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Neuroscience > Exam II > Flashcards

Exam II Flashcards

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1
Q

Pyramidal system

A

Drive voluntary movements by activating ventral horn lower motor neurons directly, UMN pathways

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2
Q

Extrapyramidal system

A

Modulate voluntary movements by regulating the motor neurons indirectly, not part of the UMN pathways, tracts outside of the pyramids

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3
Q

Lateral MTs

A

innervate distal limb muscles for fine motor control and perform fractionated movements

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4
Q

Medial MTs

A

innervate axial/proximal girdle muscles to control posture and perform gross movements, involuntary coordinated responses that are mostly initiated in brainstem centers

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5
Q

Non-specific MTs

A

Do not activate or regulate any specific movements, activate during stress or emotions

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6
Q

Lateral corticospinal tracts

A

Most important tract controlling voluntary movements, unique ability to generate fractionated movements by using interneurons to inhibit unwanted neighboring muscles

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7
Q

Rubrospinal tracts

A

Arises in red nucleus in midbrain, decussates and descends to innervate contralateral motor neurons that activate wrist/finger extensors. In humans, it is small and makes minor contribution to control of distal upper limb muscles

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8
Q

Reticulospinal tracts

A

to regulate muscle activity in trunk and proximal limb muscles, help with gross movements needed during walking, help with automatic anticipatory postural adjustments during movements like reaching, carrying objects, control of autonomic functions

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9
Q

Medial vestibulospinal tract

A

Receives information about head position in space from vestibular nuclei, Regulates motor neurons bilaterally to control neck and upper back muscles (extensors)

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10
Q

Lateral vestibulospinal tract

A

Regulates motor neurons ipsilaterally to activate trunk paravertebrals and proximal LE extensors while inhibiting flexors to maintain upright antigravity posture within BOS

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11
Q

Medial/Anterior corticospinal tracts

A

activate neck, shoulder and trunk muscles, prepare the postural system for intended movements and coordinate posture with the other medial tracts

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12
Q

Nonspecific motor tracts

A

Facilitate all types of motor neurons across spinal cord, Activated during intense stress and emotions, involved in sending descending pain-regulating information

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13
Q

Corticobulbar (corticobrainstem) tracts

A

control of muscles in head, activate cranial motor nerve nuclei bilaterally that innervate muscles of face (except lower half muscles), mastication, tongue, pharynx, larynx, and some neck muscle (SCM/traps)

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14
Q

Cortical motor areas

A

Premotor and supplementary motor area plan for complex movements, in association with M1

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15
Q

Alpha (α MNs) motor neurons

A

large cell bodies, large myelinated axons – connect to extrafusal muscles

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16
Q

Gamma (γ MNs) motor neurons

A

medium cells bodies and myelinated axons – connect to intrafusal spindle muscle fibers

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17
Q

Synergy involving muscles at same joint

A

activate other muscles at same joints
Phasic synergy - modulated in both amplitude and timing
by Ia afferents
monosynaptic

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18
Q

Synergy involving muscles at neighboring joints

A

activate muscles at other neighboring joints
Tonic synergy - modulated only in amplitude
by II afferents
bisynaptic/polysynaptic

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19
Q

Hemiplegia or -paresis

A

(lesion of corticospinal tracts high up in the brain, may retain some voluntary control due to intact reticulospinal tracts) – stroke, TBI, CP

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20
Q

Quadriplegia or -paresis

A

(lesion of MTs in higher spinal levels) - SCI

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21
Q

Paraplegia or -paresis

A

(lesion of MTs in lower spinal levels) - SCI

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22
Q

Hypertonia

A

abnormal high resistance to passive stretch

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23
Q

Spasticity

A

velocity dependent – in UMN pyramidal/extrapyramidal MT lesions (stroke, SCI)

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24
Q

Rigidity

A

velocity-independent – in basal ganglia lesions (Parkinson’s disease)

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25
Babinski’s sign
due to lack of inhibitory control by corticospinal tracts on withdrawal reflex receptive fields, normal till 6 months age as corticospinal tracts not myelinated by then.
26
Signs of motor cortex/tract lesions (UMN lesions)
Paresis/paralysis Abnormally high tone Abnormally high reflex activity Loss of fractionated movements Abnormal synergies Myoplasticity Abnormal co-contractions – CP
27
Signs of motor neuron lesions (LMN lesions)
Paralysis or paresis - flaccidity Decrease in muscle tone – hypotonia/flaccidity Decrease or loss of reflexes (hyporeflexia) Neurogenic atrophy – due to lack of trophic support to muscles
28
Clonus
Involuntary reflexive repeating contractions of a single muscle group in response to quick stretch – a manifestation of hyper-reflexia
29
Cause of Clonus
lack of descending MT control, allowing activation of oscillating neural networks in spinal cord
30
Myoplasticity
Adaptive changes in muscles in response to changes in neuromuscular activity level, occurs due to increased number of weak actin-myosin bonds, contracture.
31
feedforward mechanism
Anticipatory use of sensory information
32
feedback mechanism
Use of sensory information during and after movement to make corrections/adjustments
33
Mechanoreceptors
Touch, pressure, stretch, vibration
34
Thermoreceptors
respond to heating/cooling
35
Chemoreceptors
respond to chemicals
36
Somatosensations from skin (cutaneous)
touch, temperature, nociception
37
Somatosensations from MSK system
proprioception, nocioception
38
Tonic receptors
Pressure receptors – therapeutic touch Stretch receptors in muscle
39
Phasic receptors
Tendon stretch receptors Pressure receptors Thermoreceptors
40
Nuclear bag fibers
more elastic – stretch quickly
41
Nuclear chain fibers
less elastic – stretch slowly
42
Ia muscle spindle
responds better to quickly-changing muscle length using ‘phasic’ discharge pattern – velocity-dependent discharge - dynamic sensitivity
43
II muscle spindle
responds better to slowly-changing muscle length using ‘tonic’ discharge pattern – not dependent on velocity of change in muscle length - static sensitivity
44
Gamma dynamic
activate bag fibers
45
Gamma static
activate both bag and chain fibers
46
Axons for DC/ML pathways
stay on same side of spinal cord and travel up to medulla
47
Axons for AL (ST/Divergent) pathways
enter the spinal cord and synapses with the 2nd order neuron right away (which crosses over)
48
Dorsal column/medial lemniscus sensations
Light touch, proprioception, vibration
49
Anterolateral columns (spinothalamic + divergent pathways)
Convey nociception/pain, temperature and crude touch information to brain
50
Spinothalamic pathway
fast, discriminative pain and temperature and crude touch, somatotopic arrangement in S1, 3 neuron pathways
51
Divergent pathways
slow, non-specific, crude nociception – no somatotopy, 2 or 3 neuron pathways, more associated with chronic pain
52
Primary somatosensory area (S1)
somatotopic arrangement of sensory information (touch, proprioception, nociception, temperature)
53
Secondary somatosensory area
further processing of S1 information by sending to association/cognitive areas to provide ‘perception’ to incoming sensory information
54
1st order neuron
C fibers, Synapse with interneurons in dorsal horn, Interneurons release substance P, Can get sensitized by repeated stimulation during chronic injury
55
2nd order ascending neurons
Spinoreticular, Spinomesencephalic, Spino-emotional
56
3rd order neurons (only for spino-emotional)
To wide areas in cortex – anterior cingulate, insula, amygdala, dorsal prefrontal cortex Affect emotions, behavior, personality
57
Unconscious Spinocerebellar pathways
Convey information needed to monitor and adjust movement coordination to cerebellum dorsal SC: stays ipsi ventral SC: crosses over twice
58
Fidelity
determine precision of location, intensity, timing
59
High-fidelity information
light touch, proprioception, sharp discriminative pain/temperature
60
Low fidelity information
aching pain, itch
61
Conscious relay pathways
light touch, proprioception, discriminative pain/temperature - high fidelity
62
Conscious divergent pathways
info conveyed to many higher locations – conscious and emotional levels - low fidelity – aching pain/chronic pain
63
Non-conscious pathways
proprioceptive info to cerebellum for postural control
64
Pre-embryonic timeline
conception to day 14
65
Embryonic timeline
Day 15 to end of wk 8
66
Fetal timeline
Start of 9th wk to birth
67
Pre-embryonic stage
Starts with repeated cell division, solid sphere, cavity opens, development of embryonic disc
68
Embryonic stage
all organs are formed
69
Ectoderm
epidermis, sensory organs, the Nervous System
70
Mesoderm
dermis, muscles, skeleton, excretory, circulatory systems
71
Endoderm
gut, liver, pancreas, respiratory system
72
Neural tube
primordium of the CNS (brain and spinal cord)
73
Neural crest
group of cells that break off of the tube, forms much of PNS (DRGs, sensory CNs, ANS, schwann cells, endocrine organs etc).
74
Hindbrain
medulla, pons, cerebellum, 4th ventricle
75
Midbrain
Midbrain
76
Forebrain
diencephalon and telencephalon
77
Telencephalon
cerebral hemispheres and basal ganglia
78
Diencephalon
thalamus, hypothalamus
79
Sensory loss may proceed in the following order of descending diameter
Sensory loss may proceed in the following order of descending diameter 1. Conscious proprioception/light touch 2. Cold 3. Fast nociception (sharp pain) 4. Heat 5. Slow nociception (aching pain, tingling, prickling sensations) During recovery, sensation returns in the reverse order
80
Referred pain mechanism
Occurs when branches of nociceptive fibers from internal organs (autonomic) and branches of nociceptive fibers from skin (somatosensory) converge on same 2nd order neuron in dorsal horn or thalamus, and those pathways become sensitized
81
Motor pools
cluster of motor neurons that connect to single muscle belly
82
Withdrawal reflex
Reflexive withdrawal from stimulus Elicited by painful cutaneous stimuli Needs synaptic interactions between neurons at various spinal cord levels
83
Crossed extension reflex
Reflexive extension of the other LE to support posture and prevent falling
84
Reciprocal inhibition
During agonist muscle contraction or reflex activity, inhibition of antagonist is achieved by activating inhibitory interneurons in spinal cord that inhibit motor neurons of the antagonist group.
85
Sensory nerve conduction velocity (NCV) studies
to test the integrity of peripheral nerves following injuries
86
Main factors that limits functional activities after stroke
paresis, loss of fractionated movement, hypertonia, abnormal synergies and myoplastic changes
87
Main factors that limit functional mobility after SCI
paresis/paralysis, stretch hyperreflexia and myoplastic changes – sometime hyperflexia can be useful for SCI patients
88
Light touch
via A beta afferents, skin pressure (light), vibration, skin stretch
89
Coarse touch
by free nerve endings via Aδ and C afferents Pleasant touch Pressure (firm/deep) Tickle/itch Nociception (pinch)
90
Spinoreticular
to reticular formation – arousal, attention changes due to pain
91
Spinomesencephalic
to superior colliculus (via PAG) –turning head/eye towards painful stimuli
92
Spino-emotional
to midline/intralaminar nuclei in thalamus

Neuroscience (4 decks)

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