13.0 Cerebellum

Question 1

What are the three afferent tracts for the spinocerebellum?

Answer 1

Posterior spinocerebellar tract.

Cuneocerebellar tract.

Anterior spinocerebellar tract.

Question 2

What is the general funciton of the cerebrocerebellum?

Answer 2

Planned movement – particularly of the upper extremity.

Question 3

Which of the cells of the cerebellum are primarily in charge of carrying efferent signals from the cerebellum?

Answer 3

Purkinje cells

Question 4

What is the general function of the spinocerebellum?

What is the more specific function of the paravermal region?

What is the more specific function of the vermis?

Answer 4

Facilitation of ongoing movements - especially gait and station.

The paravermal region facilitates the ongoing movements of limb muscles and facilitates gait and station.

The vermis facilitates the ongoing movements of the trunk.

Question 5

Which afferent pathway of the cerebellum synapses at the dorsal nucleus of Clark?

What information is carried in that tract?

Answer 5

The posterior spinocerebellar pathway.

Unconscious proprioception from the lower limb.

Question 6

Which of the cerebellar afferent pathways utilizes the juxtarestiform body?

Answer 6

The vestibulocerebellar tract (from the vestibular nuclei and CN VIII to the vestibulocerebellum).

Question 7

Where does the spinocerebellum send efferents?

Answer 7

Paravermal region: globose and embolliform nuclei

Vermis: fastigial nucleus

Question 8

From where does the spinocerebellum receive input?

Answer 8

Spinal interneurons

Sensorimotor cortex

Somatosensory areas (less so)

Visual / auditory / vestibular areas (less so)

Question 9

What cells are affected by climbing fibers?

Is this an excitatory or inhibitory interaction?

Answer 9

Purkinje cells are excited by climbing fibers.

Question 10

The spinal cord afferents to the spinocerebellum enter via which structure?

Answer 10

The restiform body of the inferior cerebellar peduncle – except for the anterior spinocerebellar tract, which uses the superior cerebellar peduncle.

Question 11

Where do the first oder fibers of the cuneocerebellar tract synapse?

Answer 11

In the accessory cuneate nucleus.

Question 12

What efferent tract of the cerebellum bypasses the deep nuclei of the cerebellum?

Which cerebellar peduncle does this tract travel through?

Answer 12

The tract from the vestibulocerebellum to the vestibular nuclei.

Passes through the inferior cerebellar peduncle.

Question 13

Which afferent tract of the cerebrocerebellar module uses “climbing fibers?”

Answer 13

The cortico-olivocerebellar system.

Question 14

What is the primary function of the vestibulocerebellum?

Answer 14

Eye movement and balance/equilibrium.

Has influence over the eye movements and the postural muscles of the head and body.

Question 15

Which of the cells of the cerebellum are excitatory?

What neurotransmitter do these cells use?

What neurotransmitter do the inhibitory cells use?

Answer 15

Just the granule cells are excitatory. They use glutamate.

All other cells of the cerebellum are inhibitory and use GABA.

Question 16

Where does the cerebrocerebellum send efferents?

Answer 16

Dentate nucleus.

Question 17

What afferent tract of the cerebellum utilizes the middle cerebellar peduncle?

Answer 17

The pontine nuclei (which receive afferents from the cerebral cortex) entering the cerebrocerebellum.

Question 18

Where does the vestibulocerebellum send efferents?

Answer 18

Both to the fastigial nucleus, and directly to the vestibular nucleus – bypassing the deep nuclei (this is through the inferior cerebellar peduncle).

Question 19

What are the three afferent tracts for the cerebrocerebellar tract?

Answer 19

Cortico-olivocerebellar

Cortico-reticulocerebellar

Cortico-pontocerebellar

Question 20

What sx do we see s/p a lesion to the cerebrocerebellum?

Answer 20

Intention tremor

Dysarthria

Dysdiadochokinesia

Dysmetria

Ataxic gait (tendency to fall towards the lesion)

Decomposition of movements (this is a big one, because it explains many of the above).

Question 21

Which cerebellar afferent tract decussates twice?

Answer 21

The anterior spinocerebellar tract.

Question 22

What are the three layers of grey matter in the cerebellum, and what cells are found in each layer?

Answer 22

Molecular layer

• Basket cells / Stellate cells

Purkinje layer

• Purkinje cells

Granular layer

• Granule cells
• Golgi cells

(White matter)

Question 23

How do we differentiate between sensory and cerebellar ataxia?

Answer 23

This is determined by the results of Romberg’s sign. Patients with cerebellar ataxia are unlikely to be able to stand without swaying even with their eyes open. Patients with sensory ataxia can stand with their eyes open, but sway or fall if they close their eyes. Furthermore, patients with sensory ataxia have abnormal vibratory sense, proprioception and ankle reflexes.

Question 24

What sx do we see s/p a lesion to the vestibulocerebellum?

Answer 24

Nystagmus

Truncal ataxia

Truncal instability

Inability to tandem walk

Question 25

What cerebellar afferent carries unconscious proprioception from the upper limb?

Answer 25

The cuneocerebellar pathway.

Question 26

What is the anatomical region of the vestibulocerebellar module?

Answer 26

The “flocculonodular lobe.”

Question 27

What sx do we see s/p a lesion to the spinocerebellum?

Answer 27

Gait and truncal ataxia

Wide base

Staggering base

Inability to tandem walk

(Similar to vestibulocerebellum, but no nystagmus and a wide base)

Question 28

What is midline ataxia?

What sx do we expect to see?

Answer 28

A group of syndromes associated with spinocerebellar or vestibulocerebellar disease.

Truncal instability and equilibratory (aka, gait) ataxia.

Titubation: shaking back and forth while sitting.

Question 29

What cells are affected by mossy fibers?

Is this an excitatory or inhibitory interaction?

Answer 29

Mossy fibers excite granulocytes of the cerebellum.