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(5) Neurology > (3.2) Ascending Pathways > Flashcards

(3.2) Ascending Pathways Flashcards

1
Q

Which pathways are responsible for conscious sensations?

A
  • Dorsal Column Medial Leminscal (DCML)

- Spinothalamic Pathways

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2
Q

Describe the pathway involved in detecting fine touch from upper and lower limbs.

A

Dorsal Column Medial Meminscal Pathway

  • Cutaneous receptor detects stimuli
  • Synapses 1st order neurone in Dorsal root ganglion
  • 1st order neuron axon ascends in Dorsal horn of spinal cord (if from lower limb, at Fasciculus Gracilis medially, if from upper limb, at Fasciculus Cuneatus laterally)
  • Synapses 2nd order neurone in Medulla (if from lower limb, with Nucleus Gracilis, if from upper limb, with Nucleus Cuneatus)
  • 2nd order neuron axon decussates in Medulla
  • Ascend through Medial Memniscus to synapses with 3rd order neurone in Thalamus
  • 3rd order neuron ascends through Internal Capsule and terminates in somatosensory cortex
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3
Q

Describe the pathway involved in detecting pain from upper and lower limbs.

A

Anterolateral Spinothalamic tracts

  • Nociceptor detects stimuli
  • Synapses 1st order neurone in Dorsal root ganglion
  • 1st order neuron axon ascends one or two spinal levels in spinal cord
  • Synapses 2nd order neurone in Dorsal horn (Substantia Gelatinosa & Nucleus Proprius)
  • 2nd order neuron axon decussates in Spinal Cord and ascend through Ventral White Commissure
  • Synapses with 3rd order neurone in Thalamus
  • 3rd order neuron ascends through Internal Capsule and terminates in somatosensory cortex
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4
Q

Which pathways are responsible for unconscious proprinceptions?

A
  • Anterior Spinocerebellar Tract
  • Posterior Spinocerebellar Tract
  • Cuneocerebellar Tract
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5
Q

Describe the course of the Anterior Spinocerebellar tract.

A
  • Muscle spindle & Golgi tendon detect stimuli
  • Synapses 1st order neurone in Dorsal Root Ganglion
  • 1st order neurone Synapses 2nd order neurone in Spinal grey matter
  • 2nd order neurone decussate and ascends on contralateral side
  • 2nd order neurone through Medulla to Pon and decussates again
  • 2nd order neurone terminates at cerebellum
    e. g. no 3rd order neurone
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6
Q

Describe the presenting symptoms of an injury to the right Lateral Spinothalamic fibres in the dorsal root ganglion at L1 level (hint label a dermatomes map).

A

Loss of pain and thermal sensations at L3 dermatomes of the right side of the body.

https://www.google.co.uk/search?q=dermatomes+map&espv=2&biw=1200&bih=717&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMIv-WU4r-5yAIVxrIUCh10gwPT#imgrc=7FmQKY1ZiLV4nM%3A

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7
Q

Describe the site of lesion if someone presents with loss of pain and thermal sensations on both sides of the body below L2 dermatomes.

A

Lateral Spinothalamic tract fibres in White ventral commisure at T11 vertebra

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8
Q

Describe the presenting symptoms of an injury to the Dorsal Column Medial Lemniscal fibres in the left thalamus (hint label a dermatomes map).

A

Loss of fine touch and conscious proprioceptions of right side of the body, including the face.

https://www.google.co.uk/search?q=dermatomes+map&espv=2&biw=1200&bih=717&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMIv-WU4r-5yAIVxrIUCh10gwPT#imgrc=7FmQKY1ZiLV4nM%3A

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9
Q

Describe the site of lesion if someone presents with loss of fine touches of the right limbs (however, face unaffected).

A

Lesion of Dorsal column fibres at left medial lemniscus from medulla to thalamus

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10
Q

Describe presenting symptoms of an injury to the entire L2 vertebra (hint: shown on a dermatome map).

A
  • Loss of fine touches below L2 on both sides of the body.
  • Loss of pain and thermal sensations below L4 on both sides of the body.

https://www.google.co.uk/search?q=dermatomes+map&espv=2&biw=1200&bih=717&source=lnms&tbm=isch&sa=X&ved=0CAYQ_AUoAWoVChMIv-WU4r-5yAIVxrIUCh10gwPT#imgrc=7FmQKY1ZiLV4nM%3A

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11
Q

A lesion in the thalamus can also lead to a peculiar loss of awareness of the affected side, known as?

A

Ipsilateral agnosia

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12
Q

What is Tabes dorsalis?

A

A late complication of a suphilis infection which results in slow demyelination of the Dorsal Columns of the spinal cord -> loss of discriminative touch and conscious proprioception, hence also ataxia.

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13
Q

What do we mean when we describe a receptor as

  • Tonic
  • Phasic
A
  • Tonic = a very slowly adapting receptor that will respond continuously to the presence of a stimulus and continuous to produce action potential
  • Phasic = a rapidly adapting receptor that will quickly stop responding to a continuous stimulus
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14
Q

What is the role of Thalamus in cutaneous sensations?

A

localise crude touch, pain, thermal sensations

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15
Q

What is Guillan Barre Syndrome?

A

Acute inflammatory demyelinating neuropathy (usually due to an infection) -> paresthesia of hands and feet & loss of tendon reflex & possibly weakness of respiratory muscles

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16
Q

What is Brown-Sequard Syndrome?

A

A hemisection lesion of the spinal cord -> below the lesion:

  • Loss of ipsilateral fine touches & proprioception
  • Loss of contralateral pain & thermal sensations
17
Q

What symptoms may a Syringomyelia cause in terms of cutaneous sensations?

A
  • Compression from cyst of the spinal cord affecting Anterolateral Spinothalamic tract
  • Initially only symptoms of the Cervical and Thoracic outflows (fibres travel medially), as the cyst expands, symptoms progress to Lumbar & Sacral outflows (fibres travel laterally) = Sacral Sparing
  • Loss of pain & thermal sensations
18
Q

List two conditions that only affect the Dorsal Column Medial Lemniscus tract. How do the patients present?

A
  • Vit B12 deficiency -> neurodegeneration
  • Tabes Dorsalis -> late complication of Syphilis infection
  • Loss of fine touch & proprioception (sensory ataxia)
  • Stamping Gait
  • Romberg Sign = unable to stand feet together while eyes closed
19
Q

Describe the site of lesion if someone presents with loss of all sensations on the left side of the body, sparing the face.

A

At pons, affecting both DCML and Spinothlamic tracts on the right side

20
Q

Describe presenting symptoms of an injury to the right Internal Capsule.

A
  • Loss of all sensationes
  • Left side of the body
  • Including the face
21
Q

Define sensory ataxia.

A

movement disorder due to loss of sensory inputs for motor feedback

(5) Neurology (9 decks)

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