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
