Brainscape's Knowledge GenomeTM

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


See full index

Neuro Exam 2 > 9. Somatosensory: Proprioception/Tactile > Flashcards

9. Somatosensory: Proprioception/Tactile Flashcards

1
Q

what is the role of the somatosensory system?

A

transmit and analyze touch/tactile info from interna/external locations

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

what are the pathways of the somatosensory system

A
  1. posterior column - medial lemniscal pathway
  2. trigeminothalamic pathway
  3. spinocerebellar pathway
  4. anterolateral system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what type of stimuli does the PCMLS percieve

A

mechanical stimuli

discriminative touch, vibration, proprioception on BODY

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

what can the PCMLS discriminate between

A

size, shape & texture

recognize 3D shapes

conscious awareness of body position & limb movement in space

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

what is two point discrimination

A

ability to discriminate btn 2-stimuli

  • varies over diff areas of the body
  • related to density of peripheral N endings
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the receptor density gradients in the the body

A

high density of tactile receptors: digits and oral

low density: other regions like back

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

how is receptive field relate to receptor density

A
  • small receptive field -> high receptor density (small spaces on skin –> need more neurons to cover all these spaces)
  • large field -> low density (largers spaces -> less neurons needed to cover whole body region)

receptive field = skin innervated by somatic afferent fibers

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

what are the properties of primary afferent fibers

A
  • sensory axons w/ cell bodeis in DRG –> enter sp.cord and terminate in grey matter
  • distributed in periphery to form dermatomes (which are associated w fibers/pathways that relay pain/temp info)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what do the large diameter-primary afferent fibers from PCML do

A

relay discriminative touch, flutter/vibration & proprioception

enter sp.cord thru medial division of post root –> branch

—> stay there

or ascend (majority)

or descend

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

where in the spinal cord can a fiber synapse with 2nd order neurons

A

at

above

below levels of entry

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

most of the primary afferent fibers of PCML will enter the spinal cord and do what ….

A

ascend cranially & form posterior column

Post column =

  • fasciculus gracilis (sacral - T6) (LE)
  • fasciculus cuneatus (T6-superior) (UE)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

how are fibers organized in the post column

A

organized topographically

  • sacral level fibers - positioned medially
  • fibers from rostral levels added laterally
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what occurs when there is a lesion in the post. column (sp. cord)

A

ipsilat. reduction/loss of:

discriminative, positional & vibratory/tactile sensation

at or below segments of injury

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

what would happen if you had a tumor in the medial posterior column of the sp. cord?

A

first have LE extremity loss (fasciculus gracile)

then as tumor grows & hits fasciculus cuneatus (lateral part) –> get UE loss

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

what is sensory ataxia

A

neurosyphilis

loss of M stretch reflex

& loss of proprioception from extremites

-may have wide stance, place feet on floor with force

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

what contain the 2nd order neurons of the PCMLS

A

gracile nucleus (sacral -T6)

cuneate nucleus (T6 and above)

get info from primary afferent from ipsilat DRG

17
Q

where do 2nd order neurons in the PCML send info ?

A
  • cross at sensory ducussation = internal arcuate fibers
  • & ascend as medial lemniscus to the thalamus *contralateral*
18
Q

what is the path of medial lemniscus fibers

A

terminate in ventral posterolateral nucleus (VPL) of thalamus

medially = UE fibers

laterally = LE fibers

19
Q

what are the ventral posterior nuclei & what is its blood supply

A

area in caudal thalamas

= ventral posterolateral (VPL) & ventral posteromedial (VPM)

  • VPL - maintain somatotopic arrangement used in PCML path!
  • BS = thalamogeniculate branches of PCA
20
Q

what occurs when thre is a lesion of the thalamogeniculate branches of PCA

A

loss of all tactile sensation over contralat body/head (depending on if VPL or VPM)

21
Q

where do 3rd order neurons start and end

A

start: VPL or VPM

thru post limb of internal capsule

send S1 or S2

22
Q

what is S1 & what is it made of

A

primary somatosensory cortex

-postcentral gyrus & post. paracentral gyrus

BS = ACA & MCA

23
Q

what are brodmann’s areas

A

subdivisions of S1

= Brodmann areas 3a, 3b, 1 & 2

= specific dedicated fxns for higher order processing

24
Q

how would lesions of ACA & MCA affect the primary motor cortex

A

ACA: contralateral lower limb

MCA: tactile loss - contralat upper body/face

(contralat bc crossed medulla - any lesion at or above medulla in this path = contralat damage)

25
Q

what is SII?

A

inner face of upper bank of lateral sulcus (next to insula)

-input from ipsilateral SI corex & ventral post inf nucleus of thalamus

deficit = mimic sensory loss but experience other symps too

26
Q

what will happen if parietal association areas are lesioned

A

Agnosia

contralat body part losses tactile input

limb isnt recognized as own

sensation - not completely lost

27
Q

which nucleus do primary afferents conveying proprioception from TMJ, masticatory & extraocular come from

A

mesencephalic nucleus

28
Q

what does the trigeminal N do

A

distribution from trigeminal ganglion

  • branches= opthalmic, maxillary & mandibular branch
  • pain, temp & nondiscriminative touch
  • discriminative touch (these included bc CN 7, 9, 10 travel with & percieve info)
29
Q

what nuclei from an elongated but continous column

A

(extend from rostral midbrain to spinomedullary jxn)

  1. mesencephalic nucleus- TMJ, masticatory & extraocular (at midbrain)
  2. principal/chief sensory nucleus: discriminative touch & pressure (at midpons)
  3. trigeminal motor nucleus: (at midpons)
  4. spinal nucleus: pain, temp & nondescrim (at obex- C2/3)
30
Q

what/where does principal sensory nucleus send info

A

primary afferents w/ discriminative tactile & proprioceptive sensation

dorsomedial division = oral cavity

ventrolateral division: V1, V2, V3

cross and send to VPM

31
Q

where do fibers project after the principal sensory nucleus

A

ventrolateral: contralat - via anterior trigeminothalamic tract (V1,V2,V3 info)
dorsomedial: ipsilat via post trigeminothalamic tract (oral cavity info)

to the VPM

32
Q

what is the mesencephalic nucleus

A

made of pseudounipolar neurons

  • convey unconscious prorpioceptive & pressure info from Ms of oral region & extraocular Ms
  • project to principal sensory nucleus & spinal nucleus
  • involved in jaw-jerk reflex
33
Q

what is the jaw-jerk reflex

A

stretch massester (tap down on chin) –> contracts bilaterally

afferent limb = mesencephalic trigemnal neuron innervate massester M. spindle & synapse on trigeminal MN (efferent limb)

-reflex enhanced with UMN damage (hyperreflexia)

34
Q

what is the BS for mesencephalic & trigeminal, principal sensory nuclei

A

mesencephalic nucleus/tract: long circumferential branches of basilar A & branches of sup. cerebellar A

Trigeminal Nuclei (mesencephalic, motor & principal sensory) = long circumferential branches of basilar A & AICA branches

Neuro Exam 2 (23 decks)

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