Cerebellum

Front 1

Flocculonodular lobe

Back 1

-major input/output is with vestibular apparatus

-oldest part phylogenetically

-influences the vestibulospinal and recticospinal tracts

-concerned with balance

Front 2

Intermediate zone

Back 2

-major input/output is with the spinal cord

-second oldest phylogenetically

-influences the rubrospinal tract

-concerned with posture & muscle tone

Front 3

Lateral zone

Back 3

-major input/output is with cerebral cortex

-influences the cerebral cortex via the thalamus and the rubrospinal tract

-concerned with muscular coordination

Front 4

Dentate, emboliform, globose, and fastigial nucleus

Back 4

contain large multipolar neurons whose axons form the cerebellar outflow in the superior & inferior cerebellar peduncles.

Front 5

Dentate inputs

Back 5

are from lateral parts of cerebellar hemispheres

Front 6

Globose/ emboliform receive inputs from

Back 6

intermediate part of hemisphere

Front 7

Fastigial inputs

Back 7

from vermis and flocculondular lobe

Front 8

The white matter is made up of 3 group fibers

Back 8

1. intrinsic

2. afferent

3. efferent

Front 9

Intrinsic fibers

Back 9

-do not leave the cerebellum

-connect different folia of the cerebellar cortex and vermis on the same side

-some connect the 2 hemispheres

Front 10

Afferent fibers

Back 10

-form the greater part of the white matter, and proceed to the cortex

- in the cortex, they lose their myelin sheath and end as either climbing or mossy fibers

Front 11

efferent fibers

Back 11

-are the output of the cerebellum

-they are the axons of the neurons of the cerebellar nuclei upon which the axon of the Purkinje cells synapse

Front 12

most of the afferent fibers pass through

Back 12

the inf. and the middle cerebellar peduncles

Front 13

most of the efferent fibers pass through

Back 13

the sup. and the middle cerebellar peduncles

Front 14

Climbing fibers

Back 14

-are the terminal fibers of the oliviocerebellar tracts

-they enter the molecular layer of the cortex, where they branch and make multiple synaptic contacts with only one Purkinje cell.

-a few side branches synapse with adjacent stellate and basket cells

Front 15

Mossy fibers

Back 15

-are the terminal fibers of all the other cerebellar afferents

-they have multiple branches and exert a much more excitatory effect

-Ex: a single mossy fiber may stimulate thousands of Purkinje cells through the granule cells

-the remaining cells in the cerebellar cortex, the Golgi, basket and stellate cells limit the area excited by Purkinje cells by inhibiting these

Front 16

What are the cerebellar afferent fibers from the cerebral cortex?

Back 16

1. Corticopontocerebellar pathway

2. Cerebro-oliviocerebellar pathway

3. Cerebro-reticulocerebellar pathway

4. Vestibulocerebellar tract

Front 17

Corticopontocerebellar function

Back 17

control from cerebral cortex

Front 18

Cerebro-olivocrebellar func.

Back 18

control from cerebral cortex

Front 19

Cerebro-reticulocerebelalr func.

Back 19

control of voluntary movements

-cerebral cortex informs the cerebellum about initiation of the movement, so that can be monitored by the cerebellum

Front 20

Vestibulocerebellar func.

Back 20

controlling the position and movement of the head.

Front 21

Other afferent fibers

Back 21

-ant. and post. spinocerebellar tracts convey info about muscle and joints--> end as mossy fibers

Front 22

Major input source

Back 22

-is corticopontine systems that originate in motor cortex, primary sensory cortex, and visual cortex and relay through pontine nuclei.

-pontocerebellar fibers then decussate and enter cerebellum via middle cerebellar peduncle.

Front 23

What are the cerebellar efferent fibers?

Back 23

1. Globose-emboliform-rubral pathway

2. Dento-thalamic pathway

3. Fastigial Vestibular pathway

4. Fastigial Reticular pathway

Front 24

Globose-emboliform-rubral func.

Back 24

controlling ipsilateral motor activity

Front 25

Dento-thalamic func.

Back 25

controlling ipsilateral motor activity

Front 26

Fastigial Vestibular func.

Back 26

controlling ipsilateral extensor tone

Front 27

Fastigial Reticular func.

Back 27

controlling ipsilateral muscle tone.

Front 28

Lesions of lateral cerebellum affect

Back 28

distal limb coordination

Front 29

medial lesions affect

Back 29

mainly trunk control, posture, balance, and gait

Front 30

cerebellar deficits occur__________ to the lesion

Back 30

ipsilateral

Front 31

Acute lesions

Back 31

produce sudden, severe signs and symptoms, but there is considerable recovery perhaps due to compensation of loss of cerebellar function by other areas of the CNS

Front 32

Chronic lesions

Back 32

such as slow growing tumor, produce much less severe symptoms and signs that those of acute lesions

Front 33

Cerebellar lesion S&S

Back 33

-hypotonia

-postural changes and alteration of gait

-ataxia (disturbances of voluntary mov.)

-intension tremor

-Dysdiachokinesia

-Disturbances of reflexes

-Disturbances of ocular movement: nystagmus

-Disorders of speech

Front 34

Ataxia

Back 34

-refers to disordered contractions of agonist and antagonist muscles and lack coordination between movements at diff. joints typically seen in patients with cerebellar lesions

-ataxia movements have irregular, wavering course consisting ofcontinuous overshooting, overcorrecting and then overshooting again around the intended trajectory.

Front 35

Truncal Ataxia

Back 35

-caused by lesions in vermis (controls medial m. groups (posture/equillibrium)

-produce wide-based, unsteady, staggering gait

-patients often fall toward the side of the lesion

-in severe cases patients cannot even sit up w/o assistance

Front 36

Appendicular ataxia

Back 36

-lesions of intermediate and lateral regions of cerebellum

-ex: finger to nose text

Front 37

Common causes of acute ataxia

Back 37

-toxin ingestion

-ischemic or hemorrhagic stroke

Front 38

Common cause chronic ataxia

Back 38

-brain metastases

-alcoholism

-Multiple sclerosis (MS)

-degenerative disorders of cerebellum

Front 39

Sensory ataxia

Back 39

-occurs when dorsal column- medial lemniscus pathway is damaged

-impaired proprioception occurs

-function improves with visual input

-worsens with eyes closed or in the dark

Front 40

Chronic ataxia in children is often caused by

Back 40

-cerebellar astrocytma, medulloblastoma, or Friederich's ataxia

Front 41

Vascular supply of cerebellum

Back 41

-post. inf. cerebellar a.

-ant. inf. cerebellar a.

-sup. cerebellar a.

Front 42

Cerebellar a. infarcts are more common in

Back 42

-PICA, SCA, and AICA

Front 43

symptoms of cerebellar infarcts

Back 43

vertigo, nausea, vomiting, horizontal nystagmus, limb ataxia, unsteady gait, headache

Front 44

Lateral medullar infarct

Back 44

-can cause cerebellar symptoms due to damage of cerebral peduncles, however, in these cases, medullary symptoms will also occur including Horner's syndrome.

Front 45

Why is swelling in post. fossa life threatening?

Back 45

Due to potential for brainstem compression

Front 46

Cerebellar cortex is divided into 3 layers

Back 46

-Molecular layer (external)

-Purkinje cell layer (middle)

-Granular layer (internal)

Front 47

Molecular layer

Back 47

-stellate cells

-basket cells

Front 48

Purkinje cell layer

Back 48

-large neurons

-dendrites--> pass into molecular level

-axons--> pass through granular layer

Front 49

Granular layer

Back 49

-small granular cells

-golgi cells--> send dendrites to the molecular layer and their axons synapse w/ the dendrites of the granular cells