Cerebellum Flashcards
What sits in the posterior fossa, dorsal to the brainstem and the 4th ventricle
Cerebellum
True or False:
Embryologically the cerebellum is part of the pons, but the functions are so different that they are considered their own entity
True
What separates the cerebellum from the cortex
Tentorium cerebelli
True or False:
There are 2 halves to the cerebellum that are partially separated by the falx cerebelli
True
What percent of the brain volume does the cerebellum make up
10%
What percent of the brain function does the cerebellum make up
50%
What are the folds of the cerebellum called
Terminal folia
True or False:
The cortex of the cerebellum is organized into folia
True
Does the cerebellum initiate movement
No, it coordinates it
The cerebellum may also be involved in what (2)
- Cognitive functions (attention and language)
2. Regulating fear and pleasure responses
What is the most solidly established function of the cerebellum
Movement related functions
How many anatomical divisions are there in the cerebellum
3
What is the gross anatomy of the cerebellum (4)
- Cerebellar peduncles
- Folia
- Major divisions
- Deep cerebellar nuclei
What is functional anatomy of the cerebellum (4)
- Spinocerebellum
- Cerebrocerebellum
- Cerebellar vermis
- Vestibulocerebellum
What is the function of the spinocerebellum
Proprioceptive input and output
What is the function of the cerebrocerebellum
Info from the motor cortex down and back up
What is the function of the vestibulocerebellum
Vestibular nuclei to cerebellum and back out
What do the cerebellar peduncles do
Connect the cerebellum to the brainstem
True or False:
The cerebellar peduncles is composed of 3 bilateral pairs of axon tracts
True
What type of pathway is the superior cerebellar peduncles
Efferent motor pathways
What does the superior cerebellar peduncle connect with
Midbrain
What type of pathway is the middle cerebellar peduncles
Afferent pathway arising from the pontine nuclei
What is the main type of pathway of the inferior cerebellar peduncle
Afferent but does have some efferent
What does the inferior cerebellar peduncle connect to
The medulla
Which of the cerebellar peduncles is the smallest but most complex
Inferior cerebellar peduncle
What provides the main blood supply to the superior cerebellar peduncle
Superior cerebellar artery
Where does the middle cerebellar peduncle receive afferents from
Contralateral cerebral cortex inputs
What provides the main blood supply to the middle cerebellar peduncle
Anterior inferior cerebellar artery and superior cerebellar artery
Where does the inferior cerebellar peduncle receive afferents from
Ipsilateral proprioceptive input from the spinal cord
What provides the main blood supply to the inferior cerebellar peduncle
Posterior inferior cerebellar artery
What are the 3 lobes of the cerebellum
- Spinocerebellum
- Neocerebellum
- Vestibulocerebellum
What is the newest part of the cerebellum
Posterior lobe
What is the oldest part of the cerebellum
Flocculonodular lobe
What are the major longitudinal divisions of the cerebellum (3)
- Vermis
- Intermediate hemisphere
- Lateral hemisphere
What info does the vermis receive
Kinesthetic and somatosensory inputs from the spinal cord
What does the vermis project to
Fastigial nucleus
What does damage to the vermis interrupt
Posture and walking
In monkeys what does unilateral lesions of the fastigial nucleus cause
The monkey to fall to the ipsilateral side
With damage to the cerebellum what side do they lean to
Side of the damage
Where is the intermediate zone located
Between the vermis and lateral part of the cerebellum
What does the intermediate zone receive input from
Red nucleus and somatosensory info from the spinal cord
Where does the intermediate zone of the cerebellum project
Interpositus nucleus to the red nucleus
What does damage to the intermediate zone cause (3)
- Rigidity
- Difficulty in moving limbs
- Action tremor or intention tremmor
What is an intention tremor
A tremor causing movement to occur in a staggered manner during motor act
What does the lateral zone receive input from
Motor and association cortices
Where does the lateral zone send projections
Dentate nucleus to primary motor and premotor cortex
What is the function of the lateral part of the cerebellum (5)
- Ballistic movements
- Multi-joint movements
- Learning of new movements
- Timing of motor movements
- Cognitive functions
What is an example of a ballistic movement
Swinging of a bat in baseball trying to hit a fastball
What is a ballistic movement
A movement that occurs so quickly that it can not be modified by feedback
Dart experiment
People with cerebellar damage weren’t able to adjust after putting on the prism glasses while people without cerebellar damage can adjust
What is the somatotopy of the cerebellum
The head always faces the middle of the cerebellum
True or False:
Folia are made by big long sheets of cells that are folded like an accordion
True
What are within the thin layer of cells that make the folia
Several types of neurons with a highly regular arrangement
What do the folia provide
Massive signal processing capability
True or False:
Most of the cerebellar output passes through a small set of deep cerebellar nuclei
True
How many layers does the cortex (gray matter) of the folium have
3
What are the 3 layers of the cortex of the cerebellum from superficial to deep
- Molecular layer
- Purkinje layer
- Granular layer
What does the molecular layer consist of (2)
- Axons of granule cells
2. Dendrites of purkinje cells
What does the purkinje layer consist of (1)
Single layer of output cells
Is the purkinje layer excitatory or inhibitory
Inhibitory
What does the granular layer do
Excites purkinje cells
What does exciting the purkinje cells do
Increases their inhibitory effects
What are the only output neurons of the cerebellum
Purkinje cells
What do the purkinje cells do
Utilize GABA to inhibit neurons in deep cerebellar nuclei
What do the granule cells do (2)
- Utilize glutamate as an excitatory transmitter
2. Excite purkinje cells via axonal branches called parallel fibers
What are intrinsic cells of the cerebellar cortex
Granule cells
What are the inhibitory interneurons of molecular layer (2)
- Basket cells
2. Golgi cells
What do the basket cells do
Utilize GABA to inhibit purkinje cells so that motor movement occurs
What do the golgi cells do
Feedback inhibition on the mossy granule relay
What are mossy and climbing fibers
Afferents that are excitatory
What do the mossy and climbing fibers excite (2)
- Granule (mossy)
2. Purkinje (climbing fibers)
True or False:
The mossy and climbing fibers give off collaterals as they enter the cerebellum and excite the deep cerebellar nuclei
True
True or False:
All of the input to the cerebellum is excitatory
True
True or False:
All of the efferents from the cerebellum are inhibitory
True
True or False:
Basket cells wrap around the purkinje cells
True
True or False:
Purkinje cells in all 4 zones project to different deep cerebellar nuclei
True
What are the deep nuclei of the cerebellum (4)
- Dentate
- Interpositus
- Fastigial
- Vestibular nuclei
What does the denate nucleus receive input from (1)
- Purkinje cells from the lateral zone of the cerebellum
What does the interpositus nucleus receive input from (1)
- Intermediate zone
What does the fastigial nucleus receive input from (1)
- Medial zone
What does the vestibular nuclei receive input from (1)
- Flocculonodular lobe
True or False:
Damage to the lobe causes damage to corresponding deep nuclei
True
True or False:
Purkinje cells of the cerebellar cortex make tonically inhibitory connections onto the cerebellar nuclei
True
Where do all outputs from the cerebellum originate from
Deep cerebellar nuclei
True or False:
A lesion to the deep cerebellar nuclei has the same effect as a complete lesion of the entire cerebellum
True
What are the 3 main functional roles of the cerebellum
- Coordination of movement the cerebellum modulates the timing and pattern of muscle activation during movement
- Maintenance of balance/equilibrium (in conjunction with the vestibular receptors and proprioceptors)
- Regulation of muscle ton modulates spinal cord and brainstem mechanisms involved in postural control
Where is the cerebrocerebellum located
Lateral lobe
Where is the spinocerebellum located
Medial lobe
Where is the cerebellar vermis located
Medial lobe
Where is the vestibulocerebellum located
Flocculonodular lobe
What is the function of the lateral hemisphere of the cerebellum
Motor planning of the extremities
What motor pathway does the lateral hemisphere of the cerebellum influence
Lateral corticospinal tract
What is the function of the intermediate hemispheres of the cerebellum
Distal limb coordination
What motor pathways does the intermediate hemisphere of the cerebellum influence (2)
- Lateral corticospinal tract
2. Rubrospinal tract
What is the function of the vermis and flocculonodular lobe (4)
- Proximal limb and trunk coordination
- Regulation of muscle tone for posture and locomotion
- Balance
- Vestibulo-ocular reflexes
What pathways do the vermis and flocculonodular lobe influence (5)
- Anterior corticospinal tract
- Reticulospinal tract
- Vestibulospinal tract
- Tectospinal tract
- Medial longitudinal fasciculus
Cerebellar damge produces disorders in what (4)
- Movement
- Equilibrium
- Posture
- Motor learning
What is a disturbance that alters the rate, direction, and extent of voluntary movements, abnormal gait and uncoordinated movements
Ataxia
What is altered range of motion (misjudge distance)
Dysmetria
What is oscillating motion of limbs or (especially) of head, during movement, often increasing as target approaches
Intention tremor
What is nystagmus and head tilt
Vestibular signs
What is slow and uneven in attempting fast hand alternating movements
Dysdiadochokinesis
What is abnormalities in speech modulation, rate of speech, explosive scanning speech, slurred speech, irregular stress patterns, and vocalic and consonantal misarticulations
Dysarthia
What is vestibulo-ocular reflex indicative of
Motor learning deficits