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NUERO-ANATOMY > 2-4 sensorimotor system > Flashcards

2-4 sensorimotor system Flashcards

1
Q

what type of arrangement does the sensorimotor system have

A

somatotopic

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2
Q

sensory info is processed by what 2 main pathways

A

pain & temp

touch & position

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3
Q

motor info is mediated by what 2 main pathways

A

corticospinal tracts go to the body

corticobulbar tracts go to the head & neck

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4
Q

what is the final common pathway to the muscle

A

the lower motorneuron

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5
Q

the cranial nerves control muscles that are important for what

A

voice & speech

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6
Q

where do motorneurons have their nuclei

A

anterior horn

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7
Q

where do sensory neurons have their nuclei

A

posterior horn

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8
Q

dorsal root ganglion

A

before the dorsal root fibers join the spinal column

contains sensory nerve bodies

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9
Q

dorsal root

A

consists of the fibers that transmit impulses to the CNS

afferent

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10
Q

dorsal columns pathway

A

come into spinal cord on ipsilateral side & travels up to medulla

2nd order neuron cross in medulla then onto thalamus
- becomes medial lemniscus

thalamus projects to primary sensory areas

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11
Q

dorsal columns sensory info

A

ascending tracts w/ info about touch & limb position

lesions cause ipsilateral damage

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12
Q

spinothalamic tract pathway

A

immediately crosses over at spinal cord

2nd axon travels to thalamus

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13
Q

spinothalamic tract sensory info

A

carries pain & temp info

lession will causes contralateral pain & temp deficits

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14
Q

innervation ratio

A

the number of fibers controlled by 1 neuron

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15
Q

low innervation ratio =

A

very fine motion

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16
Q

large innervation ratio =

A

large force & motion

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17
Q

how is a muscle action potential generated

A

acetylcholine opens gates allowing Ca2+ ions in

this release causes small filaments within muscle fiber to shorten – muscle contraction

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18
Q

myasthenia gravis

A

chronic autoimmune disorder

weakness of skeletal muscles

reduced efficiency in muscle contraction, they cannot contract repeatedly

eye fatigue

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19
Q

MG cause

A

dysfunction at the neuromuscular junction

decrease in the ability of Ach to act as a neurotransmitter

receptor sites for Ach do not function

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20
Q

reflex

A

involuntary - in response to sensory stimulation

simple stretch reflex - sensory neuron –> motor neuron

pain reflex - pain neuron –> interneuron –> motor neuron

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21
Q

central pattern generator

A

network of neurons capable of carrying out patterned motor response

more complex than a reflex

voluntary but don’t really have to think about it

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22
Q

volitional movement

A

organized around the performance of a purposeful task

improves w/ experience/practice

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23
Q

lower motor neuron

A

lesion at a brainstem spinal motor nucleus or in the nerves leading out to the muscles

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24
Q

composition of LMN

A

cell body - brainstem or spinal cord

axon

motor end plate - synapse onto muscle

controls ipsilateral muscles

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25
LMN integration
peripheral sensory system - reflexes, ongoing modulation direct activation system - UMN / cortical system activates LMN, volitional movement indirect activation system - extrapyramidal influences LMN
26
damage to LMN
weakness paralysis if muscles if deprives of all input hyporeflexia - reflexes are diminished atrophy fasiculation - spontaneous motor unit discharges that can be seen as twitches fibrillation - muscles contract regularly, can't be seen through skin
27
upper motor neuron
neurons that form the descending motor pathways from the brain to the spinal cord or brainstem corticobulbar & corticospinal fibers (pyramidal tracts)
28
effects of damage from UMN
weakness (spastic -- tight & stiff) increased background muscle activity -- additional firing lack of muscle control hyper-reflexia
29
corticobulbar tract
fibers originate from the cerebral cortex & descend fibers branch off at the medulla, pons, & midbrain cross over at the brainstem at the level of thee CN nuclei they innervate most bilateral, some unilateral
30
direct activation pathways
UMN inervates LMN bilaterally or contralaterally
31
pyramidal tract
direct originated form primary motor area & descends through internal capsule cortiobulbar or corticospinal tracts
32
damage to direct activation pathways
loss or reduction of skilled movements
33
indirect pathways
descending projections from cortex (BG) to gamma motor neurons reticular formation of pons & medulla that project to spinal cord (reticulospinal tract)
34
gamma motorneurons
set the background muscle activity & excitability
35
indirect pathways functions
reflexes posture background muscle activity skilled, discrete actions
36
extrapyramidal system
complex functions for speech & swallowing UMN influenced by BG, cerebellum, sensory cortical areas, vestibular nuceli
37
tectospinal tract
extrapyramidal regulates neck & body twisting movements w/ support from visual & auditory startle reflexes
38
rubrospinal tract
regulates muscle tone for limb extension to support body against gravity
39
vestibulospinal tract
regulates reflexive adjustment of the body & limbs to keep the head stable
40
how does primary motor cortex contribute to movement
motor commands for execution of movement only cortical area w/ a direct projection to corticospinal tract
41
how does premotor cortecx contribute to movement
plans skilled movements w/ external targets projects to primary motor cortex & extrapyramidal brainstem
42
how does supplemental motor cortex contribute to movement
plans sequences of actions
43
basal ganglia functions
regulates background muscle activity supports goal directed movements postural adjustments during skilled movements learning new movements initiates movements
44
BG input
cortical from areas involved in planning & execution of movements
45
BG output
via thalamus to the motor cortical areas
46
BG controls
contralateral
47
BG input structures
striatum caudate putamen
48
BG output structures
globus pallidus internal & external segment substantial nigra
49
other BG structures
substania nigra pars compacta (dopamine) pars reticula subthalamic nucleus nucleus accumbens
50
neurotransmitters in BG
dopamine -- modulatory acetylcholine -- high concentrations glutamate (excitatory) GABA (inhibitoty)
51
Parkinson's Disease
rigidity initiation difficulties slowness olfaction, cognition, autonomic, mood, sleep
52
Parkinson's treatments
drugs - levodopa, dopamine behavioral - exercise surgical - ablation, transplantation, deep brain stimulation
53
how is huntington's inherited
autosomal dominant genetic disorder typically develops around 35-45 yrs
54
huntington's symptoms
chorea, jerky & involuntary movements cognitive deficits psychiatric disorders
55
huntington's treatment
tetrabenzine (VMAT inhibitor) & other drugs functional therapy
56
function of cerebellum
process info from all parts of the brain to produce coordinated, smooth movement balance hand-eye coordination IPSILATERAL
57
cerebellum input
from sensory systems & sensorimotor systems like cortex & BG
58
cerebellum output
to the brainstem, extrapyramidal system, & cerebral motor cortices
59
4 main pathways of cerebellum
cerebrocerebellar spinocerebellar vestibuloscerebellar pontocerebellar
60

NUERO-ANATOMY (9 decks)

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