17. Cerebellum

Question 1

what are the functions of the cerebellum

Answer 1

coordinating movement (fluid movement)

maintaining posture

motor learning (procedural memory)

Question 2

what is the organization of the gray matter in the cerebellum

Answer 2

1. Molecular layer: next to pia; cell bodies of basket & stellate cells
2. Purkinje layer: purkinje cell bodies
3. Granular layer: next to white matter; granule cells & golgi cells

Question 3

what is the fxn of purkinje cells

Answer 3

Efferent to deep cerebellar nuclei & vestibular nuclei

= inhibitatory (GABA)

Question 4

what is the function of granule cells

Answer 4

small neurons that excite

via glutamate

Question 5

what are the functions of stellate cells

Answer 5

synapse ONLY w/ purkinje

-inhibit

Question 6

what is the function of golgi cells

Answer 6

inhibitory neurons - use GABA

Question 7

what is the function of basket cells

Answer 7

synapse w/ purkinje cells & inhibit via GABA

Question 8

what are the two types of afferent fibers in the cerebellum

Answer 8

1. Climbing fibers- from inferior olive; myelinated w/ excitatory influence of purkinje ==> movement error correction
2. Mossy fibers: from sp. cord, RF, vestibular system & pontine nuclei; synapse with granulocytes = convey somatosensory, arousal, equilibrium & cortex motor info

Question 9

what is the vestibulocerebellum

Answer 9

fxnal division

-recieve info directly from vestibular receptors/visual areas & sends output to vestibular nuclei

= influence eye movement, neck & trunk movement, postural Ms, balance & equilibrium

Question 10

what is the spinocerebellum

Answer 10

fxnal division of cerebellum

= somatosensory info, internal feedback from spinal interneurons & sensorimotor cortex

= control ongoing movement (imp for gait); axial & LE movement

Question 11

what is the pontocerebellum

Answer 11

fxnal unit of cerebellum

input from cortex via pontine nuclei then into cerebellum

= coordination of voluntary movements, planning and timing movement : mainly UE

Question 12

what are the afferent fibers entering the cerebellum from the vestibular system

Answer 12

vestibular nuclei

cranial N 8

-both mossy fibers

Question 13

what are the afferent fibers entering the cerebellum from the sp. cord

Answer 13

ant. spinocerebellar tract: legs
post. spinocerebellar tract: legs

cuneocerebellar tract: arms

all 3 = mossy fibers

Question 14

what are the afferent fibers entering the cerebellum from the cerebral cortex

Answer 14

cortio-pontocerebellar - mossy

cortico-reticulocerebellar - mossy

cortico-olivocerebellar - climbing

Question 15

what is the fxn of post spinocerebellar tracts & basic path

Answer 15

=unconscious proprioception from lower limb

1 neuron enter via DRG –> go up in gracile fasciculus –> synapse at dorsalis of clark (C8-L2) –> 2 neuron go up in post. spinocerebellar tract –> enter cerebellum through inf cerebellar peduncle

Question 16

what is the fxn of the cuneocerebellar tract & what is its basic path

Answer 16

=unconscious proprioception from upper limb

-1st neuron enter through DRG and go up cuneate fasciculus –> synapse at acessory cuneate nucleus –> 2nd neuron goes up to cerebellum and enters via inf. cerebellar peduncle

Question 17

what is the path of the ant. spinocerebellar tract

Answer 17

start at border zone @ grey matter –> cross and ascend up in ant. spinocerebellar tract –> get to sup cerebellar peduncle and cross again and enter the cerebellum

Question 18

what is the fxn of each portion of the cerebellar peduncle

Answer 18

• superior: efferents from globus, emoliform & dentate &&& afferent from ant. spinocerebellar tract
• Middle: afferent from pontine nuclei
• inferior: primarily afferents from sp. cord

Question 19

what is the path of efferent fibers from the fastigial nucleus

Answer 19

1. to vestibular nuclei –> vestibulospinal tract
2. to pontine/medullaty RF -> reticulospinal tracts

Question 20

what is the path of efferent fibers from dentate nucleus

Answer 20

1. out through superior cerebellar peduncle –> VL of thalamus –> cortex
2. out through superior cerebellar peduncle –> red nucleus –> rubrospinal tract

Question 21

what is the efferent path for fibers from interposed nuclei

Answer 21

1. –> red nucleus –> rubrospinal tract
   
   1. also can get info from inf. olivary nucleus via olivocerebellar fibers –> then project to red nucleus
2. –> VL of thalamus –> cortex

Question 22

unilateral lesions of the cerebellum will affect

Answer 22

ipsilateral side

Question 23

what is ataxia

Answer 23

voluntary, normal strength, jerky/inaccurate movements (not associated with hyperstiffness)

–> wide based gait, gaurding & lean toward side of lesion (if unilateral)

Question 24

lesions of vestibulocerebellum

Answer 24

nystagmus

truncal ataxia

truncal instablity (titubation) - cant tandom walk

-tremor of trunk/head in ant/pot direction

Question 25

lesions of the spinocerebellum lead to

Answer 25

jerky gait & trunal ataxia

• wide/staggering base
• diff to tandem walk

Question 26

what is midline ataxia

Answer 26

caused by vestibulocerebellar & spinocerebellar disease

= truncal instability; titubation (tremor of trunk in ant-pot direction)

-gait ataxia - wide base, irregular steps w/ lateral veering

Question 27

lesions of the cerebrocerebellum

Answer 27

dysarthria

ataxic gait

• dysdiadochokinesia
• dysmetria followed by action tremor

Question 28

what is apendicular ataxia

Answer 28

prob in cerebrocerebellum

ataxia of speech

hypotonia

decomp of movement

dysmetria

dysdiadochokinesia

Question 29

what are the differences btn cerebellar ataxia & sensory ataxia

Answer 29

cerebellar: postive Romberg test; unable to narrow gait w/ or w/o eyes closed; BUT normal vibratory sense, proprioception & ankle reflex
sensory: able to stable with feel together but not when eyes are closed; AND abnormal vibratory sense, proprioception & ankle reflexes