Cerebellum Flashcards
Organization of the gray matter of the cerebellum
Molecular layer: next to pial surface, has few neurons
cell bodies of basket cells and stellate cells
Purkinje layer: contains the purkinje cell bodies (2nd superficial layer
Granular layer: deepest layer of gray matter
contains granule cells and a few golgi cells
White matter: axons of neurons
Purkinje cell functions
Efferent cells
output crells from the cerebellar cortex
- inhibit the cerebellar nuclei and the vestibular nuclei
- neurotransmitter is GABA
Highly differentiated with many dendrites
Granule cell functions
Only excitatiory neurons
- smallest neurons
- neurotransmitter is glutamate
Stellate cell functions
axons synapse with only the purkinje cells and inhibit them
star shapped dendrites
found in the molecular layer
Golgi cell function
inhibitory neurons
neurotransmitter is GABA
largely scattered neurons with short axons
Basket cell function
their axons synapse with purkinje cells and nhibit them
found in the molecular layer
neurotransmitter is GABA
What are the climbing fibers
Afferent fibers to the Cerebellum
- from the inferior olive
- Myelinated with excitatory influence on purkinje cells
- convey info regarding movement errors to the cerebellum
What are the mossy fibers
from spinal cord, reticuar formation, vestibular system and pontine nuclei
- synapse with granulocytes
- convey somatosensory, arousal, equilibrium and cerebral cortex motor info to cerebellum
Vestibulocerebellum
Division of the spinal cord that contains the nodulus and the flocculus
functional name for the flocculonodular lobe
- receives info directly from vestibular receptors
- sends output to the vestibular nuclei
- also recieves info from visual areas
Functions to influence eye movements and postural muscles of head and body
Spinocerebellum
Functional name for vermis (medial) and paravermal (lateral) region
Somatosensory info, internal feedback from spinal interneurons and sensorimotor cortex
Functions to control ongoing movement via the brainstem descending tracts
- important for gait
- influences medial upper motor neurons and lateral upper motor neurons
Pontocerebellum
Lateral hemispheres of cerebellum
input from cerebral cortex (premotor, sensorimotor, and others via the pontine nuclei
-functions in coordination of voluntary movements, planning of movements and timing
Afferent fibers entering the cerebellum: Vestibular system
from the vestibular nuclei
Cranial nerve VIII
all via Mossy fibers
Afferent fibers entering the cerebellum: Spinal cord
Anterior spinocerebellar tract (legs)
Posterior spinocerebellar tract (legs)
Cuneocerebellar tract (Arms)
all via mossy fibers
all enter through the Inferior Cerebellar peduncle
Afferent fibers entering the cerebellum: Cerebral cortex
Cortico-pontinecerebellar (mossy)
Cortico- olivocerebellar (climbing fibers)
Cortico-reticulocerebellar (mossy)
all three enter the cerebellum through the Cerebellar peduncle
nerve pathway of the Posterior cerebellar tract
Axons are carrying unconscious proprioception from lower limb
1st order neuron enters via the dorsal root ganglion and ascends in gracile fasciculus
-synapse in nucleus dorsalis of clark (C8-L2)
2nd order neuron will ascend in posterior spinocerebellar tract and enter the cerebellum via the inferior cerebellar peduncle (restiform body)
nerve pathway of the cunecerebellar tract
Axons carrying unconscious proprioception from the upper limb
1st order neuron enters via the dorsal root ganglion and ascends in cuneate fasciculus
-synapses in accessory (external or lateral) cuneate nucleus
2nd order neuron form accessory cuneate nucleus ascends to cerebellum and enters via the inferior cerebellar nucleus (juxtarestiform body)
nerve pathway of the anterior spinocerebellar tract
carries proprioception from the lower limb and will decussate at the level and travel in the anterior spinocerebellar tract
once it reaches the pons it will decusate again as it travels through the superior cerebellar peduncle to the cerebellum
What travels through the superior cerebellar peduncle
major efferent route from the globose, emboliform, and dentate nuclei
afferent fibers from the ventral spinocerebellar tract run here aswell
what travels through the middle cerebellar peduncle
largest peduncle
afferent fibers frompontine nuclei relayed to cortex
what travels through the inferior cerebellar peduncle
Primarily afferent pathways from spinal cord
what is the function of the vestibulocerebellum
eye movements
neck and trunk movements
flocculonodular lobe
what is the function of the Spinocerebellum
Axial and lower extremity movements
gait and station
vermis and paravermal
What is the function of the cerebrocerebellum
Percise, coordinated movements of extremities
Mainly upper extremity
lateral hemispheres of the cerebellum
Information goes into the Dentate nucleus from where and goes to where
afferent is cerebrocerebellum and spinocerebellum via purkinje fibers
effernt will be to the Red nucleus and the ventral lateral thalamus
Information goes into the globose and emboliform from where and goes to where
afferent: spinocerebellum and cerebrocerebellum
efferent: red nucleus and thalamus (ventral lateral)
these two nuclei can also be called the interposed nuclei
Information goes into the fastigial nucleus from where and goes to where
Afferent: spinocerebellum, vestibulocerebellum
efferent: Reticular formation and vestibular nucleus
what is some information in the cerebellum that skips going to the deep nuclei of the cerebelllum
some afferents from the vestibulocerebellum will skip going to the deep nuclei and will travel on the purkinje fibers all the way to the vestibular nucleus
What are the 4 deep nuclei of the Cerebellum
Fastigial, globose, emboliform, and the dentate
how will cerebellar unilateral lesions affect the body
affects the ipsilateral side
Ataxia:
common to all lesions of cerebellum
Voluntary normal strength, jerky and inaccurate movements not associated with hyperstiffness
tend to fall to the side of the lesion
Lesions to the vestibulocerebellumq
connections between the vestibular system and the flocculonodular lobe
nystagmus
Truncal ataxia: difficulty maintaining sitting and standing balance
truncal instabillity
-cant tandem walk
Lesions of the spinocerebellum
connections between the cutaneous and proprioceptive information coming from the spinal cord to the vermis and paravermis regions
gait and truncal ataxia: wide base, staggering base
Midline ataxia
ataxic syndromes caused by vestibulocerebellar and spinocerebellar disease are called midline ataxia:
Truncal instabillity
-titubation: tremor of the trunk
-gait ataxia: wide base, irregular steps with lateral veering
Equilibratory (gait) ataxias
-gait ataxia: wide based, irregular steps with lateral veering
Lesions of the cerebrocerebellum
Dysarthria: slurred, poorly articulated speech
Ataxic gait
-staggering ataxic gait with tendency to fall toward side of the lesion
Decomposition of movements
Limb ataxia manifestations:
Dysdiadochokinesia: inability to rapidly alternate movements
Dysmetria: inability to accurately move an intended distance
Action tremor: shaking of the limb during voluntary movement
Cerebellar Ataxia
romberg test is positive
unable to stand with feet together
-with or without eyes open
normal vibratory sense, proprioception and ankle reflexes
Sensory Ataxia
Can stand with feet together with eyes open, but not closed (positive romberg test)
abnormal vibratory sense, proprioception and ankle reflexes
How to test for the vestibulocerebellum and spinocerebellum
station
walking
tandem gait
How to test for the cerebrocerebellum
rapid alternating movements finger to nose toe to finger heel to shin rebound and check reflex speech
