15. Cerebellum lecture Flashcards
What are the functions of the cerebellum?
coordinating movements
Maintaining posture
motor learning
What are the 4 nuclei that are present within the cerebellum (the deep cerebellar nuclei)
Dont eat greasy food
Dentate
Emboliform
Globose
Fastigial
From outside to inside, what are the layers of the gray matter in the cerebellum?
Molecular
Purkinje
Granular
White matter
The _______ ______ lies next to pial surface and has few neurons with their cell bodies in basket cell and stellate cells
Molecular layer
The _____ _____ has axons of the neurons
white matter
Describe the purkinje cells
Are found in the purkinje layer between the molecular and granular layers
Outputs come from the cerebellar cortex and inhibit the cerebellum nuclei and vestibular nuclei
Have a lot of dendrites
The ______ _______ are the smallest neurons and are ONLY excitatory
granular cells
Which cells are capable of inhibiting the purkinje cells?
Stellate cells and basket cells
Describe golgi cells
inhibitory neurons and are large and scattered with short axons
Describe climbing fibers
from the inferior olive
Myelinated and excite the purkinje cells
Convey information regarding movement errors to the cerebellum
Describe mossy fibers
Originate from the spinal cord, reticular formation, vestibular system, and pontine nuclei
synapse with granulocytes
convey somatosensory, arousal, equilibrium, and cerebral cortex motor information to the cerebellum
The __________ receives info from the vestibular receptors and visual areas and sends output to the vestibular nuclei
vestibulocerebellum or the flocculonodular lobe
What are the functions of the vestibulocerebellum?
Influence eye movement and postural muscles of the head and body
What is the function of the spinocerebellum?
Controls ongoing movement via the brainstem descending tracts
takes somatosensory information from the spinal interneurons and sensorimotor cortex
Which portion of the cerebellum is important in gait?
Spinocerebellum
What is the function of the pontocerebellum or the cerebrocerebellum?
coordination of voluntary movements, planning of movements, and timing
receives input from the cerebral cortex via the pontine nuclei
How do the afferent fibers enter into the cerebellum?
Through the cerebellar peduncles
What does the dentate nucleus target with her efferents?
The red nucleus and the thalamus
What do the globose and emboli form nuclei target with her efferents?
red nucleus and thalamus
What does the fastigial nucleus target with her efferents?
Reticular formation
Vestibular nucleus
What are the mossy fibers that enter the cerebellum from the vestibular system?
Vestibular nuclei
Cranial nerve VIII
What are the mossy fibers that enter the cerebellum from the spinal cord?
Anterior spinocerebellar tract
Posterior spinocerebellar tract
Cuneocerebellar tract
What is the anterior spinocerebellar tract in charge of?
Legs and other funky movements
What is the posterior spinocerebellar tract in charge of?
Legs
What is the cuneocerebellar tract in charge of?
Arms
What are the mossy fibers that originate from the cerebral cortex?
Cortico-pontocerebellar
Corticoreticulocerebellar
What are the climbing fibers from the cerebral cortex?
cortico-olivocerebellar
What is the function of the afferent fiber pathways int eh cerebellum?
unconscious proprioception about limb movement
Describe the pathway of the posterior spinocerebellar tract
axons carrying unconscious proprioception from the lower limb
Originates in dorsal root gangla and ascends in the cuneatus gracilis
synapse in the nucleus dorsalis of clark (grey mater of C8-L2)
second order neuron ascend in the dorsolateral funicular and enters the cerebellum from the inferior cerebellar peduncle
Describe the pathway of the cuneocerebellar tract
axons carrying unconscious perception from the upper limb
Originates in DRG and ascends into the fasciculus cuneatus
synapse in the accessory cuneate nucleus in the lower medulla
2nd order neurons from the accessory cuneate nucleus ascends to the cerebellum and enters through the inferior cerebellar peduncle
Describe the afferents from the vestibular system
the juxtarestiform body and the rustiform body form the inferior cerebellar peduncle
What is special about the cuneocerebellar tract?
It crosses twice in the pathway
What comes and goes from the superior cerebellar peduncle?
Major efferents from the globose, emboli form, and dentate nuclei
Afferent fibers from the ventral spinocerebellar tract to run here too
Describe the middle cerebellar peduncle
largest peduncle
Afferent fibers from the pontine nuclei relayed to the cortex
What is the primary pathway that enters into the inferior cerebellar peduncle
Primarily afferent pathways from the spinal cord
What are the functions of the vestibulocerebellum
eye movements
neck and trunk movements
Vests cover your trunk (and neck kind of) and everyone looks at you when you wear a vest
balance equilibrium
What are the functions of the spinocerebellum?
Axial and lower extremity movements
gait and station
What are the functions of the cerebrocerebellum?
Precise, coordinated movements; mainly the upper extremity
timing, planning, coordination
In a unilateral lesion of the cerebellum which side is affected?
Ipsilateral
Describe ataxia, what sx present?
Voluntary normal strength jerky inaccurate movements wide based gait guarding fall to the side of the lesion
What does a lesion of the vestibulocerebellum cause clinically?
Nystagmus
Truncal ataxia
Truncal instability (titubation) cannot tandem walk
What does a lesion in the spinocerebellum result in?
Gait and truncal ataxia, wide, staggering base
What are the connections between the vestibular system and the flocculonodular lobe?
Vestibulocerebellum
What are the connections between the cutaneous and proprioceptive information from the spinal cord and the vermis and paravermis regions
Lesions of the spinocerebellum
______ _______ is caused by vestibulocerebellar and spinocerebellar diseases
Midline ataxia
Define titubation
tremor of the trunk in an anterior-posterior plane
Define gait ataxia
wide based, irregular steps with lateral veering (especially in the case of unilateral lesion)
What do lesions int eh cerebrocerebellum cause clinically?
Dysarthria
Ataxic gait
Decomposition of movements
Limb ataxia
Define dysarthria
slow and slurred speech that is poorly articulated
Define dysdiadochokinesia
inability to rapidly alternate movements
Define dysmetria
inability to accurately move an intended distance (can’t get to intended target)
Define action tremor
shaking of the limb with a voluntary movement
intention tremor
Dysfunction if the cerebellar hemispheres restyles in ataxia of the extremities also known as….
appendicular ataxia
What are the sx of appendicular ataxia
Hypotonia
decomposition of movement
dysmetria
dysdiachokinesia
What are common clinical findings of cerebellar ataxia
Positive romberg test
unable to stand with feet together
there is normal vibratory sense, proprioception and ankle reflexes
How are you able to tell that cerebellar ataxia is not in fact, a dorsal column issue?
Because of the normal vibratory sense, proprioception and ankle reflexes
What are the common clinical findings of sensory ataxia?
Patient is able to stand with their feet together with eyes open, but not closed
abnormal vibratory sense, proprioception, and ankle reflexes (because of the sensory component)
Differentiate between the romberg test that are found in a person with cerebellar ataxia versus sensory ataxia
People with cerebellar ataxia are not able to stand with a narrow stance and eyes open very well; romberg will be positive with eyes open
In a person with sensory ataxia, they have no problem standing with their feet together but have a positive romberg test
How do you test the vestibulocerebellum and spinocerebellum
Station
walking
tandem gait
How do you test the cerebrocerebellum
Rapid alternating movements Finger to nose Toe to finger heel to shin Rebound and recheck reflex Speech
