Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Neuroscience (By Chapter) > Ch. 10: Motor System: Motor Neurons > Flashcards

Ch. 10: Motor System: Motor Neurons Flashcards

(72 cards)

Start Studying
1
Q

Ongoing Voluntary Movement

A

sensory info (from spindles, tendon organs, skin rec etc) may modify movement at level of motor planning area and/or central circuit and/or spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

LMN

A
  • Lower motor neurons
  • “peripheral” motor neurons
  • Start in ventral horn and go to Mm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

UMN

A
  • “central”/upper motor neurons
  • from brainstem/cortex to spinal cord
  • 2 types: medial and lateral
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Lateral UMN

A
  • Fine motor tracts
  • control peripheral Mm
  • connect to LMN that go to peripheral Mm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

:Active Stiffness:

UMN

A

UMN–>activation of LMG
-conscious & intentional
or
-unconscious & unintentional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Intrinsic Stiffness

A
  • weak actin-myosin attachment in resting state
  • “velcro”
  • happens after a muscle is immobile for a while
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Sarcomere Remodeling

A
  • Mm immobilized in shortened position results in decreased number of sarcomeres=contracture (bad)
  • Mm immobilized in lengthened position results in an increased number of sarcomeres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

M Line

A

anchors myosin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Z Line

A

anchors actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Titin

A
  • Structural protein that connects M line to Z line

- increases structural integrity of sarcomere contributes to stiffness of Mm at end range

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

:Active Stiffness:

Reflex Activity

A
  • branches of sensory neurons can activate LMN reflexively

- (Patellar tendon reflex)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Passive Stiffness

A
  • Elastic resistance of titin
  • particularly troublesome with contractures
  • muscle shorter than it should be
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Medial UMN

A
  • postural/gross motor
  • control midline/proximal Mm
  • connect to LMN that go to midline Mm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

4 factors of Mm Stiffness

A
  • Active Stiffness: UMN activating LMN
  • Active Stiffness: reflex activity
  • Intrinsic Stiffness
  • Passive Stiffness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Cocontraction

A
  • “joint stiffness”
  • partial/full contraction of Mm on both sides of a joint or around a body segment
  • Static/Dynamic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Static Cocontraction

A

Stiffly locking a joint

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Dynamic Cocontraction

A

control movement of a joint

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

2 Types of LMN

A
  • Alpha motor neurons (to extrafusal Mm)

- Gamma motor neurons (to intrafusal Mm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Henneman’s Size Principle

A
  • order of recruitment
  • Slow twitch first, then fast twitch
  • EXCEPTION: when you need explosive/high level force right away
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

alpha-gamma coactivation

A
  • UMN send parallel signals to alpha and gamma neurons

- contracts Mm (alpha) and keeps spindle sensitive (gamma) to stretch during contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Motor Neuron Pools

A
  • Clusters of LMN somas in grey matter of spinal cord arranged in vertical fusal shapes (fusiform)
  • axons project to a single muscle per pool
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Motor Unit

A
  • one alpha motor neuron & all the Mm fibers it’s connected to
  • slow OR fast (not mixed)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Size of Motor Units

A
  • Gross Motor Control has many Mm fibers for each motor axon

- Fine Motor Control has few Mm fibers for each motor axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Convergence of info to alpha motor neuron

A
  • each LMN gets input from a variety of sources

- Sources include: UMN, sensory receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Vertical Orginization of Neuron Pools
- single pool may include several spinal levels and myotomes | - every Mm gets innervation from 2+ spinal levels
26
Horizontal Organization of Neuron Pools
- Medial Pools: axial and proximal Mm - Lateral Pools: distal Mm - Anterior: Extensor Mm - Posterior: Flexor Mm
27
Muscle Synergies
-Many Mm working/contracting together -activation of multiple UMN OR -UMN branching to several UMN OR -Interneuron Networks
28
Phasic Stretch reflex
- Spinal region reflex from Mm spindles to LMN (alpha) - Quick stretch to a spindle-->Ia fiber-->monosynaptic connection with alpha motor neuron of same Mm-->brief activation of alpha motor neurons of same Mm
29
UMN Director Tracts
- Start in cerebral cortex - end in ventral horn spinal cord - 2 divisions: medial/lateral - highest amount of voluntary control of movement
30
UMN Director Tract: | Medial Division
-to LMN of proximal arm/leg Mm
31
UMN Director Tract: | Lateral Division
-to LMN of distal arm/leg Mm
32
Reciprocal Inhibition
- when 1 Mm contracts the antagonist relaxes - connections from UMN to alpha motor neurons - connectiosn from Mm spindle afferents to alpha motor neurons - uses an interneuron
33
Normal Mm Synergies vs Abnormal
-group of Mm that work together under control for a functional outcome VS -group of Mm working together w/o control and don't produce functional outcome
34
Withdrawal Reflex
- spinal region reflex from cutaneous receptors to LMN (alpha) - pain-->A delta neurons-->multisynaptic connection with alpha motor neurons-->automatic w/d of painful limb (one pain fiber splits to many spinal levels)
35
UMN Helper Tracts
- Start: in brain stem - End: in ventral horn - medal/lateral divisions - lowest level of voluntary control (hold me up against gravity/pick up against gravity)
36
UMN Helper Tracts: | Medial Division
-to LMN that control prox arm/leg Mm
37
UMN Helper Tracts: | Lateral division
-to LMN that control distal leg/arm Mm
38
director UMN help control_______
activation of helper UMN in brainstem
39
Paralysis
inability to move
40
Atrophy
- shrinking of Mm bulk | - disuse versus denervation
41
Paresis
- weakness | - difficulty moving
42
Myoclonus
-rhythmic & repetitive involuntary contraction of the whole muscle
43
3 Descending Motor Tracts
- Lateral activation system - medial activation system - Nonspecific activation system
44
Motor planning areas send _____
movement signals to director and helper UMN
45
7 Involuntary Mm Contractions
1. Mm spasms 2. Mm Cramps 3. Fasciculation 4. Mhyoclonus 5. Tremor 6. Firillations 7. Abnormal Movement from dysfunctional basal ganglia
46
Lateral Activation System
- Axons in Lateral columns connect to LMN in ventral horn | - 2 pathways (lateral corticospinal tract, rubrospinal tract)
47
2 Pathways of Lateral Activation System
- lateral corticospinal tract | - rubrospinal tract
48
Mm Spasms/Cramps
- involuntary Mm contraction | - problem at Mm level
49
Hypotonia
- flaccidity | - decreased muscle tone
50
Fasciculations
- contraction of entire motor unit | - sign of NS irritation
51
Tremor
- shaking back and forth of limb | - at rest (Parkinson's sign) vs Intention (cerebellar damage)
52
Fibrillations
- spontaneous depol of 1 denervted Mm fiber - can't see - evidence of severe nerve damage
53
Hypertonia
- increased tone - spasticity (Velocity dependent) - Rigidity (nonvelocity dependent)
54
5 S/Sx of LMN Disorder
1. loss of reflexes (stretch and cutaneous) 2. atrophy of denervation 3. disorders of Mm tone 4. paralysis (flaccid) 5. fibrillations
55
5 S/Sx UMN Disorders
1. Paresis/paralysis 2. loss fractionated movement 3. abnormal reflexes 4. disorders of Mm tone 5. disorders of Mm contraction
56
Mm Stretch hyperreflexia
- exaggerated Mm response to a quick stretch - LMN not getting inhibitory signal from damaged UMN, so post synaptic membrane upregulates more receptors to get a signal and causes increased strength of reflexes
57
Clasp Knife Response
- catch and release | - muscle stretch hyperreflexia (catch) that relaxes (release)
58
Rigid Hypertonia
- UMN damage-->send too many signals all the time - nonvelocity dependent - ex. Parkinson's
59
Clonus
-repeated stretch hyperreflexia
60
Spastic Hypertonia
- Mm stretch hyperreflexia | - velocity depenent
61
Decerebrate Rigidity
- whole head cut off from brainstem - unconscious tonic rigidity in arm and leg extensors - Ex. TBI
62
Decorticate Rigidity
- cut off from cortex - unconscious tonic flexion of arms and extension of legs - ex. TBI
63
6 Disorders of Mm contraction
1. delayed initiation 2. slow force production 3. prolonged contraction time 4. disordered corrdination of agonists and antagonists 5. decreased fractionation 6. abnormal (stereotyped) Mm synergies
64
Myoplastic Hyperstiffness
- due to paresis & habitual positioning - increased stiffness from increased intrinsic stiffness and connective tightness - not due to increased tone - decreased sarcomere number (contractures) - increased weak binding actin/myosin from decreased movement - selective loss fast twitch fibers
65
Mm overactivity
- unconscious - excess tone is activity dependent - ex. stroke - at rest no hypertonia - moving increases hypertonia
66
4 types of Mm hyperstiffness
- myoplastic hyperstiffness - spasticity - rigidity & Mm overactivity - Mm overactivity
67
Abnormal Tone
- hypotonia - hypertonia - shock
68
Shock
- period of time after trauma when motor neurons are unexcitable - cerebral--post stroke - Spinal--post SCI - may wake up again
69
Example of LMN Disorders
- peripheral N injury | - ALS
70
ALS
- Amyotrophic Lateral Sclerosis | - LMN in ventral horn attacked and die all the way out to the periphery
71
2 Types of Rigid Hypertonia
- decerebrate - decorticate (too many signals all the time)
72
3 disorders of Mm tone
(hypertonia) 1. spastic hypertonia 2. rigid hypertonia 3. Mm overactivity

Neuroscience (By Chapter) (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions