Cerebellum (Keim) Flashcards
General concepts about the cerebellum:
Receives input but does NOT interpret it
Rarely results in muscle paralysis
Has motor and procedural learning components
Talks to other tracts
Functions of cerebellum
Coordination, posture (+ the motor and procedural learning)
Layers of gray matter in the cerebellum and what do they contain?
Molecular (basket cells and stellate cell bodies)
Purkinje (has the purkinje cell bodies)
Granular (has granule cells and few Golgi cells)
What are purkinje cells?
Output cells (efferents that take info from cerebellum to muscles
Inhibit the cerebellar and vestibular nuclei
GABA is NT(coz inhibitory)
What are granule cells?
Excitatory, NT is glu
What are other inhibitory cells in the cerebellar grey matter and what do they inhibit?
What is their NT?
Stellate (inhibits purkinje) - in molec layer
Golgi
Basket (inhibits Purkinje) - in molec layer
-GABA
What are climbing fibers?
where they come from, what they excite, function
Arise from inferior olive. Afferents that excite the purkinje and deep cerebellar nuclei. Sends info about movement errors to cerebellum
What are mossy fibers?
where they come from, what they excite, function
Arise from spinal cord, not the olive. Afferents excite granule cells and deep cerebellar nuclei
Sends info about somatosensory, arousal, equilibrium and cerebral cortex motor info to cerebellum so we can do the right movement
Vestibulocerebellum
Receives input from?
Output to?
Overall general function?
Aka flocculonodular lobe.
- vestibular apparatus and vestibular nuclei
- back to vestibular nuclei which….
- influence eye movements and postural muscles of head and body (where am I at?)
Spinocerebellum
Info from?
Overall general function?
Aka vermis and the surrounding paravermal region
Somatosensory from spinal interneurons and sensorimotor cortex
Influence medial and lateral UMNs which control ongoing movement. Important in gait
Pontocerebellum/cerebrocerebellum
Input from?
Function?
Cerebral cortex (motor and sensory etc.) via the pontine nuclei Coordination of voluntary movements, planning and timing of movements
Draw the big pictures schematic of the cerebellar pathways
Ok
What afferents send input to the cerebellum?
Via which fibers?
Vestibular system (vestibular nuclei, CN VIII) Spinal Cord (anterior and posterior spino-, cuneo-) Cerebral cortex (cortico ponto-,olivo-, reticulo-)
*all via mossy fibers, except cortico-olivo-cerebellar (climbing fibers since coming from olive)
Afferents coming from the vestibular system and spinal cord enter via…
Afferents coming from the cortex enter via …
- internal cerebellar peduncle
- Middle cerebellar peduncle
Draw the cerebellar tracts (posterior, cuneo and ventral)
ok
What information does the posterior spinocerebellar tract carry?
Touch, proprioception and pressure sensation from lower limb
What information does the cuneocerebellar tract carry?
Touch, proprioception and pressure sensation from upper limb
Significance of the superior cerebellar peduncle
Efferents descending from the globose emboliform and dentate nuclei, as well as afferents from the ventral spinocerebellar tracts pass thorough here
Significance of the middle cerebellar peduncle
Afferents from pontine nuclei pass here to cortex
Significance of the inferior cerebellar peduncle
Afferents from spinal cord pass through here
General functions of the vestibulocerebellum:
Eye, neck and trunk movements
General functions of the spinocerebellum:
Axial and lower extremity movements, gait and station
General functions of the cerebrocerebellum
Precise, coordinated movements of the extremities (mainly upper)
Draw the efferent cerebellar tracts
Ok
What is the Inferior olivary nucleus tract important for?
Sends fibers back to the cerebellum. Important for correction of motor errors
Nature of cerebellar lesions.
Unilateral lesion affects the ipsilateral side
Ataxia:
Specific to the cerebellum (problem with afferents and efferents)
Voluntary jerky, inaccurate movements, wide based gait
Lesions of the vestibulocerebellum
Disrupts the integration of the vestibular system and flocculonodular lobe.
Nystagmus (beating of the eyes), truncal ataxia and truncal instability
Truncal ataxia
Truncal instability
can’t maintain sitting or balance. wide spaced gait
Cannot stand still/rocking, can’t tandem walk
Spinocerebellum lesions
Disrupts the connections between the cutaneous and proprioceptive tracts from the spinal cord to vermis region
Wide base gait and truncal ataxia
Damage to vestibulocerebellum and spinocerebullum generally result in…
Midline ataxia
Midline ataxia
Caused by vestibulo and spinocerebellar disease
Truncal instability. Tremor of trunk (titubation) and gait ataxia
Lesions of the cerebrocerebellum
Dysarthria: slurred speech (difficulty articulating)
Gait ataxia - tend to fall toward side of lesion
Limb ataxia due to cerebrocerebellar damage:
Dysdiadochokinesia
Dysmetria
Action tremor
- cannot rapidly alternate movements
- cannot move an intended distance
- shaking of limb during voluntary movement
Appendicular ataxia
Cerebellar hemisphere dysfunction Scanning dysarthria (speech ataxia), hypotonia, dysmetria, dysdiadochokinesia, decomposition of movement
Cerebellar ataxia
Positive romberg test - Unable to stand with feet together (with or without eyes open)
Normal vibratory, proprioception and ankle reflex
Sensory ataxia:
Positive Romberg test - Can stand with feet together and eyes open, but not when closed.
Abnormal vibratory, proprioception and ankle reflex
How would you test vestibulo or spinocerebellum dysfunction?
Test station, walking and tandem gait
How would you test cerebrocerebellum dysfunction?
Test rapid alternating movements, finger to nose/toe to finger/heel to shin, rebound and check reflex, speech
