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CBL neuro > descending tracts > Flashcards

descending tracts Flashcards

1
Q

Key areas of the motor system - heirarchial organisation

A

Cerebral cortex -decision to move
Brain stem
Spinal cord

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2
Q

Parallel organisation of the motor system

A

Basal nuclei
Thalamus
Cerebellum
involved in coordinating, regulating and fine tuning

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3
Q

Generation of voluntary movement for eg throwing ball

A

Identify target/goal and locate it - VISUAL SYSTEM, retinotopic space

Determine limb trajectory ( body or hand centered system)

Calculate forces necessary to generate desired trajectory ( muscle based reference frame)

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4
Q

motor cortex

A

Cortical regions involved in movement plan control and initiate movement
primary, premotor, supplementary, cingulate

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5
Q

Motor area

A

Movement can be evoked by the LOWEST STIMULUS INTENSITY

- anatomical experiments

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6
Q

Primary motor cortex

A

location on the pre central gyrus
Somatotopic map
Neurones directly related to movement- specific parts f the body from spinal cord to cortex
Motor homunculus

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7
Q

Left side of brain controls

A

RIGHT SIDE OF BODY

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8
Q

Feedback control

A

Sensory info from voluntary movements are sent to the cerebrum and cerebellum

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9
Q

Error signal

A

Difference between desired and actual position

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10
Q

Feed forward control

A

Sensory info gives advanced info

  • Anticipation of the required movement
  • Enables movement to be direction to the target
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11
Q

Describe motor output from brain

HEIRARCHICAL SYSTEM

A

Target of movement identified by a pooling of sensory info in teh posterior parietal cortex combined with info from the primary sensory cortex

Info transmitted to the supplementary motor and pre motor areas( planning)

Primary motor cortex 
Commands transmitted(via descending pathways) to spinal cord and brain stem motor nuclei
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12
Q

Motor output - PARALLEL DISTRIBUTION NETWORK

A

Numerous motor areas are all bidirectionally connected
Each area contributes to several stages of planning and executing a movement
Each cortical area makes a significant contribution to descending pathways

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13
Q

Word to describe the motor descending pathway

A

TOPOGRAPHICALLY ORGANISED

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14
Q

2 TYPES OF NEURONES in the motor pathway

A

Upper motor neurone - cell body in primary motor cortex of the frontal lobe

lower body neurone-synapses on the lower motor neuron, which is in the ventral horn of the spinal cord and projects to the skeletal muscle in the periphery.

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15
Q

limb muscles - descending tract

A

Column extends for several segment
Lateral part of ventral horn
Distal part of limb, proximal muscles

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16
Q

Axial musculature - descending tract

A

Column/tract extend greater length of spinal cord
Medial part of ventral horn
Interneurones enable bilateral innervation ( postural support)

17
Q

2 main groups of descending motor pathways

A

Dependent on location of tract

LATERAL
MEDIAL

18
Q

LATERAL pathways

A

Control proximal distal muscles
Responsible for most voluntary movements of arms and legs
Lateral corticospinal tract and rubrospinal tract

19
Q

MEDIAL pathways

A

Control anti gravity muscles
Control axial and postural muscles = posutre and balance
anterior corticospinal tract, tectospinal tract, vestibulospinal tracts, reticulospinal tracts

20
Q

Corticospinal ( pyramindal ) tract

A

COntrols musles of distal limbs and trunk
FINE MOTOR MOVEMENT
Longest and largest CNS descedning tract
Motor cortex — spinal cord
Form medullary pyramids
Decussation at medullary spinal cord junction

21
Q

lateral corticospinal tracts Function and route

A

Function:
Controls muscles of distal limbs, voluntary movements of arms and legs, fine movement of contralateral limbs

Route:
Originates in cerebral cortex
Upper motor neurones decussate in the medulla 
Runs in lateral tract in spinal cord 
Innervate lateral lower motor neurones
22
Q

Anterior corticospinal tract

FUNCTION AND ROUTE

A

Function

  • Controls trunk muscles
  • Responsible for maintaining posture
Route 
- Originates in cerebral ortex 
Upper motor neurones DO NOT decussate in medulla
Smaller than lateral pathway 
Runs in anterior tract in spinal cord 
Innervate medial lower motor neurones
23
Q

Corticonuclear tract

A

Originate in motor cortex
Terminates in brain stem nuceli
Innervates cranial nerves - face, jaw and tongue movement

Most nuclei receive bilateral innervation from cortex EXCEPT - facial motor nucleus and hypoglossal nucleus

24
Q

rubrospinal tract

A

Originates in red nucleus( brainstem)

Voluntary movement of upper limbs and shoulders

25
Q

Vestibulospinal tract

A

Originates in vestibular nucelus
Controls muscles of neck, trunk adn some legs
Upright posture

26
Q

Tectospinal tract

A

Originates in superior colliculus in midbrain
Info from eyes and visual cortex
Innervate contralateral motor neurones controlling head position

27
Q

Reticulospinal tracts

A

Pontine
Medullary
Innervate interneurons affecting corticospinal tract

28
Q

Where does reticulospinal tracts originate

A

Originates from reticular formation (pons and medulla)

29
Q

Potine reticulospinal tract

A

Ipsilateral innervation of extensor motor neruones

30
Q

Medullary reticulospinal tract

A

Bilateral innervation of flexor motor neurones

31
Q

Innervate interneurons affecting corticospinal tract - reticulospinal tracts

A

Modulates voluntary movements, aid locomotion and posture, influences muscle tone

32
Q

How can level of damage to motor pathways show differently

A

Dictates
Damage between upper and lower limb trunk - paraplegia
Tetraplegia - higher up spinal cord= upper motor neurons , loss of upper limb movement

33
Q

effect of upper motor neuron damage

A

Damage in cortex/brain stem/spinal cord - any point
HIGHER LEVEL DAMAGE
Cortex involved with long term planning and execution - release
effects long term planning and execution
Different activity in brain stem, different patterns in lower motor neurones- incorrect, or may stop working all
Specific regions affected

34
Q

Lower motor neuron damage

A

Damage to the alpha motor neurones that innervate skeletal muscle
Effects small groups of muscles (motor unit)

35
Q

Upper motor neurone syndrome symptoms

A 
Paralysis of movements 
Increased muscle tone 
Hyperactive stretch reflexes 
Extensor plantar reflex ( babinski sign)
Reduction in superficial reflexes
36
Q

Lower motor neurone syndrome symptoms

A

Paralysis of muscles
Hypotonia and atrophy of muscles
Fasciculations and fibrillations
Loss of stretch reflexes but superficial reflexes are maintained

37
Q

Babinski reflex

A

When do reflex that makes toes go down

CBL neuro (9 decks)

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