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1019 Neuro > Descending Pathways > Flashcards

Descending Pathways Flashcards

1
Q

What are the pyramidal pathways in the nervous system?

A

Lateral CORTICOSPINAL

Anterior CORTICOSPINAL

CORTICOBULBAR

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2
Q

What is the function of the LATERAL CORTICOSPINAL tract?

A

Voluntary movement of UL and LL (distal>proximal muscles)

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3
Q

What is the pathway of the LATERAL CORTICOSPINAL tract?

A

UMN cell body in primary motor cortex
(arm region – more lateral, or leg region – medial, in sagittal fissure)

Descends through corona radiata -> posterior limb of internal capsule (arm – trunk – leg from anterior to posterior in posterior limb) -> through cerebral peduncle (middle 1/3) -> base of pons

Decussates at medullary pyramids

Travels in lateral white column until cervical lumbosacral spinal cord

Synapses in anterior horn with LMNs (more lateral for distal limb in anterior horn) -> LMN travels to muscle

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4
Q

What is the function of the ANTERIOR CORTICOSPINAL tract?

A

Voluntary movement of trunk and proximal limb

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5
Q

What is the pathway of the ANTERIOR CORTICOSPINAL tract

A

UMN starts in superior region of M1 (trunk region)

Descends through corona radiata -> posterior limb of internal capsule (middle section of posterior limb) -> middle 1/3 of cerebral peduncle ->base of pons

Descends through medullary pyramid but stays ipsilateral

Travels down spinal cord in anterior corticospinal tract -> bilaterally innervates trunk muscles (most medial section of anterior horn) (crosses at anterior white commissure).

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6
Q

What is the function of the CORTICOBULBAR tract?

A

Voluntary movement of the face

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7
Q

What is the pathway of the corticobulbar tract?

A

UMN starts in head/face region of M1

Descends through corona radiata ->GENU of internal capsule -> travels into cerebral peduncles

UMN’s of different cranial nerves decussate at different levels (at the level of the cranial nerve nuclei.)

Some fibres remain ipsilateral and supply the ipsilateral cranial nerve nuclei
(3, 4 = midbrain; 5, 6, 7 = pons; 9, 10, 11, 12 = medulla).

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8
Q

What are the EXTRAPYRAMIDAL tracts in the nervous system?

A

Rubrospinal tract

Tectospinal tract

Reticulospinal tract

Vestibulospinal tract

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9
Q

What is the function of the EXTRAPYRAMIDAL tracts?

A

Involuntary Innervation of:

Trunk and Proximal limb muscles
Posture/Balance/Equilibrium
Regulate muscle tone

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10
Q

What is the function of the RUBROSPINAL tract?

A

Only FLEXOR-BIASED pathway, mainly in rhe Upper limb

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11
Q

Outline the RUBROSPINAL tract

A

UMN originates in the red nucleus

Decussates in the midbrain

Travels through tegmentum

Descends through pyramids and through the Lateral Column of the spinal cord

Terminate on LMNs in the anterior horn of spinal cord that innervate flexor muscles of the upper limb

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12
Q

What tract does the rubrospinal tract run with?

A

Lateral corticospinal tract

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13
Q

What is the function of the TECTOSPINAL tract?

A

EXTENSOR-BIASED

works bilaterally to control reflex movements of the head, neck and upper limbs in response to stimuli (eye movement)

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14
Q

Outline the TECTOSPINAL pathway

A

UMN originates in the Superior Colliculus

Decussates in the midbrain

Travels through tegmentum

Descends through pyramids

UMN synapse in Anterior White Column

LMN Projects into the Anterior horn of the cervical spinal cord to orientate the head and neck during eye movements

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15
Q

What is the function of the Reticulospinal tract?

A

EXTENSOR-BIASED

Maintains body posture/tone through movement

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16
Q

What is the pathway of the RETICULOSPINAL tract?

A

UMN originates in the Reticular Formation

Travels ipsilaterally through brainstem

UMN synapses in the anterior white column

Terminates on the LMN circuits in the anterior horn of each spinal cord, throughout the length of the cord.

17
Q

What is the function of the VESTIBULOSPINAL TRACT

A

Receives information from FASTIGIAL nucleus in the Vestibulocerebellum

Alter muscle tone, extend and change the position of the limbs and head in order to maintain posture and balance of the body and head

18
Q

What is the pathway of the MEDIAL VESTIBULOSPINAL/ MEDIAL LONGITUDINAL FASCICULUS tract?

A

UMN originates in the vestibular nuclei in the caudal pons/rostral medulla

Descends bilaterally through brainstem

Travels in anterior white column of spinal cord

Terminates on LMN circuit neurons of cervical and upper thoracic levels

19
Q

What is the pathway of the LATERAL VESTIBULOSPINAL TRACT?

A

UMN originates in the vestibular nuclei in the caudal pons/rostral medulla

Descends ipsilaterally through anteromedial brainstem

Travels in anterior white column of spinal cord

Terminates on LMN circuit neurons in the anterior horn of all spinal levels

20
Q

What is the function of the LATERAL VESTIBULOSPINAL tract?

A

Ipsilateral excitatory to extensors. Inhibitory to flexors

1019 Neuro (9 decks)

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