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Neuro > Ascending Tracts > Flashcards

Ascending Tracts Flashcards

1
Q

Conscious ascending tracts

A

Dorsal column-medial lemniscal
Anterolateral system

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2
Q

Unconscious ascending tracts

A

Spinocerebellar tracts

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3
Q

Function of dorsal column-medial lemniscal pathway

A

Carries fine touch, vibration and proprioception

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4
Q

2 different pathways of dorsal column-medial lemniscal pathway first order neurons

A

Signals from upper limb (T6 and above)
Signals from lower limb (below T6)

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5
Q

dorsal column-medial lemniscal pathway signals from upper limb

A

Travel in fasciculus cuneatus (lateral part of dorsal column)
Synapse in nucleus cuneatus of medulla

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6
Q

dorsal column-medial lemniscal pathway signals from lower limb

A

Travel in fasciculus gracilis (medial part of dorsal column)
Synapse in nucleus gracilis of medulla

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7
Q

Where do the dorsal column-medial lemniscal pathway first order neurons synapse

A

Medulla

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8
Q

Where is the Fasciculus gracilis

A

Medial part of dorsal column

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9
Q

Where is the Fasciculus cuneatus

A

Lateral part of dorsal column

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10
Q

Where do the second order neurones of the dorsal column-medial lemniscal pathway decussate

A

Medulla

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11
Q

dorsal column-medial lemniscal pathway second order neurones

A

Begin in cuneate or gracilis nucleus
Decussate and travel in the contralateral medial lemniscus
Synapse at thalamus

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12
Q

Where do the 2nd order neurons meet the 3rd order neurons of the dorsal column-medial lemniscal pathway

A

Thalamsu

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13
Q

What do the 2nd order neurons of the dorsal column-medial lemniscal pathway travel to the thalamus in

A

Contralateral medial lemniscus

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14
Q

dorsal column-medial lemniscal pathway third order neurons

A

transmit the sensory signals from the thalamus to the ipsilateral primary sensory cortex of the brain
ascend from the ventral posterolateral nucleus of the thalamus, travel through the internal capsule and terminate at the sensory cortex.

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15
Q

Where do the third order neurons of the dorsal column-medial lemniscal pathway terminate

A

Sensory cortex

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16
Q

Where does the third order neurons of the dorsal column-medial lemniscal pathway travel through

A

Ventral posterolateral nucleus of thalamus
Internal capsule
To sensory cortex

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17
Q

2 parts of the Anterolateral system

A

Anterior Spinothalamic tract
Lateral Spinothalamic tract

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18
Q

Function of anterior Spinothalamic tract

A

Crude touch and pressure

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19
Q

Function of lateral Spinothalamic tract

A

Pain and temperature

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20
Q

Anterolateral system first order neurons

A

arise from the sensory receptors in the periphery.
They enter the spinal cord, ascend 1-2 vertebral levels, and synapse at the tip of the dorsal horn – an area known as the substantia gelatinosa.

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21
Q

Where do the Anterolateral pathway first order neurons synapse

A

Substantia gelatinosa (tip of dorsal horn)

22
Q

Where do the second order neurons of the Anterolateral tract decussate

A

Within spinal cord to form 2 tracts

23
Q

Where do the second order neurons of the Anterolateral system synapse

A

Thalamus

24
Q

Anterolateral system third order neurons

A

Thalamus to ipsilateral primary sensory cortex
Ascend from ventral posterolateral nucleus of thalamus, through internal capsule

25
Q

Function of posterior Spinocerebellar tract

A

Carries proprioceptive information form the lower limbs to ipsilateral cerebellum

26
Q

4 individual pathways of Spinocerebellar tract

A

Posterior Spinocerebellar tract
Cuneocerebellar tract
Anterior Spinocerebellar tract
Rostral Spinocerebellar tract

27
Q

Function of Cuneocerebellar tract

A

Proprioceptive information from upper limbs to ipsilateral cerebellum

28
Q

Function of anterior Spinocerebellar tract

A

Proprioceptive information from lower limbs
Decussate twice so terminate in ipsilateral cerebellum

29
Q

Function of rostral Spinocerebellar tract

A

proprioceptive information from the upper limbs to the ipsilateral cerebellum.

30
Q

Which 2 tracts carry proprioceptive information from upper limbs by the Spinocerebellar tracts

A

Cuneocerebellar tracts
Rostral Spinocerebellar tracts

31
Q

Which 2 tracts carry proprioceptive information from lower limbs by Spinocerebellar tracts

A

Posterior Spinocerebellar tracts
Anterior Spinocerebellar tracts

32
Q

Lesions of Spinocerebellar tracts

A

ipsilateral loss of muscle co-ordination.

However, the spinocerebellar pathways are unlikely to be damaged in isolation – there is likely to be additional injury to the descending motor tracts. This will cause muscle weakness or paralysis, and usually masks the loss of muscle co-ordination.

33
Q

Lesion of DCML

A

loss of proprioception and fine touch. However, a small number of tactile fibres travel within the anterolateral system, and so the patient is still able to perform tasks requiring tactile information processing.

If the lesion occurs in the spinal cord (which is most common), the sensory loss will be ipsilateral – decussation occurs in the medulla oblongata.
DCML lesions can be seen in vitamin B12 deficiency and tabes dorsalis (a complication of syphilis).

34
Q

Lesions of Anterolateral system

A

impairment of pain and temperature sensation. In contrast to DCML lesions, this sensory loss will be contralateral (the spinothalamic tracts decussate within the spinal cord).

Brown-Séquard syndrome refers to a hemisection (one sided lesion) of the spinal cord. This is most often due to traumatic injury, and involves both the anterolateral system and the DCML pathway:

DCML pathway – ipsilateral loss of touch, vibration and proprioception.
Anterolateral system – contralateral loss of pain and temperature sensation.
It will also involve the descending motor tracts, causing an ipsilateral hemiparesis.

35
Q

Brown - Séquard syndrome

A

hemisection (one sided lesion) of the spinal cord. This is most often due to traumatic injury, and involves both the anterolateral system and the DCML pathway:

DCML pathway – ipsilateral loss of touch, vibration and proprioception.
Anterolateral system – contralateral loss of pain and temperature sensation.

It will also involve the descending motor tracts, causing an ipsilateral hemiparesis.

36
Q

Sensory modalities

A

Nociceptors
Mechanoreceptors
Thermoreceptors

37
Q

Nociceptors

A

receptors which respond to noxious stimuli (stimuli would result in tissue injury if it were to persist)
• activation results in sensation of pain
• Receptors are free nerve endings on ends of type A-delta fibres and C fibres
• Can be categorised into mechanical, thermal, chemical or Polymodal

38
Q

Mechanoreceptors

A

respond to deformation by means of pressure, touch, vibration or stretch
• located in joint capsules, ligaments, tendons, muscle and skin

39
Q

Types of Mechanoreceptors

A

Merkel’s disc
Meissner’s corpuscles
Pacinian corpuscles
Ruffini corpuscles
Muscle spindles and Golgi tendon organs

40
Q

Merkel’s disc

A

tonic receptors in skin that respond to pressure. Key role in differentiating textures

41
Q

Meissner’s corpuscles

A

phasic receptors in skin, namely in palms of hands, soles of feet, lips and tongue. Detect initial contact or slipping of contact

42
Q

Pacinian corpuscles

A

phasic receptors in dermis, hypodermis, ligaments and external genitalia. Respond to high-frequency vibrations

43
Q

Ruffini corpuscles

A

tonic receptors in dermis, ligaments and tendons. Respond to stretch and signal position and movement of fingers

44
Q

Muscle spindles and Golgi tendon organs

A

found in skeletal muscle and detect stretch as well as involved in proprioception. Transmitted by dorsal column-medial lemniscus pathway

45
Q

Thermoreceptors

A

respond to changes in temperature
• found in skin, liver, skeletal muscle and hypothalamus
• Warm temperatures = C fibres
• Cold temperatures = C and A-delta fibres
• Transmitted via lateral Spinothalamic tract

46
Q

Type of fibres that transmit warm temperatures

A

C fibres

47
Q

Type of fibres that transmit cold temperatures

A

C fibres and A-delta fibres

48
Q

Spinothalamic tract conveys Nociceptive information to….thalamus

A

Contralateral

49
Q

Where in the spinal cord is the spinothalamic tract found

A

Anterolateral white matter

50
Q

A 78-year-old lady presents to her GP surgery with an intensely itchy vesicular rash in two separate horizontal lines at the level of the nipple and umbilicus respectively.

Which dermatomal distribution is this affecting?

A

T4 and T10

Neuro (22 decks)

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