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Organ Systems III by Robin > Somatosensation and ascending spinal pathways > Flashcards

Somatosensation and ascending spinal pathways Flashcards

1
Q

Name the three levels of somatosensory integration

A

Somatic sensation, somatic perception, somatic representation

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2
Q

definition: consciousness of stimuli on somatic receptors

A

Somatic Sensation

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3
Q

definition: selection, organization & interpretation of somatic objects& events, + one’s own body, into coherent picture…

A

somatic perception

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4
Q

definition: abstract knowledge, beliefs and attitude about one’s own body

A

somatic representation

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5
Q

Which is not an attribute of sensory systems?

a. intensity
b. temporality
c. adaptation
d. modality
e. localization

A

b. (temporality)

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6
Q

increased stimulus intensity leads to an increase in the frequency of _____

A

AP’s

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7
Q

definition: decrease in neural activity with sustained stimulation

A

sensory adaptation

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8
Q

describe the components of tactile sensation (a sensory modality)

A
  1. touch – pressure, vibration, texture
  2. pain
  3. temperature
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9
Q

describe the components or proprioception (a sensory modality)

A
  1. joint position
  2. muscle sense
  3. movement
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10
Q

Axon membrane receptors respond to:

a. CT capsules
b. modified epithelial cells
c. hairs
d. membrane of free nerve endings
e. c & d only
f. a, b & c only
g. a, b, c & d

A

g. (all four are mediators)

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11
Q

Sensory receptor proteins are _____. Each responds maximally to _____, and less to ______

A

Transient Receptor (TRP) type ion channels; one stimulus (“adequate stimulus”); others

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12
Q

definition: the energy that elicits the greatest response; determines which neurons will generate perception of the sensory modality

A

Adequate Stimulus

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13
Q

use for measuring conduction velocity?

A

gross distinction of modalities (compound AP’s)

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14
Q

Compound action potentials (graphs): what do the peaks correspond to?

A

the population size of axons with a particular diameter of myelination

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15
Q

Match:

A. A-alpha
B. A-beta
C. A-delta
D. C

with:

  1. fast pain
  2. slow pain
  3. proprioception, motor neuron
  4. light touch
A

A. 3
B. 4
C. 1
D. 2

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16
Q

definition: the area of skin that is innervated by the branches of a single neuron

A

Cutaneous receptive field

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17
Q

Peripheral receptive fields are ______ and ______; proximal receptive fields are _____ and _______.

A

densely innervated, small in area; less innervated, large

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18
Q

What attribute of sensory systems is associated with the cutaneous receptive fields?

A

Localization

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19
Q

The relative size and density of receptive fields enable the CNS to determine three categories of information. Name them

A
  1. identify the location of stimulus on the body
  2. distinguish size and shape of the stimulus
  3. resolve spatial resolution
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20
Q

Several primary receptive fields comprise a ______

A

secondary RF

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21
Q

Secondary RF’s overlap; spinal neurons can discern_____

A

subtle differences among them (think: green barrel of monkeys)

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22
Q

Which is not a submodality of tactile sensation?

a. discriminitive touch
b. non-discriminitive touch
c. temperature
d. pressure
e. pain
f. none of the above

A

d. (pressure)

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23
Q

AMong the discriminative touch mechanoreceptors, which are fast acting and which are slow acting: Merkel cells, Ruffini corpuscles, Meissner corpuscles, Pacinian corpuscles, Hair follicles?

A

Slow: Merkel (SA1) and Ruffini (SA2)
Fast: Meissner, Pacinian, Hair follicle
(note: all five are A-beta)

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24
Q

True or False?

  1. Merkel cells discern skin movement and slip for grip control
  2. Ruffini Corpuscles discern skin stretch and hand shape/ position
  3. Meissner corpuscles discern the motion/ direction of tactile stimuli
  4. Pacinian corpuscles discern vibratory stimuli via hand-held objects
  5. Hair follicles discern form and texture when fingers scan a surface
A
  1. F (Merkel = form & texture)
  2. T
  3. F (Meissner = movement, slip/ grip control)
  4. T
  5. F (Hair = motion/ direction)
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25
Q

Describe the Merkel cell-neurite complex

A

clusters of Merkel cells in basal epidermis, “synapse” with sensory axon terminals

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26
Q

Describe Ruffini Endings

A

layers of perineural tissue form large, thin, spindle-shaped cylinders; deep in dermis

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27
Q

What are the make up and location of Meissner corpuscles?

A

lamellar Schwann (tortorus) and CT cells; in dermis just below epidermis

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28
Q

Describe Pacinican corpuscles?

A

lamellar, onion shaped (inner layers = Schwann, outer layers = fibroblasts), encapsulate a single axon; axon ends in dermis of Glabrous (hair-free/ smooth) skin.

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29
Q

Is this the correct mechanism / sequence?
– physical pressure stimulates Pacinian corpuscle -> creates receptor potential -> Glutamate released from axon or lamellar cells -> Glutamate triggers AP

A

Yes, according to Dr. B

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30
Q

What neurotransmitter is involved in Pacinian adaptation, and what is it’s action?

A

GABA inhibits AP’s

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31
Q

True or False? – Merkel and Meissner sensor receptor fields are small and concentrated on the sides of the fingers

A

False – concentrated on fingertips

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32
Q

True or False?

    • Ruffini only detect stretch in specific diretions
    • Pacinian are located along median and ulnar nerves
  • -Ruffini have large receptor fields, but Pacinian have small RF’s
A

False – all true, but both have large RF’s

33
Q

Which types of sensation are associated with free nerve endings, and where are they located?

A

Temperature (within dermis) and pain (epidermis via C and A-delta axons)

34
Q

Which type of pain receptors receive tap, squeeze, rub, skin stretch & non-discriminative touch signals?

A

Mechanoreceptors (SA; A-delta & C)

35
Q

Which type of pain receptors receive hot & cold signals?

A

Thermoreceptors (SA; A-delta & C)

36
Q

Which type of pain receptors receive mechanical or thermal tissue damage signals?

A

mechano-thermal nociceptors (SA; A-delta)

37
Q

Which type of pain receptors receive heat, tissue damage, chemical stimulation (bradykinin, histamine, insect venom) signals?

A

polymodal nociceptors (SA; C)

38
Q

Proprioception involves somatic sensitivity to multiple categories of input: what are they?

A

position, location, orientation, movement – of joints, muscles, fascia

39
Q

Match the receptor(s) with the sensitivity/ -ies:

A. Ruffini
B. Pacinian Corpuscle
C. Muscle spindles
D. Golgi Tendon Organs (GTO’s)

  1. Joint & fascia; CT stretch
  2. Muscle tension
  3. Muscle length
  4. Skin stretch
A

A. 1 & 4
B. 1
C. 3
D. 2

40
Q

Match the receptor with its general sensation:

A. Ruffini
B. Pacinian Corpuscle
C. Free Nerve Endings

  1. Joint position and velocity
  2. Pain sensation/ nociceptor
  3. Pressure
A

A. 1
B. 3
C. 2

41
Q

True or False: GTO’s and Ruffini endings are associated with a slow adaptive response to stretch, while Pacinian corpuscles are associated with rapid adaptation to movement

A

True

42
Q

Match the following to either (A) discriminative touch and proprioception, or (B) non-discriminitive touch, pain, and temperature:

  1. High threshold free nerve endings
  2. Provides qualitative experience of stimulus
  3. Dorsal column/ lemniscal system
  4. Low threshold mechanoreceptors
  5. Rapid AP conduction
  6. Slower AP conduction
  7. Anterolateral system/ spinothalamic
  8. Provides quantitative sense/ localization of the stimulus
A

A. 3, 4, 5, 8

B. 1, 2, 6, 7

43
Q

What is the afferent route of 1st, 2nd and 3rd order neurons in the lemniscal system pathway?

A

spinal cord -> brain stem -> thalamus -> cerebral cortex

44
Q

What type(s) of axons are used by the proprioceptive receptors?

A

Large; A-alpha and Beta

45
Q

Describe 3rd order Thalamic neurons

A

part of internal capsule; project to primary somatosensory cortex (post central gyrus)

46
Q

Describe 2nd order Thalamic neurons

A

decussate in the medulla; axons form medial lemniscus & synapse onto interthalamic neurons

47
Q

Describe 1st order Thalamic neurons

A

sensory axons form cuneate and gracile fasciculi of dorsal columns; axons synapse with neurons in the medulla

48
Q

True or False: Mechanoreceptor axons innervate several segments of the spinal cord before entering the brain stem

A

True

49
Q

True or False: When axons leave a dorsal root, they bifurcate, sprouting multiple collaterals

A

True

50
Q

True or False: one long neuron travels from the Great Toe to the Medulla

A

True!

51
Q

The anterolateral system is less _________, making it slower than the dorsolateral system

A

myelinated

52
Q

The _______ governs responses to stressful situations:

A. VPL nucleus of Thalamus
B. Superior Colliculus
C. Periaqueductal grey matter (PAG)
D. Pontine Reticular Formation

A

C. Periaqueductal grey matter

53
Q

Which of the following is relayed via the anterolateral system?

A. non-discriminitive touch
B. pain
C. Temperature
D. All of the above

A

D. All of the above

54
Q

In the anterolateral system, 2nd order dorsal horn neurons receive messages from 1st order sensory neurons via which neurotransmitters?

A

Substance P, glutamate, NO

55
Q

Sense associated with Rexed’s Lamina I & II?

A

pain

56
Q

Sense associated with Rexed’s Lamina IV?

A

touch

57
Q

2nd order neurons in dorsal horn ________ to the anterolateral system

A

decussate

58
Q

Name the two spinothalamic tracts

A

Neo- and Paleo-

59
Q

Match the neo- and paleo- spinothalamic tracts with their respective regions:

  1. Lateral Thalamus
  2. Medial Thalamus
  3. Cortex
  4. Somatosensory cortex
  5. Reticular formation
A

Neo: 1, 4
Paleo: 2, 3, 5
(I’m not clear on specifics – if any – of 3, this is verbatim from the good Dr.)

60
Q

The anterolateral system has ____ type(s) of 3rd order neurons, which are ________

A

2; lateral thalamic and medial thalamic

61
Q

True or false: Lateral thalamic neurons project to the prefrontal cortex and are somatotopically arranged, with a homunculus for stimulus localization

A

False; the neurons project to the somatosensory cortex. All the rest is true

62
Q

Medial thalamic neurons project to ________ and ______, signalling _______________ of pain, temperature, etc.

A

cingulate gyrus & insula; affective qualities

63
Q

True or false: all medial thalamic neurons generate the experience of dull, persistent pain

A

False: some generate alerting responses to get your attention

64
Q

Where do cysts form in Syringomyelia, and what do they interrupt?

A

in center of cervical grey matter; decussation of 2nd order anterolateral (spinothalamic) neurons

65
Q

True or false: the lesion(s) attendant with Syringomyelia cause bilateral loss of cervicothoracic senses of pain, temperature, discriminitive touch, and proprioception

A

False: discriminitive touch, and proprioception are not affected.
(The loss IS bilateral, and IS localized to the cervical and thoracic regions of the body)

66
Q

The heimsection of Brown-Sequard syndrome refers to a __________cut through dorsal and anterolateral colunms

A

unilateral

67
Q

True or false: Symptoms of Brown-Sequard syndrome include ipsilateral loss of discriminative touch, pain, temperature and motor control

A

False: the loss of pain and temperature sensitivity is CONTRAlateral

68
Q

Why is ipsilateral discriminative touch lost in Brown-Sequard syndrome?

A

Because the sensory neurons cannot decussate at the level of the lesion

69
Q

Why is contralateral pain and temperature sensation lost in Brown-Sequard syndrome?

A

Because the 2nd order neurons decussate below the lesion

70
Q

A dermatome is an area of the skin said to be innervated by one spinal segment. However, dermatomes overlap. Which types of sensation overlap more and which overlap less?

A

More: touch, pressure, vibration
Less: pain, temperature
(Thus we can protect ourselves from the most immediate injuries more immediately, hooray!)

71
Q

Dermatome maps, in spite of their imperfections, are clinically useful to reveal sites of damage to______

A

spinal nerves or the spinal cord

72
Q

Which senses are mediated by the Trigeminal Nerve (choose as many as apply)?

A. Proprioception
B. Discriminitive touch
C. Temperature
D. Pain

A

A, B, C, D

73
Q

Match the Cavity, foramen and dermatome(s) to the correct branch of CN V:

Opthalmic
Maxillary
Mandibular

Nasal cavity
Orbital cavity
Oral cavity

Foramen ovale
Superior orbital fissure
Foramen rotundum

Chin
Side of face
cheek area
dorsum of nose
tympanic membrane
external auditory meatus
forehead
ear
A

Opthalmic: Orbital cavity; Superior orbital fissure; forehead and dorsum of nose

Maxillary: Nasal cavity; Foramen rotundum; cheek area

Mandibular: Oral cavity; Foramen ovale; tympanic membrane, external auditory meatus, Chin, Side of face, ear

74
Q

Name at least three foramina that allow egress of cutaneous branches of the Trigeminal nerve…

A

supraorbital, infraorbital, mental

followed in our notes by “etc.”…

75
Q

How many nuclei does CN V have, and what are their names?

A

Four: Principal (Chief, Main) Sensory nucleus, Spinal Trigeminal nucleus, Mesencephalic nucleus, Motor nucleus

76
Q

which division of CN V innervates the masticators and the soft palate?

A

Mandibular

77
Q

describe the projection of the sensory nuclei of CN V

A

to VPM of thalamus and thence to cerebral cortex

78
Q

Match the nuclei with their sense(s):

Principal (Chief, Main) Sensory nucleus
Spinal Trigeminal nucleus
Mesencephalic nucleus
Motor nucleus

Temperature from face
Motor to Masticating muscles
Muscle reflexes
Discriminative touch from face
Proprioception from masticators
Pain from face
A

Principal (Chief, Main) Sensory nucleus: Discriminative touch from face

Spinal Trigeminal nucleus: Temperature from face, Pain from face

Mesencephalic nucleus: Proprioception from masticators, Muscle reflexes

Motor nucleus: Motor to Masticating muscles

Organ Systems III by Robin (2 decks)

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