Lab 8.2: Cerebellar Pathways

Front 1

What are the first order neurons of the DSCT? Where do they synapse with second order neurons?

Back 1

*primary afferents from the limbs, usually 1-A neurons
*synapse with second order neurons in Clarke's nucleus in the gray matter of the spinal cord between L2 and C8

Front 2

Where is Clarke's nucleus located? What neurons synapse here?

Back 2

In the gray matter of the spinal cord between L2 and C8. First order neurons of the DSCT synpase with second order neurons of the same tract.

Front 3

Where in the spinal cord does the DSCT run?

Back 3

On the lateral margins, ventral to the dorsal horns.

Front 4

How do do second order neurons of the DSCT enter the cerebellum? Where do these neurons synapse?

Back 4

They enter through the ICP and synapse on Purkinje cells in the spinocerebellar cortex; there are some direct synapses on the interposed nuclei.

Front 5

Which deep nuclei of the cerebellum are a part of the DSCT? How do fibers leaving these nuclei leave the cerebellum and where do they go?

Back 5

*interposed
*fibers leave through the SCP and cross to synapse at the contralateral red nucleus and VL region of the thalamus

Front 6

What is the function of the cerebrocerebellar system?

Back 6

It receives a copy of the "motor plan" from the cerebrum and is involved in motor planning and practicing complex movements.

Front 7

Where is the cell body of the first order neuron of the cerebrocerebellar system? Where does this neuron travel? Where does it synapse?

Back 7

*cell body is in the cerebral cortex
*travels down ipsilateral corticopontine tracts
*synapses on ipsilateral pontine nuclei

Front 8

Describe the path of the second order neuron of the cerebrocerebellar system - where is its cell body, how does it travel, and where does it synapse?

Back 8

*cell body is in the pontine nucleus
*decussates and passes through the contralateral MCP
*synapses on Purkinje cells in the contralateral cerebrocerebellar cortex

Front 9

Which of the deep nuclei is involved in the cerebrocerebellar pathway? How do projections from this nucleus leave the cerebellum?

Back 9

*the dentate nucleus
*projections leave through the SCP

Front 10

Continue the path of the cerebrocerebellar tract after it leaves the cerebellum.

Back 10

Fibers decussate and synapse on either the contralateral red nucleus or VL region of the thalamus. From the thalamus, fibers travel to the primary motor cortex.

Front 11

Describe the basic loop (in general terms) of the cerebrocerebellar pathway.

Back 11

Information travels from the cerebral cortex to the cerebellum and back to the cortex.

Front 12

Describe the basic loop (in general terms) of the spinocerebellar tract.

Back 12

Information from the limbs travels to the cerebellum and is then passed to the contralateral cerebral cortex.

Front 13

What are the two routes taken by CN VIII fibers arising from the peripheral vestibular apparatus?

Back 13

1.Synapse at ipsilateral vestibular nucleus
2.Pass through the ICP and synapse on Purkinje cells in the FN lobe and vermis

Front 14

What is the path taken by nerves arising from the vestibular nucleus that enter the cerebellum?

Back 14

They pass through the ipsilateral ICP and synapse on Purkinje cells in the vermis and FN lobe.

Front 15

Where do projections from the Purkinje cells of the FN lobe travel?

Back 15

1.To synapses in the ipsilateral fastigial nucleus
2.Through the ipsilateral ICP to synapses on the vestibular nucleus

Front 16

What are the functions of the vestibulocerebellar pathways?

Back 16

*posture
*balance
*eye movements

Front 17

Where do projections from the fastigial nucleus travel?

Back 17

1.To the reticular formation
2.Through both ipsilateral and contralateral ICPs to synapse on vestibular nuclei on both sides

Front 18

Where do descending fibers of the reticular formation travel?

Back 18

Down the reticulospinal tract.

Front 19

Where do outgoing (i.e. not to cerebellum) fibers of the vestibular nuclei travel?

Back 19

*to the spine via the ventral and lateral vestibulospinal tracts
*rostrally via the MLF

Front 20

What is the function of the inferior olivary nucleus?

Back 20

Adaption of movement to changes in the environment.

Front 21

Describe the output tracts of the inferior olivary nuclei.

Back 21

Project climbing fibers through the contralateral ICP...
*to all three cerebellar cortices where they synapse on Purkinje cells in 1:1 ratio
*to direct synapses on the deep nuclei

Front 22

What 3 structures send inputs to the inferior olivary nuclei?

Back 22

Red nuclei, cerebral cortex, and spinal cord.

Front 23

Why are lesions to the MCP associated with gait ataxia?

Back 23

Because connections from the contralateral pons are lost.

Front 24

What is the effect of a lesion to the SCP?

Back 24

Intention tremor

Front 25

What effects will be seen with a lesion to the left pontine nucleus?

Back 25

Ataxia on the right (i.e. contralateral) side.

Front 26

Lesions to the ICP can cause:
1.ataxia
2.nystagmus
What structures are damaged to cause each of these effects?

Back 26

1.DSCT or fibers from the inferior olivary nucleus
2.Fibers to or from the vestibular nuclei

Front 27

Lesions to the cerebellum or associated structures almost always produce ipsilateral effects, but there are at least 2 exceptions - what are they?

Back 27

1.Unilateral lesions to pontine nuclei
2.Unilateral lesions to inferior olivary nucleus

Front 28

What is the blood supply for the ICP?

Back 28

PICA

Front 29

What is the blood supply for the MCP?

Back 29

AICA

Front 30

What is the blood supply for the SCP?

Back 30

Superior cerebellar artery.