Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuro I > Intro to Motor Systems > Flashcards

Intro to Motor Systems Flashcards

1
Q

Motor Systems Concepts

A

Somatic Motor System (GSE)

  • movements intitiated (or modulated by) voluntary intent
  • targets = striated mm
  • reflex component

Visceral Motor System (GVE)

  • part of autonomic nervous system
  • targets = smooth/cardiac m, glands
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Motor Systems Concepts

A

Motivation (frontal lobe)

  • ideation of motor plan
  • input from
    • sensory stimuli (parietal motor area)
    • emotions/memory (limbic syste)

Motor Plan (premotor cx)

  • blueprint or module for movement
  • premotor cx (lateral BA6 & 8)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Motor Systems Concepts

A

Action (primary motor cx)

  • UMN systems
  • locations:
    • primary motor cx
    • brainstem nuclei
  • UMN fibers influence motor neurons in spinal cord (& cranial n motor nuclei) = LMN
  • All systems converge on LMNs to provide movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Alpha LMNs

A

Synapse on skeletal muscle

Final common pathway

Always excitatory - release NT=contraction

Target ipsilateral to soma

Large

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

Alpha LMNs continued

A

Found in

  • sp cord ventral horn & cranial nerve motor nuclei

Have baseline activity, changed by excitatory & inhibitory inputs

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

Motor Units

A

Motor Unit = 1 LMN + all m fibers it innervates

Size related to function (fine control vs power)

  • small number for fine control

1 LMN innervates many fibers

Each m fiber has motor units of various sizes (although certain sizes may predominate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Motor Units Continued

A

AP in motor axon is “all or nothing”

Regulate strength of muscle contraction via

  • AP frequency
  • Recruitment (#motor units firing proportional to strength)
    • ordered by size (smaller motor units recruited first, then larger)
    • “Size Principle”
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Upper Motor Neurons

A

Axons from brain, influence LMN

  • Directly (few) or indirectly (most)
  • Excitatory or inhibitory

Never synapse on muscle

Cerebral cx & brainstem

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

UMN

A

8 different UMN pathways drive LMNs in spinal cord

  • 2 from primary motor cx
  • rest from brainstem nuclei

Lateral Motor System

  • Distal limb mm
  • precise, fractionated movements

Medial Motor Systems

  • Axial/Proximal limb mm
  • Postural movements
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Intro to Cortical UMN Systems

A

Two Cortical UMN Pathways:

  • Corticospinal Tract (Lateral
  • Corticobulbular Tract

Important features of LCST:

  • large motor tract of humans
  • contralateral projections
  • some UMNs synapse directly on LMNs
  • critical for complex, fractionated movements
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Anatomy of the LCST

A

Premotor Cx - lateral BA6 &8

Motor planning

  • most active at start of voluntary movement

Supplementary Motor Cx - medial BA6 & 8

Motor planning

  • interconnected w/contralateral side = bimanual movements
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Corticobulbar Tract

A

Corticobulbar similar to corticspinal, except:

  • Terminate in brainstem
  • Influences
    • cranial nerve motor nuclei (LMNs)
    • AND UMN nuclei
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Corticobulbar fibers ALSO:

A

Influence activity in brainstem UMN nuclei

  • vestibular nuclei
  • reticular nuclei
  • red nucleus

These nuclei give rise to medial motor systems (control of axial/proximal limb mm) - gain voluntary control of these by sending info from cx to these nuclei via corticobulbar tract

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

LMN Damage

A
  • LMN damage produce LMN signs
  • Hypo- to Areflexia (continuum)
    • hypo- to Atonia - decrease stretch reflex
  • Paralysis/paresis
    • loss of trophic relationships w/motor neuron
    • neurogenic atrophy
  • EMG changes: spontaneous activity in mm
  • fasciculations and fibrilations
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

UMN Damage

A

Produces UMN Signs

  • Normal to Hyperreflexia
    • Increase stretch reflex - hypertonia
    • Appearance of pathological reflexes
  • Paresis/paralysis
    • spastic (especially in antigravity mm)
  • Disuse atrophy
  • Few EMG changes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why are reflexes sometimes increased w/UMN damage?

A

Loss of normal inhibitory background

Sprouting of local afferents (increased output)

Denervation hypersensitivity

  • increased expression of receptors on surface of LMNs & interneurons
17
Q

Damage to Corticospinal system:

Where will deficit manifest?

A
  • All levels at and below lesion
  • LMN signs at lesion level
  • UMN signs inferior to lesion:
    • Lesions above decussation = contralateral signs
    • Lesions below decussation = ipsilateral signs
18
Q

Non-Cortical UMN Systems

A

Take origin in sites other than cx - aka extrapyramidal systems

Affect primarily axial/proximal limb mm

Important in reflex postural movement

Also under voluntary control (from cx via corticobulbar tract)

Axons of most are ventromedial in cord (i.e., part of “medial motor system”)

19
Q

Rubrospinal Tract

A
  • Cells bodies: red nucleus
  • Axons decussate in midbrain, descend in contralateral lateral funiculus
  • Primarily effect: (+)(-) to distal mm of arms (cervical cord only)
  • Primarily arm/forearm flexors
  • Very small in humans
20
Q

Vestibulospinal Tract

A

Medial & Lateral VST

  • M/L described in cord & nucleus of origin

Cells bodies:

  • MVST - medial/inferior vestibule nucleus
  • LVST - lateral vestibule nucleus

In cord:

  • MVST = bilateral, through cervical and upper thoracic
  • LVST = ipsilateral, thru-out cord
21
Q

Vestibulospinal Tracts continued

A
  • MVST (aka descending MLF)
    • Acts on neck mm (+/-)
    • Changes in head/neck posture (bothe reflex & voluntary activity
  • LVST
      • to axial, antigravity mm
    • changes in trunk posture (both reflex & voluntary activity)
22
Q

Medial Longitudinal Fasciculus (Ascending Portion)

A
  • Commonly: MLF
  • Cell bodies: medial/inferior vestibule nucleus
  • Ascends to innervate motor nuclei of III, IV, VI (LMNs innervating extraocular mm)
  • Bilateral, +/- effects
23
Q

Reticulospinal Tract

A
  • Medial & Lateral RST
    • M/L refers to location in cord
    • MRST aka pontine RST
    • LRST aka medullary RST
  • Cells bodies: reticular formation
  • LRST bilateral
  • MRST ipsilateral
  • Reticulospinal tracts may be “back up” pathways for voluntary movements w/injury to corticospinal tracts (+/- effects)
24
Q

Tectospinal

A
  • Cell bodies: Superior colliculus
  • Decussates in midbrain (contralateral)
  • Synaptic effect: (+)(-) to neck mm (tract terminates in cervical cord)
  • visual grasp reflex

Neuro I (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions