Lecture 9 Flashcards
functions of cerebellum
maintain balance
maintain muscle tone/posture
coordinated movements (corrective feedforward/backwards roles)
motor learning/cognitive-motor role
DOES NOT initiate motor commands
cerebellum pathway of motor planning/learning
anterior association area -> premotor cortices -> pons -> cerebellum -> thalamus -> premotor/primary motor cortices
equilibrium
ability to maintain balance
vestibular nuclei in brainstem play primary central role
cerebellum location
posterior fossa of skull
attached to brainstem by cerebellar peduncles
forms the roof of fourth ventricle
brainstem structures
midbrain
pons
medulla
tentorium cerebelli
dural “roof” that separates cerebellum and occipital lobe
fourth ventricle
CSF cavity located posterior to pons
cerebral aqueduct
CSF pathway/conduit that connects the third and fourth ventricles
vermis
midline region of cerebellum
cerebellar hemispheres
intermediate hemispheres (paravermis) = medial portion of hemispheres
lateral hemispheres = large outer portion of hemispheres
flocculondular lobe
horizontal lobe located in the anterior region of cerebellum
oldest part of the cerebellum
can only be seen in the anterior view
cerebellar peduncles
three bundles of white matter that contain incoming and outgoing axons which transmit information to and from the cerebellum
*cerebellar peduncles physically connect the cerebellum to the brainstem
deep cerebellar nuclei
three pairs of nuclei located within the cerebellum
fastgial nuclei
interposed nuceli
dentate nuclei
fastigial nuclei
associated with vermis pathways
most midline
interposed nuclei
associated with paravermis pathways
two nuclei form interposed nuclei = emboliform nuclei, globose nuclei
dentate nuclei
associated with lateral hemispheres pathways
most lateral
arteries of the cerebellum
posterior inferior cerebellar artery (PICA)
anterior inferior cerebellar artery (AICA)
superior cerebellar artery (SCA)
flocculonodular lobe function
balance and vestibulo-ocular control
coordinated eye movement = smooth pursuit, saccades
vermis function
trunk and proximal limb coordination
paravermis (intermediate hemisphere) function
distal limb coordination/fine motor movement
lateral hemisphere function
coordination of motor planning for complex movement/learning
flocculonodular lobe pathway
input = vestibular nerve (CN 8) and vestibular nuclei
deep cerebellar nuclei = none
output = vestibular nuclei in brainstem to control eye movements and balance/equilibrium
vermis pathway
input = spinocerebellar tracts (unconscious proprioception) from trunk/proximal limbs, vestibular nuclei and visual information
deep cerebellar nuclei = fastigal nuclei
output = medial motor tracts in the spinal cord for trunk/proximal muscles
paravermis pathway
input = spinocerebellar tracts (unconscious proprioception) from limbs, motor cortex via pontine nuclei
deep cerebellar nuclei = interposed nuclei
output = red nucleus via rubrospinal tract, send fibers to thalamus and motor cortex via lateral motor tracts of spinal cord that control distal limb movement
lateral hemispheres pathway
input = motor association cortex via pontine nuclei
deep cerebellar nuclei = dentate nuclei
output = thalamus/cortex - information allows planning/learning complex movement in motor and somatosensory cortices, red nucleus - influences lateral motor tracts to assist in motor learning
pathological gaits associated with neurological conditions
cerebellar ataxic gait = wide BOS, arms out
hemiplegic gait = circumduction
spastic diplegic = CP
neuropathic gait = neuropathy foot drop
parkinsonian gait = shuffling, bradykinesia
choreiform gait = dancelike movement
cerebellar gait
standing posture = may see postural sway, wide base of support
ataxic gait = clumsy movement w/ wide BOS, arms out to maintain balance, difficulty walking in straight line or in tandem, veering to one side, uncoordinated movement of LE and UE
cerebellar lesions
DO impair motor activity
DO NOT result in motor paralysis
DO NOT impair ability to consciously detect sensory input
localization of lesions = not as precise as the cortex and proves challenging
unilateral = functional motor loss with be ipsilateral
bilateral = bilateral functional motor loss
hypotonia
reduced/decreased muscle tone
flappy, rag-doll, loose appearance, pt looks drunk
clinical exam procedures = observation, passive ROM, pendular deep tendon reflexes
disequilibrium
loss of balance
clinical exam procedures = standing balance tests, observation of gait, tandem walking, objective outcome measures
dyssyngeria
loss of coordinated movement activity
dysarthria
dystaxia
dysmetria
tremor - intention tremor
dysdiadochokinesia
nystagmus
decomposition of movement
rebound (aka overshooting)
dysarthria
uncoordinated speech, difficulty articulating, slurring
clinical exam procedures = observation (listening) of speech
dystaxia
ataxia, lack of coordination in the execution of learned voluntary movement
clinical findings = observation of trunk stability in sitting, standing posture, gait, ADL
dysmetria
overshooting, inability to stop muscular movement at a desired point in space
clinical exam = finger to nose test, heel to shin test, point-to-point (finger to finger) test
intention tremor
tremor that occurs with precise voluntary movement, oscillations occur/increase as patient approaches target
clinical exam = observe patient perform a precision task, observe during the finger to nose, heel to shin
dysdiadochokinesia
inability to perform rapid alternating or repetitive movement, disruption of the timing of the movement
clinical exam = ask patient to perform rapid alternating movement, rapid supination/pronation, rapid flat hand tapping
nystagmus
ocular dysmetria or spontaneous eye movement, rhythmic oscillation of the eyeballs
clinical exam = observe patient’s eyes when looking at extremes or moving in certain directions
dyssynergia
decomposition of movement = breaking down of smooth muscle activity into jerky, awkward fragments, poor timing
clinical exam = observe patient performing specific activity, patient’s movement is fragmented in individual steps
rebound
innaccurate return extremity to start position after forceful resistance
clinical exam = arm pull/extended test
