebellar cortex?

Answer 2

granule cell ▶️ glutamate

Question 3

What fibers enter to the cerebellum as excitatory input carrying information from the other structures (spinal cord, inferior olivary nuclei, cerebral cortex, vestibular)?

Answer 3

• mossy fibers (tracts: vestibulo-, spino-, cortico(pontico)- cerebellar) ▶️ target: granule cells (indirect and diffuse input to purkinje cell)
• climbing fibers (olivocerebellar tract) ▶️ target: purkinje cells (direct, powerful, monosynaptic input to them)

Question 4

What produce lesion at anterior vermis? Sign

Answer 4

• degeneration from alcohol abuse

- gait ataxia

Question 5

What produce a posterior vermis lesion? Sign

Answer 5

• meduloblastoma or ependymoma

- truncal ataxia

Question 6

Clinical presentation hallmark of cerebellum lesions

Answer 6

• tremor in intended movements
• no paralysis or paresis
• ipsilaterally

Question 7

Difference of a lesion at hemisphere and in vermis

Answer 7

• hemisphere: distal musculature - intention tremor, dysmetria, dysdiadochokinesia, scanning dysarthria, gaze dysfunction, hypotonia
• vermal: difficulty to mantain posture (axial or trunk involvement), gait or balance. Romberg sign (-)