Cerebellum

Front 1

List the steps of the cerebellar loop:

Back 1

Sensory/motor cortex--> pons--> cerebellum--> VLc--> M1 cortex

Front 2

What "loops" does the corticospinal/corticobulbar tract get influence from?

Back 2

Both cerebellar and b.g. loops, via the VL nuclei of the thalamus.

Front 3

Cerebellar disease or damage results in a decrease in the ____ of movement without producing paralysis, rigidity or frank dyskinesias like chorea or ballism.

Back 3

quality

Front 4

Ataxia:

Back 4

Incoordination of muscle action; cardinal sign of cerebellar dysfunction.

Front 5

Dysmetria:

Back 5

overshooting or past-pointing in reaching tasks.

Front 6

Decomposition of movement:

Back 6

Movements broken into isolated components
(jerky)

Front 7

Intention tremor:

Back 7

-The overshooting or past-pointing of cerebellar ataxia (dysmetria) causes the limb to oscillate as it seeks to place the hand or fingers on a target. Hence, it is called an intention tremor and is to be distinguished from the tremor at rest of parkinsonism. The presence of
intention tremor, without loss of conscious position sense, is an important clue that the cerebellum or its connections are damaged.

-The nearer to the target, the greater the amplitude

Front 8

dysdiadokokinesis:

Back 8

- inability to perform rapid alternating movements such as supination/pronation movements of the hand.

Front 9

megalographia

Back 9

(large writing)

Front 10

opsoclonus:

Back 10

Wild swings of the eyes

Front 11

Other cerebellar signs:

Back 11

-Slowness in initiating or terminating movement.
-Explosive or stoccato speech (scanning speech)
-nystagmus
-hypotonia with pendular reflexes

Front 12

Cerebellar lesions do NOT cause:

Back 12

Paralysis, rigidity, obvious dyskinesias, deficits in conscious sensation, reduction in muscle strength.

Front 13

Describe how a pt with cerebellar lesion stands and walks.

Back 13

-Broad base, postural instability, drunken gait.

Front 14

When you see ataxia, how do you know it's a cerebellar lesion?

What else could it be?

Back 14

Cerebellar ataxia pts don't get worse symptoms when they close their eyes. Cerebellar patients are as ataxic with their eyes open as they are with their eyes closed. Cerebellar lesions cause no deficit in conscious sensation and patients with cerebellar lesions can accurately report the positions of their limbs in space, even with their eyes closed.

Ataxia due to dorsal column damage IF Romberg's sign is exhibited. If such a patient stands with legs together and closes the eyes, the body will sway and become unsteady. This is called Romberg's sign and indicates a sensory ataxia, not a cerebellar ataxia.

Front 15

What's up with the cerebellar tonsils and why do they suck?

Back 15

-Protuberances of the cerebellum that embrace the medulla. When there is tumor or hemorrhage in the posterior cranial fossa or if there is increased
intracranial pressure, the tonsils tend to herniate through the foramen magnum, compressing the medulla and killing the patient.

Front 16

Describe what can happen with a CP angle tumor.

Back 16

-CP angle is a common site of tumors that may involve cranial nerves V, VII and VIII (which are found together here), as well as the cerebellum and adjacent pons. A large tumor may also affect cranial nerve VI.

Front 17

Restiform body:

Back 17

ICP, input from medulla.

Front 18

Brachium pontis:

Back 18

MCP, input from pons.

Front 19

Brachium conjunctivum:

Back 19

SCP, output to midbrain.

Front 20

Deep cerebellar nuclei:

Back 20

Dentate nucleus, emboliform nucleus, globose nucleus, fastigial nucleus. (lateral to medial)

Front 21

Functional organization of the cerebellum:

Back 21

midline- vermal region
intermediate- paravermal regions
cerebellar hemispheres
flocculo-nodular lobe

Front 22

Somatotopic organization in the cerebellum:

Back 22

Axial muscles represented medially.

Distal mm laterally.

Front 23

What functional zones comprise the spinocerebellum?

Back 23

Vermal and intermediate zones. Their efferent connections are directed functionally to the spinal cord.

Front 24

The____ sends its output via the ____ nucleus and influences ____ muscles via projections to the ____ nuclei and the ____ ____ (via the____ brainstem pathway).

Back 24

vermis
fastigial
axial
vestibular
reticular formation
ventromedial

Front 25

The intermediate or paravermal zone is concerned less with axial muscles and more with ____ and ____ ____ muscles. Its output goes by way of the ____ nucleus and has particularly strong connections to the ____ nucleus and the ____ brainstem pathway. It is thought to adjust ____ ____ via its extensive sensory input from the spinal cord.

Back 25

girdle
proximal limb
interpositus
red
lateral
ongoing movements

Front 26

The lateral lobes or cerebellar hemispheres are intimately related to the ____ cortex and are sometimes referred to as the ____-cerebellum. The dentate nucleus serves as a major relay in the projection from the ____ to the ____ nucleus and, thence, to ____ cortex. The cerebro-cerebellum appears to be involved in high-level movement ____ of signals of ____ cortical origin.

Back 26

cerebral
cerebro
cerebellum
VL
motor
coordination
motor

Front 27

The ____ lobe is tucked up under the cerebellum and is related primarily to the ____ system, hence the appellation ____-cerebellum.

Back 27

flocculonodular
vestibular
vestibulo

Front 28

Scarpa's ganglion sends fibers to:

What kind of fibers?

Back 28

The flocculonodular lobe.

Primary afferent fibers that have not synapsed in the medullary vestibular nuclei.

Front 29

Unlike most cells in the cerebellar cortex, some of the cortical ____ cells of the flocculonodular lobe project directly to the ____ nuclei, without a relay in the ____ ____ nuclei.

Back 29

Purkinje
vestibular
deep cerebellar

Front 30

The flocculo-nodular lobe and vermis influence primarily the ____ brainstem pathways (____, ____); the intermediate lobe is connected with the ____ brainstem pathway (____) and the lateral cerebellum is connected with the ____ (to influence the ____ pathways and perhaps especially ____ movements of the ____).

Back 30

-ventromedial; trunk, posture
-lateral; limbs
-cortex; corticospinal; fine; hands

Front 31

Midline cerebellar tumors, such as the ____ of children, give rise to ____ ____, which may be the earliest sign of disease. Laterally placed lesions affect movements of ____ ____.

Back 31

medulloblastoma
truncal ataxia
the limbs

Front 32

There are about ____ ____ ____ axons entering the cerebellum than exiting it. These axons provide the cerebellum with current data on ____ ____ and ____ ____ for the entire body, with particularly strong influence from ____ ____, ____ ____, and the ____ ____. It uses this information to ____, ____, and ____ motor actions.

Back 32

-40 times more
-motor signals; sensory status
-muscle spindles, tendon organs, vestibular system
-adjust, coordinate, and smooth

Front 33

Spinocerebellar pathways:

Where do they travel? What kind of info do they carry? What side of cerebellum do they enter?

Back 33

Travel in lateral funiculus of spinal cord.

Carry info about body and limb posn, from skin, joint, GTOs, and spindle receptors.

Enter ipsilaterally into the cerebellum.

Front 34

In the cortico-ponto-cerebellar pathway, ____ commands from the cerebral cortex reach the cerebellum mainly via ____ but also via relays in the ____ ____ and the ____ ____ ____. This is a ____ projection, which brings together on a given side of the cerebellum the spinal and cortical input concerned with the ____ side of the body.

Back 34

motor
pons
reticular formation
inferior olivary nucleus
crossed
ipsilateral

Front 35

The input to the vermal area and flocculonodular lobe is predominantly concerned with the ____ and the ____ ____.

Back 35

trunk
vestibular system

Front 36

Input to the intermediate zone arises mainly from the ____ ____ (____ ____) and from ____ ____ by way of the ____ nuclei, and is closely related to ____ muscles.

Back 36

spinal cord
spinocerebellar tract
sensorimotor cortex
pontine
limb

Front 37

Input to the cerebellar hemispheres is from large areas of the ____ via the ____; it is believed these areas are concerned with control of the ____, though they may be involved in aspects of ____ ____ as well.

Back 37

cortex
pons
limbs
motor planning

Front 38

Inputs to the cerebellum from the spinal cord ( ____ pathways) stay on the ____ side of the body and enter largely via the ____ ____ ____ ____.

Back 38

spinocerebellar
same
ipsilateral ICP

Front 39

Corticopontine fibers originating from the LEFT cerebral hemisphere represent the RIGHT side of the body. To get to the appropriate side of the cerebellum they need to cross- they do this after they synapse in the ____. Thus, ____ fibers cross the midline and enter the ____ ____ ____ on the ____ side of the brainstem.

Back 39

pons
pontocerebellar
MCP
contralateral

Front 40

Output axons of the right dentate nucleus
cross the midline in the decussation of the ____ ____ ____ and terminate in the ____ ____ ____ of the thalamus. This nucleus then projects to the ____ motor cortex.

Back 40

SCP
left VL nucleus
left

Front 41

In the rubrospinal tract, the axons of cells in the ____ red nucleus ____ near the nucleus and descend on the ____ side of the spinal cord.

Their activity must be governed by signals from the ____ side of the cerebellum.

Back 41

LEFT
decussate
RIGHT
RIGHT

Front 42

Axons from the RIGHT interpositus nucleus cross the midline in the ___ ___ ___ to reach
the ____ red nucleus. ____ axons from the ____ red nucleus cross back to the ____ side
immediately after they leave the nucleus

Back 42

SCP
LEFT
Rubrospinal
left
right

Front 43

double decussation:

Back 43

Motor influences (via the red nucleus) from the right side of the cerebellum wind up on the IPSILATERAL side of the cord by crossing the midline twice. Thus, as far as the cerebral cortex and red nucleus are concerned, their connections with the cerebellum are identical with their
connections to the arms, i.e. crossed.

Front 44

Describe the "veto" power of the cerebellum.

What is the role of the deep cerebellar nuclei in this?

Back 44

The cerebellar cortex exercises an on-line veto over every movement pattern but the correct one (to ensure the body's next move is smooth and appropriate), which it
facilitates.

The cells of the deep nuclei transmit this ‘correct’ pattern of excitation to all of the targets of the cerebellum (e.g. the vestibular nuclei, reticular formation, red nucleus, thalamus, etc.

Front 45

Mossy fibers:

Back 45

Constitute most of the input axons to the cerebellar cortex. Many mossy fibers, particularly those from the spinal cord and vestibular nuclei, give off collaterals that excite cells in the deep cerebellar nuclei. These same mossy fibers then excite the GRANULE cells, which give rise to a single axon that rises toward the cortical surface and splits to form a PARALLEL FIBER.

Front 46

Parallel fibers:

Back 46

Some granule cells, upon being excited by mossy fibers, give rise to a single axon that rises toward the cortical surface and splits to form a parallel fiber. The parallel fibers run parallel to the folia for long distances, contacting thousands of Purkinje cells whose elaborate, flattened dendritic trees stand at right angles to the parallel fibers. The parallel fibers make excitatory synaptic contacts on the Purkinje cell’s dendrites.

Front 47

What do mossy fibers and parallel fibers have to do with the cerebellum's role in motor learning?

Back 47

Interactions between its two main inputs (mossy fibers and climbing fibers) lead to long-term SYNAPTIC PLASTICITY that underlies learning and the refinement of motor control.

Front 48

Where do climbing fibers come from to the cerebellum? Why are they called climbing?

Back 48

They come from the inferior olivary nucleus.

They get their name from their unique pattern of termination. After giving off collaterals to the deep nuclei, the climbing fibers send tendrils out along the complex dendrites of the Purkinje cells and cover them with excitatory synapses.

Front 49

How many Purkinje cells can a climbing fiber excite? How many climbing fibers does a P cell get input from?

Back 49

Climbing fibers can excite 10 P cells.
P cells get input from only 1 climbing fiber.

Front 50

What's the effect of a climbing fiber on a Purkinje cell?

What is the function of the climbing fiber?

Back 50

Strongly depolarizes the P cell.

Function unknown.

Front 51

The only excitatory cells in the cerebellar cortex:

Back 51

Granule cells.

Front 52

Purkinje, stellate, basket, and Golgi cells are all ____.

The cells of the deep nuclei make ____ synapses on their target structures.

Back 52

inhibitory

excitatory.

Front 53

These cells provide the only output axons of the cerebellar cortex. Most project to the:

Back 53

Purkinje cells.

Deep nuclei.

Front 54

Some cells in Scarpa’s ganglion project directly to the ____ ____ and ____ (as ____ fibers) and cortical Purkinje cells in these areas project directly to the ____ nuclei.

Back 54

flocculonodular lobe
vermis
mossy
vestibular