Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Semester 2 Year 1 > Ascending Neural Pathways > Flashcards

Ascending Neural Pathways Flashcards

1
Q

Describe the neural pathway pattern of the somatosensory system that most conscious sensory tracts follow?

A

Primary afferent is a first order neuron and terminates in spinal cord or brain stem

The second order neuron projects to the thalamus

The third order neuron projects to the brain (somatosensory cortex)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the sensation of light touch

A

Awareness of precise location of very delicate mechanical stimuli
- Stroking hairs on skin or feather on hairless skin.

Other phenomena: two-point sense, stereognosis and graphesthesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the sensation of pressure

A

Stimuli applied to subcutaneous structures.

Squeezing muscles or structures under the skin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the sensation of vibration sense

A

Flutter sensation through intact tissues

Can be elicited by placing a tuning fork on tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the sensation of proprioception

A

Motion sense, position sense

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the sensation of pain and temp

A

Nociception (fast and slow)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What the fuck is nociception?

A

The sensory nervous system’s process of encoding noxious stimuli. In nociception, intense chemical (e.g., cayenne powder), mechanical (e.g., cutting, crushing), or thermal (heat and cold) stimulation of sensory nerve cells called nociceptors produces a signal that travels along a chain of nerve fibers via the spinal cord to the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are some nonencapsulated peripheral receptors?

A

Free nerve endings

Merkel discs

Hair follicle receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are some encapsulated peripheral receptors?

A 
Meissner's corpuscles 
Pacinian corpuscles 
Ruffini corpuscles 
Neuromuscular spindles 
Neurotendinous spindles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Where are free nerve endings found?

A

Epidermis, cornea, gut, dermis, ligaments, joint capsules, bone, dental pulp, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where are Merkel discs found?

A

The German Chancellory

Hairless skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where are hair follicle receptors found?

A

Hairy skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Where are Meissner’s corpuscles found?

A

Dermal papillae of skin and palm and sole of foot

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where are Pacinian corpuscles found?

A

Dermis, ligaments, joint capsules, peritoneum, external genitallia, etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where are Ruffini corpuscles found?

A

Dermis of hairy skin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where are neuromuscular spindles found?

A

Skeletal muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where are neurotendenous spindles found?

A

Tendons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the stimulus, sensory modality, adaptability and fibres of free nerve endings?

A

Mechanoreceptor

Pain(fast)
Pain(slow)
Touch(crude)
Pressure,?
Heat and cold

Rapid

A delta,
C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the stimulus, sensory modality, adaptability and fibres of Merkel discs?

A

Mechanoreceptor

Touch

Slow

A beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the stimulus, sensory modality, adaptability and fibres of hair follicle receptors?

A

Mechanoreceptor

Touch

Rapid

A beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the stimulus, sensory modality, adaptability and fibres of Meissner’s corpuscles?

A

Mechanoreceptor

Touch

Rapid

A beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the stimulus, sensory modality, adaptability and fibres of Pacinian corpuscles?

A

Mechanoreceptor

Vibration

Rapid

A beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the stimulus, sensory modality, adaptability and fibres of Ruffini corpuscles?

A

Mechanoreceptor

Stretch

Slow

A beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the stimulus, sensory modality, adaptability and fibres of Neuromuscular spindles?

A

Mechanoreceptor

Stretch - muscle length

Fast

A alpha,
A beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the stimulus, sensory modality, adaptability and fibres of Neurotendinous spindles?

A

Mechanoreceptor

Compression - muscle tension

Fast

A alpha

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the different structural sections of the spinal cord?

A 
Upper cervical
Lower cervical
Thoracic 
Lumbar
Sacral
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is white matter?

A

Axons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What neurons make up the ventral roots?

A

Motor

29
Q

What neurons make up the dorsal roots?

A

Sensory

30
Q

What neurons make up the spinal nerve?

A

mixed sensory/motor

31
Q

What is grey matter?

A

Cell bodies

32
Q

Describe the layout of grey/white matter in the spinal cord?

A

Grey matter forms a “butterfly” in a cylinder of white matter

33
Q

Where are the descending tracts of neurons in the spinal cord?

A

In a triangle that fills all but the most distal space between the dorsal grey horn and ventral grey horn as well as distinct areas in the distal border of the spinal cord ventral to the grey matter.

34
Q

What neurons are in the descending tract?

A

Motor

35
Q

What neurons are in the amending tract?

A

Sensory

36
Q

Where are the ascending tracts of neurons in the spinal cord?

A

All the area posterior to the grey matter medial to the bilateral extensions that make up the dorsal grey horn

The most distal and ventral aspects of the “triangle” of white matter between the dorsal and ventral grey root.
Also the lateral peripheries of white matter between the ventral grey horn and the lateral border of the spinal cord

37
Q

Where in the brain does all this sensory information go?

A

Sensory information passes from the thalamus to the primary somatosensory cortex a region posterior to the central sulcus of the cerebral hemisphere.
Sensory information is somatotopically organized in this region of the cerebrum.
- Unequal distribution of the neural input which is representated by the sensory homunculus.

38
Q

What is the order of the structures commanded in the primary motor cortex from the deepest part of the corpus callosum to the lateral sulcus?

A 
Genitals
Toes
Foot
Leg
Hip
Trunk
Neck
Head
Shoulder
Arm
Elbow
Forearm
Wrist
Hand
Little finger
Ring finger
Middle finger 
Index finger
Thumb
Eye
Nose
Face
Upper lip
Lips
Lower lip
Teeth, gums and jaw
Tongue
Pharynx
Intra-abdominal
39
Q

Describe somatosensory areas I and II

A

Is a distinct and separate spatial organisation in each area.
Area I much more extensive.
”Primary somatosensory cortex” almost always means area I.

Area I: Has a high degree of localisation of different body parts: see names in one of these flashcards somewhere
Area II: poor localisation.

40
Q

what are the ascending pathways?

A

Dorsal column-medial lemniscus pathway

Anterolateral spinothalamic pathway

Dorsal and ventral spinocerebellar tracts

41
Q

Describe the dorsal column-medial lemniscus pathway

A

This pathway allows the perception of:

Well localised touch sensations
Fine gradation of touch intensity
Vibration sense
Proprioception

via large myelinated axon with a velocity of ~30-110m/s to the brain.

42
Q

Describe the first section of the dorsal column-medial lemniscus pathway

A

(1) First order axons enter the dorsal grey horn of spinal cord via dorsal roots

(2) Pass to either cuneate and gracile fasciculus
Above T6 enter fasciculus cuneatus (3b)
Below T6 enter fasciculus gracilis (3a)

43
Q

What structural changes occur when axons in the dorsal column ascend?

A

New fibres are added to its lateral side. Therefore, axons from the cervical region lie lateral those of the sacral region

44
Q

Describe the second part of the dorsal column-medial lemniscus pathway

A

(3) Synapse with second order neuron in either nucleus cuneatus or nucleus gracilis, respectively.
(4) Fibres then decussate via internal arcuate fibres to enter the medial lemniscus

45
Q

Describe the third part of the dorsal column-medial lemniscus pathway

A

(5) Fibres of medial lemniscus ascend and synapse with third-order neurons of the ventral posterolateral (VPL) nucleus of the thalamus.
(6) The third order neurons leave the VPL passing through the internal capsule to terminate in the primary somatosensory cortex.

46
Q

Describe the full progression of the dorsal column-medial lemniscus pathway

A

(1) First order axons enter the dorsal grey horn of spinal cord via dorsal roots

(2) Pass to either cuneate and gracile fasciculus
Above T6 enter fasciculus cuneatus (3b)
Below T6 enter fasciculus gracilis (3a)

(3) Synapse with second order neuron in either nucleus cuneatus or nucleus gracilis, respectively.
(4) Fibres then decussate via internal arcuate fibres to enter the medial lemniscus
(5) Fibres of medial lemniscus ascend and synapse with third-order neurons of the ventral posterolateral (VPL) nucleus of the thalamus.
(6) The third order neurons leave the VPL passing through the internal capsule to terminate in the primary somatosensory cortex.

47
Q

Describe the anterolateral spinothalamic system

A

This pathway allows the perception of:
Poor localisation of touch sensations (crude touch)
Fast and slow pain
Temperature

Via small diameter myelinated and unmyelinated neurons, with lower velocities when compared to dorsal column-medial lemniscus pathway, up to 40m/s.

i.e., the anterolateral system is a cruder type of transmission system than dorsal column–medial lemniscal system. BUT certain modalities of sensation are transmitted only in this system ie pain, temperature, tickle, itch, and sexual sensations (in addition to crude touch and pressure).

Transmission of “less critical” sensory signals

48
Q

Describe the first part of the anterolateral spinothalamic pathway

A

(1) First order axons enter the dorsal grey horn of the spinal cord via dorsal roots.
(2) Enter Lissauer’s tract to ascend or descend 1-2 spinal cord levels.
(3) Synapse in either lamina 1, 2 (substantia gelatinosa) or 5 of the dorsal grey horn.

49
Q

Describe the second part of the anterolateral spinothalamic pathway

A

(4) Decussate via the anterior white commissure to enter the contralateral anterolateral spinothalamic tract.
- It can take 2-3 segments to reach the contralateral side.

50
Q

What information is passed along the anterior spinothalamic tract

A

Crude touch and pressure

51
Q

What information is passed along the lateral spinothalamic tract

A

(pain and temperature)

As this tract ascends, new fibres from higher levels are added to its medial side.

52
Q

Describe the third part of. the anterolateral spinothalamic pathway

A

(5) Ascend to the ventral posterolateral (VPL) nucleus of the thalamus where they synapse with the third order neurons.
(6) The third order neurons leave the VPL passing through the internal capsule to terminate in the primary somatosensory cortex.

Similar to the dorsal column-medial lemniscus pathway

Nerve passes from ventral posterolateral nucleus of the thalamus throughout he internal capsule to brain

53
Q

What is fast pain?

A

Felt within ~ 0.1s after a pain stimulus is applied.
AKA:
sharp pain,
pricking pain,
acute pain,
electric pain.
E.g., When a needle is stuck into the skin, when the skin is cut with a knife, or when the skin is acutely burned. It is also felt when the skin is subjected to electric shock.
Fast-sharp pain is NOT felt in most deep tissues of the body.
Elicited by mechanical and thermal pain

54
Q

What is slow pain?

A

Begins after 1s or more after pain stimulus applied, then increases slowly over 1+s or min.
AKA:
slow burning pain,
aching pain,
throbbing pain,
nauseous pain,
chronic pain.
Is usually associated with tissue destruction.
Can lead to prolonged, almost unbearable suffering.
Slow pain can occur both in the skin and in almost any deep tissue or organ.
Elicited by mechanical, thermal and chemical pain

55
Q

What picks up painful stimuli?

A

All painful stimuli is picked up my nociceptors
free nerve endings in the superficial skin and in some internal tissues (e.g. periosteum, arterial walls, joint surfaces and cranial vault).
Nociceptors show little to no adaptation
But can demonstrate increased sensitivity (hyperalgesia)

56
Q

What are the two pathways for pain transmission into the CNS?

A

Fast-sharp pain pathway

Slow-chronic pain pathway

57
Q

Describe the fast-sharp pain pathway

A

Neospinothalamic Tract

Transmitted via Aδ fibres at ~5-30m/s, mainly mechanical + acute thermal pain.

Terminate mainly in lamina I (lamina marginalis) of the dorsal horns and they excite second order neurons of the neospinothalamic tract.

The second order neurons give rise to long fibres that cross immediately to opposite side of cord through anterior commissure and then turn upward passing to the brain in the anterolateral columns.

58
Q

Describe the slow-chronic pain pathway

A

Paleospinothalamic Pathway (older system)

Mostly transmitted via unmyelinated C fibres at ~0.5-2m/s. Although it does transmit some signals from type Aδ fibres too.

The peripheral fibres terminate in spinal cord almost entirely in laminae II (substantia gelatinosa).

Most signals then pass-through 1 + additional short fibre neurons within dorsal horns before entering (mainly) lamina V.

Then give rise to long axons that mostly join fibres from fast pain pathway, passing first through anterior commissure to the opposite side of the cord, then upward to the brain in the anterolateral pathway.

59
Q

What is referred pain?

A

Pain perceived in a location remote from tissue causing pain.

E.g., pain in a visceral organ referred to an area on body surface.

60
Q

What is the probable mechanism of referred pain?

A

Branches of visceral pain fibres synapse in spinal cord on same 2nd-order neurons that receive signals from skin.
When visceral pain receptors are stimulated, pain signals from viscera are conducted through some of the same neurons conducting pain signals from skin, so person feels sensations originate in skin.

61
Q

Describe the input and basics of the dorsal and ventral spinocerebellar tracts

A

Associated with unconscious proprioception

Gets input from:

  • Muscle Spindles (muscle tension)
  • Golgi organs (proprioception)
  • Touch receptors

Used by the cerebellum to co-ordinate movements and posture

62
Q

Describe the pathway of the dorsal spinocerebellar tract (DSCT)

A

First order axons enter dorsal grey horn via dorsal roots and synapse in Clarke’s nucleus/column.
- Common route for first order neurons of both pathways

Second order axons ascend in the ipsilateral dorsal spinocerebellar tract to the cerebellar cortex.

Conveys input from trunk and lower limbs

63
Q

Describe the pathway of the ventral spinocerebellar tract (VSPT)

A

First order axons enter dorsal grey horn via dorsal roots and synapse in Clarke’s nucleus/column.
Common route for first order neurons of both pathways

Majority second order axons decussate and ascend in the contralateral ventral spinocerebellar tract then crosses back over to the ipsilateral cerebellum.
Minority ascend ipsilaterally to the cerebellum.

Conveys input from trunk, upper limbs and lower limbs.

64
Q

What is anterior spinal cord syndrome?

A

Hyperextension injury
Infarction of anterior spinal artery

Loss of bilateral pain, temp and crude touch below

Maintain bilateral fine touch, vibration and proprioception

65
Q

What is posterior spinal cord syndrome?

A

Penetration injury
Posterior spinal artery occlusion
Multiple sclerosis

Ipsilateral loss of Fine touch, vibration and proprioception

Maintain contralateral Fine touch, vibration and proprioception

Maintain bilateral pain temp and course

66
Q

What is Brown-Séquard syndrome?

A

Penetrating trauma
Same level – ipsilateral total loss of sensation
1-2 levels below – Contralateral loss of pain, temp and course touch
1 level below – ipsilateral loss of fine touch, vibration and proprioception

caused by damage to one half of the spinal cord, i.e. hemisection of the spinal cord resulting in paralysis and loss of proprioception on the same (or ipsilateral) side as the injury or lesion, and loss of pain and temperature sensation on the opposite (or contralateral) side as the lesion

67
Q

What are the important dorsal columns of the ascending tracts?

A 
Gracile fasciculus (3a)
Cuneate fasciculus (3b)
68
Q

What are the important spinocerebellar tracts of the ascending tracts?

A

Posterior (4a)

Anterior (4b)

69
Q

What are the important parts of the anterolateral system of the ascending tracts?

A

Lateral Spinothalamic tract (5a)

Anterior Spinothalamic tract (5b)

Semester 2 Year 1 (82 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions