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Exam Two - DCML Flashcards

1
Q

DCML

A

dorsal column medial lemniscus

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2
Q

What is the overall purpose of the DCML system?

A

discriminative touch and conscious proprioception

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3
Q

What are the 5 general structural components of the somatosensory system?

A
  • in the PNS
    1 - peripheral receptory
    2 - primary afferent fibers and their ganglia
  • in the CNS
    3 - a decussation
    4 - a thalamic relay nucleus
    5 - a cortical projection target
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4
Q

What are the key steps in sensory transduction?

A
  • sensory receptor (adequate specific stimulus)
  • membrane conductance changes
  • generator potentials
  • action potentials
  • primary afferent signals
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5
Q

4 ways to code sensory information?

A

modality
intensity
duration
location

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6
Q

receptive field

A

the space where the receptor is located and transduce the stimuli
small receptive fields increase the likelihood of discrimination

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7
Q

GSA

A

general somatic afferents
receptors are mainly located in body/soma wall (skin, muscle, joints, periosteum, and associated structures)

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8
Q

GVA

A

general visceral afferent
located within or near visceral organs

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9
Q

SSA

A

special somatic afferents
vision and hearing

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10
Q

SVA

A

special visceral afferents
smell and taste

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11
Q

What are the 3 classifications of somatosensory receptors?

A

mechanoreceptors
thermoreceptors
nociceptors

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12
Q

proprioception

A
  • awareness of the body position and movement
  • dynamic 3D mental construct of the body generated by integrative activity occurring the the parietal lobe
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13
Q

What 3 systems provide integrate to form proprioception

A
  • vestibular
  • visual
  • somatosensory
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14
Q

What are the 4 main somatosensory proprioceptors

A
  • cutaneous mechanoreceptors
  • muscle spindles
  • golgi tendon length
  • mechanoreceptors in joints
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15
Q

What are the 4 main functions of peripheral receptors functions?

A

1 - general arousing and alerting (consciousness)
2 - conscious discrimination of environmental events by acting on neurons of the cerebral cortex via ascending systems
3 - to elicit reflexes
4 - enabling coordinated movements by acting on neurons belonging to the motor control system

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16
Q

What systems are included in GSA conscious classification?

A

-DCML
-ALS
- cranial nerves 5, 7, 9, 10

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17
Q

What systems are included in GSA unconscious classification

A
  • spinal cord and brains tem reflex connections
  • dorsal spinocerebellar tract
  • ventral spinocerebellar tract
  • cuneocerebellar tract
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18
Q

How many neurons are involved in the DCML pathway?

A

3 projection neurons, 1st, 2nd, 3rd order neruons

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19
Q

Where is the 1st order neurons’s soma for DCML?

20
Q

How does the 1st order neuron for DCML enter the CNS?

A

via the dorsal root without synapsing!

21
Q

Do first order or second order neurons cross in the DCML system?

A

second order, 1st order neurons project ipsilaterally to the second order neurons

22
Q

Where are the second order neurons located in the DCML system?

A

nucleus gracilis(Lower Extremity) and nucleus cuneatus(Upper Extremity) in the medulla

23
Q

Where do second order neurons terminate in the DCML system?

A

2nd order neurons cross the midline (forming the medial lemniscus) and ascend to the thalamus to terminate of 3rd order neurons

24
Q

How do 3rd order neurons of the DCML project to the cerebral cortex?

A

the posterior limb of the internal capsule

25
Where specifically do 3rd order neurons of the DCML terminate in on the cerebral cortex?
the primary somatosensory cortex (areas 3, 1,2) of the post-central gyrus
26
What specific part of the thalamus do 2nd order neurons synapse with?
VPL
27
What is the orientation of the ML at the medulla
A T L
28
What is the orientation of the ML at the middle to rostral pontine level?
L T A
29
What is the somatotopic organization of the thalamus?
foot = lateral hand = medial
30
What is the somatotopic organization of the priamry somatosensory cortex (SI)
foot = medial hand (and face) = lateral
31
site 3 of SI receives:
most thalamic input, site of initial processing
32
site 3b receives?
touch (cutaneous, SA)
33
site 3a receives?
proprioception (deep, muscle)
34
sites 1 and 2 of SI receive?
they are connected to 3b, sites of complex processing 1 = cutaneous RA 2 = deep, joint
35
sensory homunculus
- not body proportional - not a "single" map - FOOT MEDIAL AND FACE LATERAL
36
Role of SII?
- performs higher order functions - association area for sensory input - ROLE IN EPISODIC MEMORY, VISUOSPATIAL PROCESSING, CONSCIOUSNESS AND HIGH ORDER FUNCTIONS, SUCH AS SELF-REFLECTION - connected to the limbic system
37
Where is SII located?
parietal operculum
38
What is the parietal operculum?
the part of the parietal lobe that overlies the caudal portion of the insula in primates. It is defined by dissection
39
Purpose of brodmann areas 5 and 7?
- association cortex for somesthesis - INTERPRET MEANING OF INPUT
40
somesthesis
body sensibility including the cutaneous and kinesthetic senses
41
What can damage of brodmann areas 5 and 7 produce?
hemi-neglet syndrome (amorphosynthesis) - the patient is unaware of somatic sensations from one side of the body
42
functional properties of the DCML
- receives input via large diameter myelinated axons - highly topographic at all levels - RF size small - submodality purity at all levels - secure relays (a single AP can prudce a perception)
43
describe organization of DCML at the SC, thalamus, and SI cortex
SC: food medial, hand lat thalamus: foot lateral, hand/face medial SI cortex: foot medial, hand/face lateral
44
lesions at the DCML
- increase in the two point threshold - decrease in vibratory sensitivity - decrease in position sense and kinesthesia - agraphesthesia - astereognosis - increase in spontaneous pain
45
kinesthesia
awareness of movement of the parts of the body
46
agraphesthesia
impaired ability to recognize letters or numbers drawn by an examiners fingertip on the patients skin (with patients eyes closed)
47
astereognosis
inability to identify a common object by active touch without other sensory input such as visual information

Neuroscience (25 decks)

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