lecture 30 - motor systems: cerebellum Flashcards Preview

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Flashcards in lecture 30 - motor systems: cerebellum Deck (38)
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1
Q

what is truncal/gait ataxia?

A
  • wide-based, unsteady, “drunken sailor” gait

- difficulty standing, sitting

2
Q

what is appendicular ataxia?

A
  • dysmetria (improper measuring of distance in muscular acts)
  • intention tremor
  • dysdiqdochokinesia (difficulty preforming rapid, alternating movements)
3
Q

what is an intention tremor?

A

involuntary, rhythmic muscle contractions that occur during a purposeful, voluntary movement

4
Q

discuss the gross anatomy of the cerebellum

A
  • 3 lobes: anterior, posterior and flocculonodular
  • 2 fissures: primary and posterolateral
  • individual gyrus are called folia
  • 2 intermediate and 2 lateral lateral parts (divided by posterolateral fissure) of the 2 cerebellar hemispheres
  • vermis
  • superior, middle, inferior cerebellar preduncles
5
Q

describe the flocculonodular lobe of the cerebellum

A

-located at the ant. most portion of posterior lobe
(above posterolateral fissure)
-composed of nodulus & flocculus

6
Q

describe the vermis

A

the unpaired, median portion of the cerebellum that connects the two hemispheres

7
Q

what are the deep cerebellar nuclei? (from lateral to medial)

A
  • dentate
  • emboliform
  • globose
  • fastigial
8
Q

what is the interpositus nucleus?

A

some humans don’t have distinct emboliform and globose nuclie, they instead have one fused interpositus nucleus

9
Q

describe the basic cerebellar circut

A
  • cerebellar inputs from the climbing and mossy fibres act on the cortex as well as the deep cerebellar and vestibular nuclei, which send the cerebellar outputs
  • the cerebral cortex also has downstream inhibitory affects on the deep cerebllar/vestibular nuclei
10
Q

describe the cerebellar climbinf fibres in more detail

where do they come from and what is their role

A
  • they origionate from the inferior olivary nucleus

- the help train cerebellar circuit during motor learning

11
Q

what are the cortical layers of the cerebellum from superficial to deep?

A
  • molecular
  • purkinje cell (output)
  • granule cell
  • white matter
12
Q

what is unique to the granule cells in the cerebellum

A
  • they give rise to specialized axons called “parallel fibers” that ascend to the molecular layer of the cerebellar cortex that relay information to the purkinje cells
  • i.e., they’re also involved in input
13
Q

what are the functions of the cerebrocerebellum?

A

motor planning and selection

14
Q

which specific areas of the cerebellum are involved in motor planning and selection?

A

lateral part of the hemispheres

15
Q

describe the motor planning and selection pathway

A

motor areas of the cerebral cortex –> pontine nuclei –> climbing/mossy fibres –> cerebellar cortex/dentate nucleus –> ventrolateral thalamus –> motor areas of the cortex/red nucleus

16
Q

what are the functions of the spinocerebellum?

A

sensory feedback control and motor coordination

17
Q

whic specific areas of the cerebellum are involved in sensory feedback control and motor coordination?

A
  • intermediate part of the hemispheres (limbs)

- vermis (axial)

18
Q

describe the sensory feedback control and motor coordination pathway

A

somatosensory afferents, sc, motor cortex –> climbing/mossy fibres –> cortex/ interpositus nuclei (int part)/fastigial nuclei (vermis) –> motor cortex/red nucleus (int part)/motor cortex/vestibular nuclei/reticular formation (vermis)

19
Q

describe the pathway for spinal feedback from the lower limb

A
  • via ventral spinocerebellar tract:

- ventral commissure –> superior cerebellar peduncle

20
Q

describe the pathway for afferent feedback from the lower limb

A
  • via dorsal spinocerebellar tract:

- proprioceptive and cutaneous afferents –> clarke’s column –> inferior cerebellar peduncle

21
Q

describe the pathway for spinal feedback from the upper limb

A
  • via rostral spinocerebellar tract: little known about this pathway
  • enters through inferior and superior peduncles
22
Q

describe the pathway for afferent feedback from the upper limb

A
  • via cuneocerebellar tract:
  • proprioceptive and cutaneous afferents –> fasciculus cuneatus –> external cuneate nucleus –> inferior cerebellar peduncle
23
Q

describe the location of leg, arm, head and auditory/visual information in the vermis/the intermediate hemispheres from anterior to posterior

A
  • ant. lobe: leg, arm, head
  • stem of vermis: auditory/visual info
  • post: head, arm, leg
24
Q

which tract is associated with the arms?

A

rostral spinocerebellar

25
Q

which tract is associated with the legs?

A

ventral spinocerebellar

26
Q

which peripheral afferents tract is associated with the arms?

A

cuneocerebellar

27
Q

which peripheral afferents tract is associated with the legs?

A

dorsal spinocerebellar

28
Q

what are the functions of the vestibulocerebellum?

A
  • control, balance and equilibrium
  • vestibulo-ocular reflex
  • smooth pursuit eye movements
29
Q

what is the vestibulo-ocular reflex?

A

a gaze stabilizing reflex: ensures stable vision

30
Q

which areas of the cerebellum are involved in the vestibulocerebellar functions?

A

flocculonodular lobe

31
Q

describe the vestibulocerebellar pathway

A

vestibular apparatus –> climbing/mossy fibres –> cortex/vestibular nuceli –> vestibulospinal tract, medial longitudinal fasciculus

32
Q

the main cerebellar input/output pathways are related to the:

A

cerebellar peduncles

33
Q

describe the superior cerebellar peduncle pathway

A
  • input: sc (ventral and rostral spinocerebellar)

- output: thalamus, red nucleus, tectum

34
Q

describe the middle cerebellar peduncle pathway

A

input: pontine nuclei

35
Q

describe the inferior cerebellar peduncle pathway

A
  • input: vestibular nuclei, sc (dorsal and rostral spinocerebllar and cuneocerebellar), clinbing fibre from inferior olive
  • output: vestibular nuceli, reticualr formation, medial longitudinal fasciculus
36
Q

which vessels supply the cerebellum?

A
  • superior cerebellar artery (top)
  • AICA (outside point on ant., middle on post.)
  • PICA (bottom, bit of vermis)
37
Q

what can occur as a result of cerebellar lesions

A
  • ataxia (covered above)
  • eye movement abnormalities
  • speech difficulties (irregular rate/volume, slurred)
38
Q

list possible eye movement abnormalities w respect to cerebellar lesions

A
  • ocular dysmetria (involves the constant under- or over-shooting of the eyes when attempting to focus gaze on somethin)
  • nystagmus (involuntary rhythmic side-to-side, up and down or circular motion of the eyes)
  • impaired vestibulo-ocular reflex