(15) Cerebellum

Question 1

(location)

1. the term cerebellum literally means what?
2. Cerebellum is located where relative to brain-stem?
3. Connected to the brainstem by how many pairs of cerebellar peduncles?

Answer 1

1. little brain
2. dorsal
3. three

Question 2

(Functions)

1-3. What are the three major functions of the cerebellum?

Answer 2

1. Coordiation of Movement (the cerebellum controls the timing and pattern of muscle activation during movement)
2. Maintenance of Equilibrium (in conjunction with the vestibular system)
3. Regulation of muscle tone (modulates spinal cord and brain stem mechanims involved in postural control)

Question 3

(Dysfunction)

1-4. Damage to the cerebellum results in what four things?

Answer 3

1. Ataxia
2. Dysmetria
3. Intention Tremor
4. Vestibular Signs

Question 4

(dysfunction)

1. What is ataxia? characterized by what?

Answer 4

1. disturbance that alters the direction and extent of voluntary movements; abnormal gait and uncoordinated muscle movements

Question 5

(dysfunction)

1. What is dysmetria? limbs are lifted too high or not high enough?

Answer 5

1. altered range of motion (misjudge distance); either

Question 6

(dysfunction)

1. What is an intention tremor?

Answer 6

1. osciallation motion, esp of the head, during movement

Question 7

(dysfunction)

1. what are vestibular signs?

Answer 7

1. nystagmus, head tilt

Question 8

(Gross Anatomical Organization)

1. Internal organization of cerebellum similar to what?

(name that section)

2. surface grey matter; divided by what into what?
3. internal
4. three pairs located in the white matter; name them from medial to lateral

Answer 8

1. cerebral hemisphere
2. cerebellar cortex; sulci into folia (small folds)
3. white matter
4. cerebellar nuclei; fastigial, interpositus, and dentate

Question 9

(gross anatomical organization)

1. How many cerebellar lobes?

2-4. name them

Answer 9

1. 3
2. rostral lobe
3. caudal lobe
4. flocculonodular lobe

Question 10

(cerebellar lobes)

1. Rostral lobe = ?
2. related to what? assocatied with what?
3. Damage results in what?

Answer 10

1. spinocerebellum (paleocerebellum)
2. spinal cord; postural tone
3. forelimb hyperextension and hindlimb hip flexion

Question 11

(cerebellar lobes)

1. Caudal Lobe = ?

2-4. Damage results in what 3 things?

Answer 11

1. cerebrocerebellum (neocerebellum)
2. hypotonia (reduced muscle tone)
3. hypermetria (ataxia where movements overreach)
4. intention tremor

Question 12

(cerebellar lobes)

1. Flocculonodular Lobe = ?
2. Associated with what?
3. involved in what?
4. Damage results in what three things?

Answer 12

1. vestibulocerebellum
2. vestibular system
3. control of eyes movements and balance
4. dysequilibrium, wide-based gait, and nystagmus

Question 13

(gross anatomical organization)

(Longitudinal Zones)

There are three

1-3. name them

Answer 13

1. Vermis
2. Paravermis
3. Hemispheres

Question 14

(gross anatomical organization)

(Longitudinal Zones)

1. The most medial portion of the cerebellum
2. associated with what nucleus?
3. concerned with what?

Answer 14

1. vermis
2. fastigial nucleus
3. regulation of muscle tone for posture and locomotion

Question 15

(gross anatomical organization)

(Longitudinal Zones)

1. intermediate part of the cerebellum
2. Associated with what underlying nucleus
3. participates in control of what by utilizing what generated by what to correct what?

Answer 15

1. paravermis
2. interpositus nucleus
3. an evolving movement by utilizing proprioceptive sensory info generated by the movement itself to correct errors in movement

Question 16

(gross anatomical organization)

(Longitudinal Zones)

1. The largest and most lateral part of the cerebellum
2. Associated with what nucleus
3. Influences the output of what that permits what that are important for what?

Answer 16

1. Hemispheres
2. dentate nucleus
3. Influences the output of the motor cortex and thus permits fine, delicate adjustments in muscle tone that are important for skilled movements

Question 17

(gross anatomical organization)

(cerebellar peduncles)

1. Names by what?

2-4. Name them

Answer 17

1. position
2. Caudal Cerebellar Peduncle
3. Middle Cerebellar Peduncle
4. Rostral Cerebellar Peduncle

Question 18

(gross anatomical organization)

(cerebellar peduncles)

1. Connects the cerebellum with the medulla
2. Contains what fiber typs?

Answer 18

1. caudal cerebellar peduncle
2. afferent and efferent fibers

Question 19

(gross anatomical organization)

1. connects cerebellum with the pons
2. what types of fibers? arising from where and terminating where?

(cerebellar peduncles)

Answer 19

1. middle cerebellar peduncle
2. entirely afferent fibers (axons); arise from pontine nuclei; terminate in cerebellum

Question 20

(gross anatomical organization)

1. Connects the cerebellum with the midbrain
2. Primarily a what type of fiber bundle
3. carrying axons out of where to other brain regions

(cerebellar peduncles)

Answer 20

1. Rostral cerebellar peduncle
2. efferent fiber bundle
3. out of the cerebellum

Question 21

(gross anatomical organization)

1. Cerebellar cortex = ?
2. How many layers?

3-5. name them

(cerebellar cortex)

Answer 21

1. the surface gray matter of the cerebellum,
2. three
3. molecular layer
4. purkinje cell layer
5. granule cell layer

Question 22

(gross anatomical organization)

1. the most superficial layer

2-3. consists of what two things?

(cerebellar cortex)

Answer 22

1. molecular layer
2. axons of granule cells (termed parallel fibers)
3. dendritic processes of purkinje cells

Question 23

(gross anatomical organization)

1. the middle layer of the cortex
2. consisting of what?

(cerebellar cortex)

Answer 23

1. purkinje cell layer
2. single layer of large nueronal cell bodies (termed purkinje cells)

Question 24

(gross anatomical organization)

1. the deepest layer of the cerebellar cortex
2. found adjacent to what?
3. consists predominantly of what called what?

(cerebellar cortex)

Answer 24

1. granule cell layer
2. white matter
3. small neurons called granule cells

Question 25

(cell types and afferent fibers of the cerebellar cortex) (name that cell type) 1. the only output neurons from the cortex. utilize what as an inhibitory NT? inhibit neurons where?

Answer 25

1. Purkinje Cells; GABA; deep in the cerebellar nuclei

Question 26

(cell types and afferent fibers of the cerebellar cortex) ## Footnote (name that cell type) 1. intrinsic cells of the cerebellar cortex 2. utilize what as an excitatroy NT 3. excite what via what?

Answer 26

1. granule cells 2. glutamate 3. Purkinje cells via parallel fibers

Question 27

(cell types and afferent fibers of the cerebellar cortex) ## Footnote (name that cell type) 1. inhibitiory interneurons 2. utilize what to inhibit purkinje cells?

Answer 27

1. basket cells 2. GABA

Question 28

(cell types and afferent fibers of the cerebellar cortex) ## Footnote (name that cell type) 1. arise from the olivary nucleus and terminate on purkinje cells 2. thought to use what two things as excitatory transmitters?

Answer 28

1. climbing fibers 2. glutamate and aspartate

Question 29

(cell types and afferent fibers of the cerebellar cortex) ## Footnote (name that cell type) 1. Fibers thatn enter the cerebellum from all other sources 2. except what? 3. synapse on what to excite them?

Answer 29

1. mossy fibers; ollivary nucleus 2. olivary nucleus (spinal cord, pontine nuclei) 3. granule cells

Question 30

(Major Cerebellar Inputs (axons entering the cerebellum) 1. what are the two types?

Answer 30

1. climbing fiber inputs and mossy fiber inputs

Question 31

(Major Cerebellar Inputs (axons entering the cerebellum) 1. Climbing fiber inputes = ? 2. Arise exclusively from what? 3. Have a powerful excitatory effect on what?

Answer 31

1. olivocerebellar fibers 2. the olivary nucleus of the caudal medulla 3. the purkinje cells on which they synapse

Question 32

(Major Cerebellar Inputs (axons entering the cerebellum) (Mossy Fiber inputs) There are three types 1-3. name them

Answer 32

1. vestibulocerebellar fibers 2. spinocerebellar fibers 3. cerebropontocerebellar fibers

Question 33

(Major Cerebellar Inputs (axons entering the cerebellum) ## Footnote (Mossy Fiber inputs) 1. These arise directly from the vestibular nerve and vestibular nuclei 2. project primarily to where? 3. helps coordinate what?

Answer 33

1. vestibulocerebellar fibers 2. flocculonodular lobe and fastigial nucleus 3. head and eye movement

Question 34

(Major Cerebellar Inputs (axons entering the cerebellum) ## Footnote (Mossy Fiber inputs) 1. arise from the spinal cord 2. travel to cerebellum via what? 3. terminate predominantly where? 4. Makes cerebellum aware of what via what

Answer 34

1. spinocerebellar fibers 2. spinocerebellar and ventral spinocerebellar tracts 3. in the rostral lobe 4. aware of ongoing movements via proprioceptive input from muscle spindles and joint receptors

Question 35

(Major Cerebellar Inputs (axons entering the cerebellum) ## Footnote (Mossy Fiber inputs) 1. Arise from pyriamidal cells in the cerebral cortex 2. synapse where? which then send their axons where via what (which form what)? 3. Serves what function?

Answer 35

1. cerebropontocerebellar fibers 2. in the pontine nuclei; the contralateral cortex via pon- tocerebellar fibers (the middle cerebellar peduncle) 3. alerts the cerebellum about anticipated movement

Question 36

**(KEY CONCEPT)** 1. The cerebellum must monitor ongoing movements in order to correct what? 2-4. It receives input from what three places?

Answer 36

1. erros in movement 2. from proprioreceptors that relay info via the spinal cord (spinocerebellar tracts) 3. semicircular canals and utricle and saccule of the inner ear (vestibulospinal fibers) - (provide info related to body or head movement) 4. cerebral cortex (cerebropontocerebellar fibers) and red nucleus to determine what the trajectory related to thwat the ongoing movement should be.

Question 37

(Major cerebellar outputs (arise from neurons in deep cerebellar nuclei) There are three types 1-3. name them

Answer 37

1. fastigial nucleus projections 2. interpositus nucleus projections 3. dentate nucleus projections

Question 38

(major cerebellar outputs (arise from neurons in deep cerebellar nuclei)) 1. go to vestibular nuclei and reticular formation 2. via vestibulospinal and reticulo-spinal tracts, the projections ultimately influence what related to what?

Answer 38

1. fastigial nucleus projections (via caudal peduncle) 2. primarily extensor muslces related to maintaining posture and balance

Question 39

(major cerebellar outputs (arise from neurons in deep cerebellar nuclei)) 1. go to red nucleus to influence rubrospinal tract activity 2. projections make corrections related to what?

Answer 39

1. interpositus nucleus projections (via rostral peduncle) 2. related to gross movements of the animal

Question 40

(major cerebellar outputs (arise from neurons in deep cerebellar nuclei)) 1. go to thalamus to influence output from the motor cortex 2. projections make delicate adjustments related to what?

Answer 40

1. dentate nucleus projections (via rostral peduncle) 2. fine, skilled movements

Question 41

(clinical abnormalities) 1. The most salient symptoms of the cerebellar dysfunction are what related? Lesions of the cerebellum (i.e., damage to cerebellar input, cerebellar output, or cerebellar cortex) result in symptoms that occur because the cerebellum’s normal function is interrupted. Thus ataxia, dysmetria, and intention tremor are the result of interference with the cerebellums normal role in the coordination of movement and in the maintenance of equilibrium and appropriate muscle tone. 2. In general, damage to the midline portion may disrupt what? 3. whereas damage localized more laterally is more likely to disrupt what?

Answer 41

1. motor related (the specific symptoms depend on which part of the cerebellum is involved and how it is disrupted) 2. whole-body movements 3. fine movements of the paws or limbs (more skilled movements)

Question 42

(clinical abnormalities) 1. cerebellar disorders usually result from what five things?

Answer 42

1. tumors 2. viral infections (encephalitis; canine distemper) may occur in utero 3. heavy metal poisoning 4. genetic orders 5. trauma

Question 43

(clinical abnormalities) (lesions or damage) 1. Can small lesions produce no signs or only transient signs? Why is this?

Answer 43

1. yes; relatively large margin of physiologic safety built into the system (small deficits often be compensated for by other parts of brain)

Question 44

(clinical abnormalities) ## Footnote (lesions or damage) 1. Lesions of cerebellar hemispheres result in what? 2. on what side

Answer 44

1. loss of muscular coordination and jerky puppet like movments of the limbs (dysmetria) on 2. ipsilateral side (same side as lesion)

Question 45

(clinical abnormalities) ## Footnote (lesions or damage) 1. Lesions of the cerebellar vermis result in what?

Answer 45

1. truncal termor and gait ataxia (a splayed stance and swaying of the body while walking)

Question 46

(clinical abnormalities) ## Footnote (lesions or damage) 1. Lesions of the flocculonodular lobe (vestibule cerebellum) result in what? 2. As you might expect these symptoms are similar to what you would observe with damage to what? 3. When you see animals in the clinic that exhibit ataxia, dysmetria, intention tremor and/or vestibular signs, you should consider what?

Answer 46

1. nystagmus, head tilt, tight circling, and falling 2. the vestibular system 3. cerebellar damage as a major contributor to the symptoms you observe