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VET260 > Spinal Tracts > Flashcards

Spinal Tracts Flashcards

1
Q

What is the function of cerebral cell bodies of the cortex?

A

Initiate, maintain and plan voluntary movement

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2
Q

What is the function of Cell bodies of the brainstem?

A

regulation of muscle tone. posture and basic navigational movement

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3
Q

Where are the cell bodies of the CNS Upper Motor Neurons located?

A

cerebral cortex

brainstem

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4
Q

Where are the axons of the UMNs located?

A

white matter of the spinal cord

synapse in ventral horn grey matter with inter neurons or LMN

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5
Q

List the 5 main upper motor neuron pathways.

A

Corticospinal Tract (lateral and ventral)
Rubrospinal Tract
ReticuloSpinal (medullary and pontine) Tracts
Tectospinal Tract
Vestibulospinal Tract

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6
Q

Where does the corticospinal tract originate and insert. List the structures it passes through.

A 
O: cerebral cortex
Travels through:
red nucleus
crus cerebri 
pyramids
I: lateral or ventral corticospinal tract
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7
Q

How does the pathway of the lateral corticospinal tract differ to the ventral tract?

A

75% of the neurons will decussate at the medulla to insert in the lateral corticospinal tract

Remaining 25% of neurons will continue ventrally to insert on the ventral corticospinal tract

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8
Q

Name where along the vertebrae the lateral corticospinal tract will insert.

A

50% cervical grey matter
20% thoracic grey matter
30% lumbosacral grey matter

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9
Q

What is the function of the llateral and ventral corticospinal tracts?

A

Lateral: flexion and fine activity
ventral: axial and proximal limb muscles contribute to posture

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10
Q

Which group of species is the corticospinal tract most prevalent?

A

primates

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11
Q

Name the origin and insertion of the rubrospinal tract.

A

O: red nucleus of midbrain –> axons immediately decussate at brainstem
I: lateral funiculus of spinal cord: rubrospinal tract

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12
Q

What is the function of the rubrospinal tract?

A

enables motor cortices indirect functioning in semi skilled movement in cats and locomotion : limb protraction

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13
Q

Name the origin and insertion of the Reticulospinal tracts, listing the structures that it passes.

A

O: cerebral cortex
Medullary: reticular formation of the medulla
Pontine: reticular formation of the pons
I: lateral funiculus (medullary), ventral funiculus (pontine)

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14
Q

What is the function of the reticulospinal tracts?

A

Medullar: ipsilateral and contralateral strong inhibitor of y-LMN of extensor muscles and excitation of flexors

Pontine: stimulates ipsilateral y-LMNs antigravity extensor muscles

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15
Q

What is the origin and insertion of the lateral and medial vestibulospinal tracts?

A

O: vesibular nuclei of the brainstem

  • lateral: lateral vestibular nucleus
  • medial: medial, rostral. caudal vestibular nuclei

I:
Lateral: ipsilateral ventral funiculus, all levels spinal cord esp intumescences. Some decussate to inhibit contralateral LMNs

Medial: medial aspect ventral funiculus + medial longitudinal fasciculus, cervical and cranial thoracic

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16
Q

What is the function of the lateral and medial vestibulospinal tracts?l

A

Overall: maintenance and balance
Lateral: senses static head position –> maintanence of posture against gravity through extensor activity and inhibition of flexors

medial: reinforces activity in cervical and thoracic limb muscle maintains posture despite changes to head position

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17
Q

What stimulates the Lateral vestibulospinal tract to stimulate extensors and inhibit flexors?

A

input from utricle (forwards and back wards motions)
saccule (up and down motion)
–> static head position

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18
Q

What activates the medial vestibulospinal tract?

A

angular acceleration of head detected by vestibular apparatus

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19
Q

What is the origin and insertion of the tectospinal tract?

A

O: rostral and caudal colliculi of midbrain (visual tectum)
I: ventral funiculus, cervical and upper thoracic spinal cord

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20
Q

What is the function of the tectospinal tract?

A

maintenance of balance and posture.

reflex and postural movements of head and neck in response to visual and auditory stimuli through control of the axial musculature of neck

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21
Q

What is the main function of the tracts located within the ventral funiculus?

A

stimulators of extensor muscles

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22
Q

What is the main function of the tracts of the lateral funiculus?

A

stimulators of the flexor muscles or inhbitors of extensors

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23
Q

Which spinal tracts do not run the entire length of the spinal cord?

A

tectospinal tract

medial vestibulospinal tract

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24
Q

What is the function of the spinothalamic ventrallateral tract?

A

Ventral: crude touch, pressure

Lateral: temperature, pain

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25
Q

Describe the pathway of the spinothalamic ventral lateral pathways.

A

1st order neuron: dorsal root ganglion
2nd order neuron: synapse in dorsal horn grey matter decussates to other side
3rd order neuron: synapse at ventral posterior lateral nucleus of the thalamus and inserts at the cerebral cortex

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26
Q

What is the function of the dorsal column medial laminuscus system?

A

conscious proprioception
vibration
tactile sensation
two point discrimination

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27
Q

How does the fibers of the fasiculus gracillus differ to the fasiculus cuneatus?

A

fasiculus gracillus: information from lower part of the body, present throughout spinal cord
fasiculus cuneatus: info from upper body, not present below T6

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28
Q

What is the function of the spinocerebellar systems?

A

unconscious proprioception (doesnt ascend to cerebral cortex)

provide cerebellum with spatial information about trunk and limbs during movement and during fixed posture

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29
Q

How many neurons does the spinocerebellar system consist of?

A

2 neurons as there is no third required to reach the cerebral cortex

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30
Q

Describe the pathway of the ventral spinocerebellar system

A

1st order neuron: dorsal root ganglion
2nd order: decussates to opposite site entering spinocerebral tract –>
continues dorsally until reaches the cranial cerebral peduncle –>
decussates to opposite side

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31
Q

Describe the pathway of the dorsal spinocerebellar system and how it differs from the pathway of the ventral spinocerebellar system.

A

1st order neuron: dorsal root ganglion
2nd order: synapses at dorsal horn grey matter –> ascends the same side (no decussation)–>
ventral cerebellar peduncle (medulla connection to cerebellum)

32
Q

What is the function of the spinaltectal tract?

A

regulates spinovisual reflexes

33
Q

Where does the spinotectal tract insert.

A

cranial colliculus (midbrain)

34
Q

What are the 4 mechanoreceptors of the skin?

A

Ruffini ending
Pacinian corpuscle
Merkel disc receptor
Meissner’s corpuscle

35
Q

Where do the fasciculus gracilis and cuneatus tracts lay within the vertebral column?

A

fusciculus gracilis: caudal to T6

fasciculus cuneatus: cranial to T6

36
Q

What is the general function of the trigeminal pathway?

A

carries information from the face

37
Q

Describe the pathway of the trigeminal tract.

A

1st neuron: trigeminal ganglion –> synapse at principle nucleus of tigeminal complex

2nd order: immediately decussates at the level of the midbrain through the medial lemniscus –> synapses in ventral posterior medial nucleus of thalamus

3rd order: synapses in primary somatic sensory cortex

38
Q

Describe the pathway of the dorsal column medial lemniscus tract with reference to the funiculus gracilis.

A

1st order neuron: dorsal horn grey matter at level of lumbar spinal cord –> continues dorsally ipsilaterally

2nd order: synapse at gracile nucleus in the caudal medulla and decussates immediately –> continues through medial leminiscus until reaches thalamus (VPL nucleus)

3rd order: towards primary somatic sensory cortex

39
Q

Describe the pathway of the dorsal column-medial leminiscus pathway with reference to the fasciculus cuneatus.

A

1st order: dorsal horn grey matter at level of the cervical spinal cord –> continues ipsilaterally

2nd order: synapses at cuneate nucleas in caudal medulla –> decussates immediately –> continues through medial leminiscus of midbrain until the VML nucleus of the thalamus

3rd order: synapses at the primary somatic sensory cortex

40
Q

Name the branches of the trigeminal nerve.

A

ophthalmic
maxillary
mandibular

41
Q

How does the function of the dorsal and ventral spinocerebellar tracts differ from the rostral spinocerebellar and spinocuneocerebellar tracts?

A

ventral and dorsal spinocerebellar: information received from pelvic limbs and trunk

rostral and cuneo: information received from thoracic limbs

42
Q

Name all the tracts of the spinocerebellar pathway.

A

Dorsal spinocerebellar
ventral spinocerebellar
rostral spinocerebellar
spinocuneocerebellar

43
Q

Provide a general description of the pathways occurring below L3/L4 for the spinocerebellar tract

A

1st order: ascend in in fasciculus gracilis
2nd order: synapse in nucleus of dorsal spinocerebellar tract or ventral spinocerebellar tract–> ipsilaterally to cerebellum

44
Q

Describe the pathway of the spinocuneocerebellar tract.

A

1st order: C1 to T8 axons ascend in fasciculus cuneatus

2nd order: synapse in lateral accessory cuneate nucleus –> ipsilateral cerebellum via spino cuneocerebellar tract

45
Q

What would be the effect of a lesion at C1-C5?

A

Loss of proprioception and sensory input of the thoacic and pelvic limbs, tail and trunk

UMN signs in the TL and PL

No LMN signs in TL or PL. Cutaneous trunci and perineal reflexes intact.

UMN bladder and faecal incontinence

46
Q

What would be the effect of a lesion within C6 to T2?

A

Loss of proprioception and sensory input from TL, PL, trunk and tail.

UMN signs in PL only.

LMN signs present in TL only, loss of cutaneous trunci reflex if lesion in C8-T1
perineal reflex intact

UMN bladder, faecal incontinence

47
Q

What would be the effect of a lesion within T3-L3 (thoracolumbar)?

A

loss of proprioception and sensory input of the trunk caudal to the lesion, PL and tail

Presence of UMN signs in PL

no LMN signs in TL and PL
cutaneous trunci reflex lost caudal to lesion
perineal reflex intact

UMN bladder, faecal incontinence

48
Q

What would be the effect of a lesion within the cranial lumbosacral region (L4-S1)

A

Loss of proprioceptive and sensory input at the PL and tail

No UMN signs to limbs

LMN signs in PL

cutaneous trunci and perineal reflexes intact

UMN bladder
faecal incontinence

49
Q

What would be the effect of a lesion in the caudal lumbosacral region (S1-S3)?

A

Loss of priprioceptive and sensory input at the perineum, tail
PL probably normal

No UMN signs to limbs

LMN signs in pelvic viscera

loss perineal reflex

LMN bladder and anal sphincter –> incontinence with dropping faeces via dilated anus

50
Q

What would be the effect of a lesion within the caudal nerves (Cd1-5)?

A

loss of sensory and proprioceptive input at the tail.

No UMN signs

LMN signs in tail

normal continence

51
Q

What is meant by an UMN bladder?

A

turgid, full, difficult to express

52
Q

what is meant by a LMN bladder?

A

flaccid, distended, easily expressed, dribbling urine

53
Q

Where are the cell bodies of nociceptors located?

A

trigeminal ganglion

dorsal root ganglion

54
Q

Where are the proprioceptive receptor organs located?

A

muscle
tendon
joints

55
Q

List the 4 categories of skin nociceptors.

A

high threshold mechanonociceptors: intense mechanical stimulation IE pinching, cutting etc.

thermal nociceptors

chemical nociceptors

polymodal nociceptors: high intensity stimuli such as mechanical, thermal and chemical

56
Q

List the characteristics of the C-fibre mechano-heat sensitive axons.

A

small unmyelinated axons

slow conducting

l

57
Q

what type of stimuli does C-fibre mechano heat sensitive fibers respond to?

A

deep, visceral, burning and aching pains

–>

high intensity mechanical, chemical and thermal stimulation

58
Q

Compare the precision of pain reception in the C-fiber mechano heat and A-fiber mechano heat sensitive fibers.

A

C fibers: large receptive field –> less precise pain localisation

A-fibers: small receptive fields –> precise localisation of pain

59
Q

Compare the synapse location of C-fiber mechano heat sensitive and A-fiber mechano heat sensitive fibers in the dorsal root horn.

A

C fibers: rexed layer 1 or 2 (substantia gelatinosa) depending on fiber class type

A fibers: rexed layer 1 (nucleus posterior marginalis)

60
Q

What type of pain does the A fiber mechano heat sensitive fibers respond to?

A

low intensity non-noxious stimuli

prickling, sharp pain

61
Q

Name the origin of the spinothalamic pathway afferent sensory fibers and where they combine to form a single pathway.

A

O: sacral, lumbar, thoracic and cervical spinal cord segments

all sensory afferent fibers combine at C8 to form one pathway

62
Q

Define cingulate

A

unpleasant component of pain

63
Q

Define insula

A

autonomic component of pain response

64
Q

define Amygdala

A

fear and anxiety response to pain

65
Q

What is the tract of lissauer and where is it located?

A

dorsolateral fasciculus

axons branch into ascending and descending collaterals, running up or down 2 spinal segments before penetrating dorsal horn grey matter forming lissauers tract

66
Q

What is the substantia gelatinosa?

A

modulation of nociception and temperature

67
Q

What are the 3 categories of pain?

A

nociceptive

inflamamtory

neuropathic

68
Q

What is the function of substance P?

A

plasma extravasation

histamine release

vasodilation

69
Q

What is the category of pain associated with sensory amplification aiming to protect by producing pain hypersensitivity during healing and is evoked by both high and low intensity stimuli and is not associated with a nervous system lesion?

A

inflammatory

70
Q

What is the category of pain that involves a nervous system lesion or disease and maladaptivr and persistent serving no useful purpose via the transcription of GFs involved in the construction of new synaptic contacts?

A

Neuropathic

71
Q

What is the category of pain associated with no lesion, is envoked by high intensity stimuli only and aims to protect by signalling potential tissue damage?

A

nociceptive.

72
Q

What is central sensitisation?

A

enhancement, potentiation or facilitation of synaptic activity in dorsal horn –>
reduced the threshold of nociceptors
–> early activation 2nd order neurons

73
Q

What is secondary hyperalgesia?

A

allows for a larger number of nociceptors outside the usual range of site damage to reach threshold

74
Q

How is secondary hyperalgesia achieved?

A

2nd order neuron activation: depolarisation

activation of voltage dependent L type Ca channels and
NMDA (Mg removal) receptors –> prolonged depolarization + increased number of receptors available for glutamate and other excitatory neurotransmitters

Elevated Ca –> andenylate cyclase –> cAMP –> protein kinases –> insertion AMPA receptors –> increased sensitivity to glutamate

75
Q

How is pain modulated?

A

activation of inhibitory interneurons

endogenous opioids: enkephalins, endorphins

76
Q

How does enkephalin function?

A

inhibits the release of substnace P

–> inhibits vasodilation, histamine release and angiogenesis.

77
Q

What are the major clinical signs of an animal in pain?

A 
increased BP, HR, adrenaline, sweating
Dilated pupils 
anxiety, fear, aggression : vocalisation, posture
reduced apetite and activity 
response to handling

VET260 (4 decks)

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