17. Cerebellum Flashcards
what are the functions of the cerebellum
coordinating movement (fluid movement)
maintaining posture
motor learning (procedural memory)
what is the organization of the gray matter in the cerebellum
- Molecular layer: next to pia; cell bodies of basket & stellate cells
- Purkinje layer: purkinje cell bodies
- Granular layer: next to white matter; granule cells & golgi cells
what is the fxn of purkinje cells
Efferent to deep cerebellar nuclei & vestibular nuclei
= inhibitatory (GABA)
what is the function of granule cells
small neurons that excite
via glutamate
what are the functions of stellate cells
synapse ONLY w/ purkinje
-inhibit
what is the function of golgi cells
inhibitory neurons - use GABA
what is the function of basket cells
synapse w/ purkinje cells & inhibit via GABA
what are the two types of afferent fibers in the cerebellum
- Climbing fibers- from inferior olive; myelinated w/ excitatory influence of purkinje ==> movement error correction
- Mossy fibers: from sp. cord, RF, vestibular system & pontine nuclei; synapse with granulocytes = convey somatosensory, arousal, equilibrium & cortex motor info
what is the vestibulocerebellum
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
what is the spinocerebellum
fxnal division of cerebellum
= somatosensory info, internal feedback from spinal interneurons & sensorimotor cortex
= control ongoing movement (imp for gait); axial & LE movement
what is the pontocerebellum
fxnal unit of cerebellum
input from cortex via pontine nuclei then into cerebellum
= coordination of voluntary movements, planning and timing movement : mainly UE
what are the afferent fibers entering the cerebellum from the vestibular system
vestibular nuclei
cranial N 8
-both mossy fibers
what are the afferent fibers entering the cerebellum from the sp. cord
ant. spinocerebellar tract: legs
post. spinocerebellar tract: legs
cuneocerebellar tract: arms
all 3 = mossy fibers
what are the afferent fibers entering the cerebellum from the cerebral cortex
cortio-pontocerebellar - mossy
cortico-reticulocerebellar - mossy
cortico-olivocerebellar - climbing
what is the fxn of post spinocerebellar tracts & basic path
=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
what is the fxn of the cuneocerebellar tract & what is its basic path
=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
what is the path of the ant. spinocerebellar tract
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
what is the fxn of each portion of the cerebellar peduncle
- superior: efferents from globus, emoliform & dentate &&& afferent from ant. spinocerebellar tract
- Middle: afferent from pontine nuclei
- inferior: primarily afferents from sp. cord
what is the path of efferent fibers from the fastigial nucleus
- to vestibular nuclei –> vestibulospinal tract
- to pontine/medullaty RF -> reticulospinal tracts
what is the path of efferent fibers from dentate nucleus
- out through superior cerebellar peduncle –> VL of thalamus –> cortex
- out through superior cerebellar peduncle –> red nucleus –> rubrospinal tract
what is the efferent path for fibers from interposed nuclei
- –> red nucleus –> rubrospinal tract
- also can get info from inf. olivary nucleus via olivocerebellar fibers –> then project to red nucleus
- –> VL of thalamus –> cortex
unilateral lesions of the cerebellum will affect
ipsilateral side
what is ataxia
voluntary, normal strength, jerky/inaccurate movements (not associated with hyperstiffness)
–> wide based gait, gaurding & lean toward side of lesion (if unilateral)
lesions of vestibulocerebellum
nystagmus
truncal ataxia
truncal instablity (titubation) - cant tandom walk
-tremor of trunk/head in ant/pot direction
lesions of the spinocerebellum lead to
jerky gait & trunal ataxia
- wide/staggering base
- diff to tandem walk
what is midline ataxia
caused by vestibulocerebellar & spinocerebellar disease
= truncal instability; titubation (tremor of trunk in ant-pot direction)
-gait ataxia - wide base, irregular steps w/ lateral veering
lesions of the cerebrocerebellum
dysarthria
ataxic gait
- dysdiadochokinesia
- dysmetria followed by action tremor
what is apendicular ataxia
prob in cerebrocerebellum
ataxia of speech
hypotonia
decomp of movement
dysmetria
dysdiadochokinesia
what are the differences btn cerebellar ataxia & sensory ataxia
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
