spinocerebellum Flashcards
What is the major role of the spinocerebellum?
being a comparator
Comparator: The spinocerebellum first receives information about what movement?
intended movement (often called an efference copy)- copy of the outgoing command to move
what can we think of the efference copy as?
feed forward signal via the cerebro-olivary and olivocerebellar inputs.
What feedback signals does the spinocerebellum receive?
input from the patterns of peripheral proprioceptor discharge
How does the cerebellum constantly update movement?
by comparing the efferent copy command with the feedback of what has happened
What are the functions of the vermis?
- movement coordination of axial and proximal limb musculature
- regulating postural muscle tone
What inputs are there to the vermis?
-proprioception
-vision
-vestibular
sensory systems
Damage to the spinal proprioceptive pathways results in what?
sensory ataxia
what are symptoms of sensory ataxia?
- ataxic symptoms without visual support (near normal coordination when visually observed by pt)
- increase in postural sway
- difficulty in standing with narrow base of support particularly with eyes closed (Romberg sign)
- uncoordinated gait
How is the cerebellum somatotopically mapped?
separate maps on anterior and posterior lobes of the cerebellum
the two homunculi are inverted images of one another
cerebellum homunculi. neck and trunk are where? extremeties are where?
neck and trunk are distributed along the vermis while extremities are aligned along the paravermal cerebellar cortex
What are the 5 afferent tracts that provide proprioceptive information into the spinocerebellum?
- dorsal spinocerebellar tract
- cuneocerebellar tract
- ventral spinocerebellar tract
- rostral spinocerebellar tract
- trigeminocerebellar projections
Where does the dorsal spinocerebellar tract (DSCT) arise from?
cells of nucleus dorsalis (clark’s) in spinal segments T1 to L2 or 3
afferents from DSCT are primarily from what type of receptor?
muscle and joint receptors (maybe some cutaneuous)
DSCT axons rise in which way in what structure to enter the cerebellum in what structure?
rise ipsilaterally in the dorsal lateral funiculus to enter the inferior cerebellar peduncle
DSCT axons end where?
in areas representing LE and trunk in anterior and posterior lobes
ventral spinocerebellar tract (VSCT) arises from where?
nuclei scattered in the base of the dorsal horn
how do VSCT axons rise? in what structure?
decussate to rise in peripheral lateral funiculus just ventral to the CL DSCT
When the VSCT axons ascend through the medulla and pons what happens?
to decussate again and enter the cerebellum through the superior cerebellar peduncle
where do VSCT axons end?
in the trunk and LE representation of anterior lobe and paramedian lobule
What activity do both VSCT and DSCT have in common?
they both have phasic activity during gait stepping cycle but sectioning dorsal roots affects only the DSCT
Even with dorsal roots being cut, which tract still continues the phasic gait cycle?
VSCT because these cells at the base of the dorsal horn are driven by descending motor commands (efferent copy)
With dorsal roots cut, which tract loses phasic gait cycle pattern?
DSCT because the neurons of the clarkes column are driven by proprioceptive afferents- unconscious proprioception
What primary afferents in the cuneocerebellar tract (CCT) composed of?
primary afferents from the upper extremity proprioceptors
in what structure do the primary afferents of the CCT ascend?
fasciculus cuneatus
where do primary afferents of CCT end?
in accessory (lateral) cuneate nucleus (ACN)
where is the accessory cuneate nucleus located?
caudal medulla
CCT axons from the ACN enter the cerebellum through what structure?
the inferior cerebellar peduncle
What does the CCT axons innervate?
areas representing UE of both anterior and posterior lobe paravermal areas.
CCT also probably represents afferents from what body part as well?
cervical spine
CCT relaying in the ACN only carry information from what structures?
muscle spindles
GTOs
joint receptors
Where does cutaneous input enter the cerebellum?
from neurons in the MAIN cuneate nucleus (providing proprioceptive input from the hands and fingers)
How do axons of the rostral spinocerebellar tract (RSCT) arise? from?
- from cells scattered in the base of the dorsal horn through cervical segments
- ipsilaterally to enter through the inferior cerebellar peduncle
there is evidence that says that the RSCT also can arise in what way?
contralaterally to enter the cerebellum through the superior cerebellar peduncles (running with the VSCT)
where do RSCT axons end?
both LE and UE representations of ipsilateral anterior and posterior lobes of the cerebellum
Where does the trigeminocerebellar tract (TCT)arise from?
cells in the mesencephalic, chief sensory, and spinal tract nuclei of CN V
Where do TCT fibers enter through?
some through superior and others through inferior cerebellar peduncle
how do TCT axons end?
ipsilaterally in the posterior lobe area where face representation is seen
What are two other inputs into the spinocerebellum?
visual and auditory
where do visual and auditory inputs end?
in the same region as face representation in the posterior lobe
what do visual inputs into the cerebellum provide?
sense of vertically and horizontally from the visual space for maintenance of upright stance
What are some things that the cerebellum does in the role of cognitive function related to hearing?
- speech generation
- auditory processing
- auditory memory
- abstract reasoning & solution of problems
- sensorial discrimination and information processing
- language processing and linguistic operations
What do fastigial nucleus outputs include?
vermal outputs to vestibular and reticular nuclei
fastigial nucleus outputs project in which way to control what?
bilaterally to control axial muscles
where else do vermal outputs project?
to ventral lateral nucleus of the thalamus
Fastigial outputs from spinocerebellum function in control of what?
proximal musculature during movement as in providing proximal stability for distal mobility
globose and emboliform nuclei axons exit then what?
decussate in the superior cerebellar peduncle as cerebellorubral fibers
where do cerebellorubral fibers terminate?
in the magnocellular part of the red nucleus (these outputs appear to activate the rubrospinal pathways)
Cerebellothalamic fibers come from which axons?
globose and emboliform nuclei axons
where do cerebellothalamic fibers end?
in the VL nucleus of the thalamus (which then goes to the motor cortex)
Which nuclei is it suggested that are involved in fine motor control of the UE?
globose and emboliform pathways to both the red nucleus and the thalamus to motor cortex
Damage to globose and emboliform produces what/
3-5 Hz intention tremor during reaching tasks (but no similar effect of damage on gait or standing balance)
