5290 - Neuro > Motor System > Flashcards

Motor System Flashcards

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1
Q

parts of the motor system

A

Motor Cortex, Brainstem, Spinal Cord, Motor Nerves (CN & spinal), Basal Ganglia, Cerebellum

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2
Q

parts of the motor system that input to the motor cortex

A

basal ganglia (force) and cerebellum
(accuracy)

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3
Q

flow of info for motor functions

A

posterior cortex sends sensory information to frontal cortex (sends goals) -> prefrontal cortex plans movements -> premotor cortex organizes movement sequences -> motor cortex executes actions

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4
Q

how many homunculi in the primary motor and premotor cortices

A

as many as 10

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5
Q

disproportionate sizes of body parts in homunculi

A

correspond to complexity of movements that they can perform
- larger area on homunculi = greater motor control

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6
Q

areas on homunculi that are larger

A

hand and face

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7
Q

can the relative size of homunculus sizes change

A

yes, motor learning can change it (neuroplasticity)
- ex: learning an instrument like piano can create a larger area for fingers and hands

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8
Q

motor cortex is specialized for

A

control of muscle combinations (movements) rather than control of individual muscles

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9
Q

different homunculi represent

A

different classes of movement specified by body part, movement location & function
- ex: reaching/grasping, gait, speech. chewing

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10
Q

2 main motor pathways

A

Direct (Pyramidal) Pathway
Indirect (Extrapyramidal) Pathway

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11
Q

DP: pyramidal neurons (upper motor neurons) originating in motor cortex project directly to

A
  • brainstem as corticobulbar tract
  • spinal cord as corticospinal tract (aka pyramidal tract)
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12
Q

upper motor neurons are in

A

CNS

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13
Q

lower motor neurons are in

A

PNS (spinal nerves or motor cranial
nerves)

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14
Q

corticobulber tract project from

A

motor cortex to brainstem

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15
Q

corticobulbar tract synapses on

A

cranial nerves (lower motor neurons) that control muscles of face, head, and neck (CN 5, 7, 9, 10, 11, 12)

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16
Q

corticobulbar regulation of most motor neurons is

A

bilateral

(fibers from motor cranial nerve X innervate left and right cranial nerve motor nuclei in the brainstem)

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17
Q

implication of bilateral innervation

A

Unilateral lesions to upper motor neurons have mild effects on motor control of speech, but bilateral lesions can cause severe dysarthria

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18
Q

corticospinal tract projects from

A

projects from primary motor cortex to spinal cord

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19
Q

95% of fibers from each hemisphere in corticospinal tract ……;
descend as what tract

A

cross in brainstem (at the pyramidal
decussation) and descend in the spinal cord as the lateral corticospinal tract

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20
Q

lateral corticospinal tract controls

A

movements of limbs/digits

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21
Q

(corticospinal tract) 5% of fibres from each hemisphere:
what does it control

A

do not cross in brainstem and descend
in the spinal cord as the ventral (or anterior) corticospinal tract
(is mostly ipsilateral);

movements of trunk

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22
Q

Ventral corticospinal tract controls

A

movements of trunk

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23
Q

Corticospinal axons terminate on

A

spinal cord motor nerves (lower motor neurons)

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24
Q

corticospinal tract axons in spinal cord;
arrangemened as a __________

A
  • Located in the ventrolateral spinal cord and jut out to form the ventral horns
    – Arranged as a homunculus
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25
in spinal cord, interneurons project to _______ Motor neurons project to ________
motor neurons; muscles of the body
26
is corticospinal tract mostly crossed or uncrossed
mostly crossed
27
unilateral lesions to upper motor neurons affect with corticospinal tract
affect limb movement on the opposite side of the body - hemiplegia - hemiparesis
28
hemiplegia; damage to which tract
paralysis on one side (wheelchair); corticospinal
29
hemiparesis; damage to which tract
weakness on one side (walker) corticospinal
30
names of the corticospinal/bulbar axons while in the cortex
Corona radiata
31
names of the corticospinal/bulbar axons at the level of the basal ganglia
internal capsule
32
names of the corticospinal/bulbar axons at the level of the midbrain
Cerebral peduncles
33
names of the corticospinal/bulbar axons at the level of the medulla
pyramidal tract
34
cerebellum and basal ganglia
modulate and control
35
all motor senses go through corticobulbar except
eye movement system
36
2 main direct pathways
corticobulbar and corticospinal tracts
37
why are most cranial nerves bilaterally innervated
redundancy incase of damage
38
corona radiata, internal capsule, cerebral peduncles, and pyramidal tract all the _____ axon
same, just the different names for the different parts
39
what is the bouquet analogy
about the corticobulbar/spinal axons, petals - axons high up (corona radiata) stems - internal capsule (come together)
40
where would a lesion along the corticospinal/bulbar axon have the most detrimental affect
at the internal capsule because this is where they have all come together and its the highest up
41
where is the large crossing in the corticospinal/bulbar axons
at the decussation of pyramids
42
two main parts of indirect pathway
basal ganglia and cerebellum
43
what does the indirect pathway do
its not actually executing movement, its providing signals for movements to be appropriate (influences the direct pathways)
44
if the input isn't getting to the basal ganglia you get
the opposite of Huntington's disease
45
circuitry for indirect pathway in the basal ganglia
- Reciprocal connections to cortex * Reciprocal connections to substantia nigra * Projections to thalamus (motor nuclei) * Output to brainstem & spinal cord * Modulates activity in direct pathway
46
are there excitatory or inhibitory pathways in basal ganglia for IDP
both
47
inhibition synapse on inhibition =
disinhibition
48
what is the saying for basal ganglia and what it compares to
a volume dial for movements
49
what does the basal ganglia function in
controlling and coordinating movement patterns for large groups of muscles
50
damage to basal ganglia can result in
hypokinetic symptoms (e.g., Parkinson’s disease) hyperkinetic symptoms (e.g., Huntington’s disease)
51
cerebellum connections
somatosensory inputs from spinal cord (spinocerebellar pathways) vestibular inputs from brain stem & CN8 Multiple paths to/from cortex
52
cerebellum output
to cortex, and Provides output (indirectly) to spinal motor neurons
53
cerebellum involved in
Involved in movement coordination (i.e., timing, accuracy), motor learning, balance
54
what does the cerebellum look at
what movement you actually did and what you intended to do
55
what activities is the cerebellum involved in
activities that you get better at w practice
56
damage to cerebellum can result in
an intention tremor (not resting like in parkinsons, this one only happens when you go to move, not when you're still)
57
cerebellum: feedback circuits allow
cerebellum to adjust movements to match intentions (ex. throwing dart)
58
cerebellum contains about ____ of all neurons in the entire nervous system (gathered in folia)
half
59
where are the neurons gathered in the cerebellum
in the folia
60
cerebellum is divided....
into two hemispheres with multiple lobes
61
flocculus project from the _______ surface of the cerebellum; involved in
project from the ventral surface of the cerebellum involved in eye movements, balance
62
vermis ......
protrudes along dorsal midline of cerebellum (termination site of spinocerebellar pathways)
63
the cerebellum has a ___________ organization
homuncular organization
64
folia are the
bumps
65
medial part of cerebellar hemispheres encode
movement of body midline
66
lateral parts of cerebellar hemisphere encode
movement of body appendages
67
are involved in acquiring and maintaining motor skills
cerebellum
68
cerebellum is __________ organized
topographically
69
damage in cerebellum can result in
ataxia - reduced fine motor control - intention tremor etc.
70
slide 35
71
which pathway stops in the brainstem; which pathway goes down to the spinal cord
corticobulbar tract; corticospinal tract
72
lower motor nerves info (4 things)
1 - PNS 2 - originate in brainstem as cranial nerves 3 - originate in spinal cord as spinal nerves 4 - terminate at muscles
73
info about upper motor neurons
1 - CNS 2 - Originate in cortex and terminate in brain stem (corticobulbar tract) or spinal cord (corticospinal tract) 3 - Pyramidal system (CB & CS tracts) directly controls LMN’s 4 - Extrapyramidal system influences pyramidal system & therefore indirectly controls LMN’s
74
which system controls lower motor neurons
Pyramidal system (CB & CS tracts) directly controls LMN’s
75
which system influences pyramidal system, indirectly controls lower motor neurons
Extrapyramidal system
76
which cranial nerves does the corticobulbar tract synapse on
CN 5, 7, 9, 10, 11, 12 control muscles of face, head, and neck
77
What’s the main difference between upper and lower motor neurons?
upper: never leave the CNS (brain and spinal cord) lower: Leave the CNS to connect directly to muscles in the PNS.
78
Where do upper motor neurons start and end?
Start: Motor cortex (brain) End: Brainstem or spinal cord (where they synapse with LMNs)
79
Where do lower motor neurons start and end?
Start: Brainstem (cranial nerves) or spinal cord (spinal nerves) End: Muscles (they cause contraction)
80
What is the function of upper motor neurons?
Send movement commands from the brain to the spinal cord or brainstem.
81
What is the function of lower motor neurons?
Carry signals from the spinal cord/brainstem to the muscles — make movement happen.
82
corticobulbar controls muscles of
head, neck, and face (except eye movements)
83
corticospinal controls muscles of
the other body muscles
84
corticobulbar is __lateral
bilateral (redundancy)
85
corticospinal is __lateral
contralateral
86
bilateral lesions of upper motor neurons can cause
severe dysarthia
5290 - Neuro
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