Cerebellum and Reticular Formation

Question 1

Generally, the cerebellum has connections with the

Answer 1

Vestibular system, spinal cord, cerebral cortex, and pons of the brainstem

Question 2

Connections are arranged so that each cerebellar hemisphere is primarily concerned with the coordination of movements on the (contralateral/ipsilateral) side of the body

Answer 2

Ipsilateral. Outputs from the cerebellum stay on the same side whereas outputs from the cortex cross in the brainstem contra-laterally.

Question 3

How is the cerebellum part of the motor system?

Answer 3

It is responsible for unconscious coordination and fine control of muscle actions. Ex: holding a pencil for a long time.

Question 4

3 lobes of the cerebellum

Answer 4

Anterior, posterior/middle, and flocculonodular

Question 5

2 fissures of the cerebellum and what do they separate?

Answer 5

1. The Primary fissure separates the anterior from the posterior/middle
2. The posterolateral fissure separates the posterior/middle from the flocculonodular

Question 6

The right and left hemispheres of the cerebellum are joined by the

Answer 6

Vermis

Question 7

What afferent origin is in the flocculonodular lobe and what is it’s efferent function?

Answer 7

The vestibulo-cerebellum is in the flocculonodular lobe.

Efferent function is responsible for maintaining posture and balance. Also plays a role in the VOR.

Question 8

Where is the spino-cerebellum afferent origin located at in in the cerebellum and what is its efferent function?

Answer 8

It is located in a middle line down the center of the cerebellum containing the anterior lobe, posterior lobe, and some of the vermis.

Efferent function is to regulate muscle tone.

Question 9

The lateral portions of the cerebellum contain which afferent origin and what is its efferent function?

Answer 9

The lateral portion of the cerebellum contains the pontocerebellum.

Efferent function is skilled movements (integration of various muscle groups)

Fibers come to the pons from the cerebral cortex. Synapse. Fibers cross over to the other side of the pons and insert into the lateral cerebeullum.

Question 10

Where is the white and grey matter located at in the cerebellum

Answer 10

The white matter is in the center

The grey matter is in the periphery cortex and contains the molecular, purkinje, and granular layers

Question 11

Which layers are in the cerebral cortex of the cerebellum (grey matter)

Answer 11

Outer
Molecular
Purkinje 
Granular
Inner

Question 12

Two main type of cells that deliver input to the cerebellum (afferent input)

Answer 12

Both are excitatory

1. Climbing fibers
2. Mossy fibers

usually via the inferior and middle cerebral peduncles (makes sense bc the superior peduncle is efferent only, the middle peduncle is mostly afferent and the inferior peduncle is 50/50)

Question 13

Where do climbing fibers originate

Answer 13

Below the cerebellum (in the medulla in the olivary complex)
Synapse onto dendrites and somas of purkinje cells which are in the molecular layer of the cerebral cortex.
Also synapse directly with the cerebellar nuclei

Question 14

The climbing fibers synapse with what 3

Answer 14

1. Synapse directly with the cerebellar nuclei
2. Synapses onto cell bodies of purkinje cells
3. Synapses onto dendrites of purkinje cells

Question 15

Where do mossy fibers originate

Answer 15

They originate in the vestibular and pontine nuclei majorly and minorly from the spinal cord

Question 16

The mossy fibers synapse with what 4

Answer 16

1. Synapse with granular cells called cerebellar glomeruli in the granular layer.
2. Can directly synapse with the cerebellar nuclei
3. Can synapse with the purkinje cells
4. Some branches excite local inhibitory neurons in the molecular layer such as stellate cells or basket cells

Question 17

Inhibitory neurons in the molecular layer

Answer 17

Stellate and basket cells

Question 18

Inhibitory cells in the granular layer

Answer 18

Golgi

Question 19

Cells in the purkinje layer and are they excitatory or inhibitory?

Answer 19

Only purkinje soma are in the purkinje layer and they are inhibitory

The purkinje cell dendrites travel to the molecular layer. Their axons project through inner granular layer and into the white matter. They synapse with the cerebellar nuclei deep in the white matter

Question 20

Where are granular cells located at and are they excitatory or inhibitory?

Answer 20

They are excitatory.
Soma is in granular layer
Axons are in molecular layer

Question 21

Cells found in the granular layer (inner cortex)

Answer 21

Soma of granular cells- excitatory

Golgi cells- inhibitory interneurons

Question 22

The purkinje cell body, dendrites, and axons are located where?

Answer 22

The purkinje cell dendrites travel to the molecular layer. Their axons project through inner granular layer and into the white matter. They synapse with the cerebellar nuclei deep in the white matter

Question 23

What cells are found in the molecular layer (outer cortex)

Answer 23

Contains inhibitory basket and stellate cells.
Also contains dendritic tree of purkinje cells
Two branched processes of granular cell axons

Question 24

Cerebellar CORTEX output

Answer 24

All output is through the purkinje cell axons via the cerebellar nuclei.

Most outputs exit the cerebellum via the superior cerebral peduncle. Others pass through the red nucleus, vestibular nuclei, and reticular formation.

Question 25

Cerebellum is about ___% of the brain’s mass, but contains up to ___% of the brains neurons.

Answer 25

10% of the brains mass
Contains 50% of the brains neurons

Few cell types are arranged in a receptive, highly order array.

Question 26

The peduncles (superior, middle, or inferior) of the cerebellum contain which tracts? efferent, afferent, or both?

Answer 26

Superior- Mostly efferent. From the cerebellar nuclei.

Middle- 99% afferent to the cerebellum. This is the ponto-cerebellar pathway. Signal originates in the basal pontine nuclei and sends fibers to the lateral regions of the anterior and posterior/middle lobes of the cerebellum. Can also travel contralaterally and terminate as mossy fibers.

Inferior- both 50/50

Question 27

Middle cerebellar peduncle is a major ___ tract and originates and terminates where

Answer 27

The middle peduncle is a major SENSORY tract (99% afferent).

The fibers originate in the basal pontine nuclei and travel to the lateral regions of the posterior/middle and anterior lobes. (Aka peripheral, pontocerebellar pathway)

Question 28

The cerebellum is connected to the posterior brainstem by the ____

Answer 28

Superior, middle, and inferior cerebellar peduncles

Question 29

Granular cells send their axons to the ____ layer, where they split into horizontally running parallel processes. These form an ____ synapse with the dendritic tree of the ___ cells.

Answer 29

Send their axons to the molecular layer.

They form an excitatory synapse with the dendritic tree of the purkinje cells.

Question 30

Efferent output from the cerebellar cortex is entirely via the axons of the ___ cells

Answer 30

Purkinje

Question 31

Purkinje dendrites have ___, which interact with the parallel processes of ____ cells. Approx 200,000 time per purkinje cells.

Answer 31

spines

granular

Question 32

The reticular formation is important in which 3 functions

Answer 32

1. Autonomic functions
2. Reflex functions
3. Limbic functions

Question 33

3 divisions of the reticular formation

Answer 33

1. Median (midline)
2. Para-medial (On either side of midline). Mainly efferent.
3. Lateral (on either side of the para-medial. Mainly afferent.

RF interacts with everything.

Question 34

5 main functions of the reticular formation

Answer 34

1. Rhythmic movements/patterns. Including eye movements, chewing, swallowing, vomitting, walking, GI tract movement
2. Cardiovascular control
3. Respiratory control
4. Sleeping and wakefulness. Involved with REM and non-REM
5. Sensory modulation. Gate control. Controls perception of stimulus.

Question 35

What NS does the reticular formation mostly act upon

Answer 35

The autonomic