Brainscape's Knowledge GenomeTM

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


See full index

MBBS II HNNS > L13 - Anatomy of  Somaesthetic Pathway > Flashcards

L13 - Anatomy of  Somaesthetic Pathway Flashcards

1
Q

Classification of sensations?

A

1) Conscious (cerebral cortex, e.g. motor, somatosensory):
a) Exteroception
b) Proprioception

2) Unconscious (e.g. cerebellum; balance):
a) Interoception
b) Proprioception

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

Define exteroception and interoception.

A

Exteroception: sense of direct interaction with the external world as it impacts on the body (e.g. vision, smell)

Interoception: sense of the function of the major organ systems of the body and its internal state

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

Difference in proprioception between conscious and unconscious sensation?

A

Conscious = mediated by dorsal column- medial lemniscal pathway

Unconscious = mediated by spinocerebellar

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

All sensations lead to perception. True or False?

A

False

Depends on whether the sensation is processed by the cerebral cortex

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

Organization of somatosensory system? (3 levels)

A
  1. Receptorlevel: sensoryreceptors
  2. Circuitlevel: processinginascendingpathways
  3. Perceptuallevel: processingincorticalsensory areas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Classify sensory receptors by distribution and by function.

A

Distribution:

1) Exteroceptors @ body surface i.e. free nerve endings
2) Proprioceptors @ muscles, joints, tendons i.e. muscle spindle, joint kinesthetic receptor
3) Interoceptors @ viscera

Function:

1) General sensory (for general senses i.e. temp. pain. vibration…)
2) Special sensory (for special senses i.e. light, taste, sound…)

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

Structure of sensory neurons?

A

Pseudounipolar sensoryneuron:
twofunctionallydistinctsegments,bothfunctionasaxons;

1) oneextendstoperipheralskinormuscle
2) theothertothecentral spinalcord.

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

Relate the type of axons in sensory neurons to the signal transmitted by receptors?

A

Aα = proprioceptors of skeletal muscles

Aβ = Mechanoreceptors of skin

Aδ = Pain, temp

C (unmyelinated) = temp, pain, itch

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

List the major ascending pathways to the brain. Location in spinal cord?

A

1.Spinothalamic(anterolateral)pathway

  1. Dorsalcolumn‐mediallemniscus(posteriorcolumn)pathway
  2. Spinocerebellarpathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Compare the end-points of the 3 major ascending pathways?

A

Dorsal column medial lemniscus + Spinothalamic tract = transmit impulsesviathethalamus tothesensorycortexfor consciousinterpretation.

Spinocerebellar pathway = terminatesinthecerebellum,anddoesnot contributetosensoryperception

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

Compare the sensory information transmitted by the DCML pathway and the Spinothalamic pathway

A

DCML:

  • Discriminative touch / 2-point localization
  • Pressure
  • Vibratory sense
  • Conscious muscle joint sense / position sense (proprioception)

Spinothalamic:

  • Pain, itch
  • Temperature
  • Light/crude (non-discriminative) touch
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Compare the receptors of DCML and spinothalamic tract.

A

DCML:

  • Merkel cells
  • Pacinian corpuscles
  • Muscle spindles
  • Tendon organs

Spinothalamic:
Free nerve endings (e.g. nociceptors)

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

Compare the Dorsal root axon between DCML and spinothalamic tract.

A

DCML = Large diameter myelinated fiber: Aα, Aβ, Aδ

Spinothalamic: Smaller diameter myelinated, unmyelinated fibers: Aδ, C (terminate in dorsal horn)

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

Location of soma, route and end-point of first-order neuron in DCML and spinothalamic pathway.

A

a) cellbodiesresideinaganglion(dorsalrootor cranial)

b) conductimpulsesfromcutaneousreceptors+ proprioceptorstospinalcordorbrainstem (CNS)
»synapsewithsecond‐orderneurons or interneurons in CNS (important for reflex)

c) DCML and spinothalamic 1st order neurons end in spinal cord

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

Location of soma, route and end-point of SECOND- order neuron in DCML and spinothalamic pathway.

A

a) In dorsal horn of spinal cord (spinothalamic)/ brain stem (medulla DCML)
b) Axons decussate (spinothalamic decussate at the level of entry in the spinal cord; DCML decussate in the medulla via Gracile and Cuneate nuclei)
c) Transmit to thalamus (DCML)/ cerebellum (spinothalamic) where they synapse with 3rd order neuron

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

Location of soma, route and end-point of THIRD- order neuron in DCML and spinothalamic pathway.

A

a) In thalamus
b) Carry information to cerebral cortex to synapse with neurons of primary sensory cortex
c) Primary sensory cortex

This does not apply to spinocerebellar pathway

17
Q

The connection between first, second and third order neurons in the somatosensory pathway is always direct. True or False?

A

False

At the two synaptic areas in the CNS, there may be several short interneurons between the axon of the input neuron and the dendrites of the output neuron

18
Q

Summarize the 1st, 2nd, and 3rd order neurons and destination for DCML pathway.

A
  • 1storderneuron:posterior/dorsalroot ganglion ipsilateral
  • 2ndorderneuron:gracilenucleus& cuneatenucleus(decussate inmedulla oblongata midline)&raquo_space;> contralateral medial lemniscus
  • 3rdorderneuron:ventralposterolateral (VPL)nucleusofthethalamus
  • Destination:Primarysomatosensory cortex
19
Q

Difference in function of the 2 nuclei of the second order neruon in DCML?

A

 Cuneate nucleus(more lateral) : arm, upper body

 Gracile nucleus (more medial): leg, lower body

20
Q

Summarize the 1st, 2nd, and 3rd order neurons and destination for spinothalamic pathway.

A
  • 1st order = dorsal horn ganglion
  • 2nd order = dorsal horn of grey matter of spinal cord decussate at level of entry across the midline via ANTERIOR WHITE COMMISSURE
  • 3rd order = :ventral posterolateral(VPL)nucleusofthe thalamus
  • Destination:Primarysomatosensory cortex
21
Q

Compare the tracts that form the DCML and spinothalamic tract?

A

DCML = paired tractsofthedorsalwhitecolumnofthe spinalcord—cuneatefasciculusand gracilefasciculus—andthemedial lemniscus.

Spinothalamic = lateral andanteriorspinothalamictracts

22
Q

Compare the decussation points between DCML and spinothalamic pathways.

A

DCML = Gracile/ Cuneate nuclei&raquo_space; contralateral medial lemniscus across midline of medulla oblongata

Spinothalamic = Anterior white commissure of spinal cord&raquo_space; contralateral spinothalamic tracts

23
Q

Compare the bifurcation of DCML and spinothalamic pathways’ second order neurons.

A

DCML = Bifurcate after entering medial root; large fibers ascend cranially to Gracile and Cuneate fasciculus, small fibers terminate within the spinal cord for reflex

Spinothalamic = Bifurcate into rostral and caudal branches after entering medial root of spinal cord

24
Q

Spinocerebellar tract requires 3 neurons. True or False?

A

False

Only need 2, unlike DCML and spinothalamic tract

25
Q

Function of spinocerebellar pathway?

A

Conveyinformationfrommuscleortendon stretchtothecerebellum,whichusesthis informationtocoordinateskeletalmuscle activity.

Donotcontributetoconscious sensation

Forunconscious proprioception primarilyterminateintheipsilateralcerebellum (not primary somatosensory cortex)

26
Q

Describe the decussation of the spinocerebellar tracts?

A

Dorsal spinocerebellar tract = Do not decussate

Ventral ‘’ = decussate TWICE

Cuneocerebellar tract = Do not decussate

27
Q

Compare the proprioceptive afferents from the different spinocerebellar tracts.

A
  • Dorsalspinocerebellartract:proprioceptive afferentsfromlowertrunkandlowerlimbs, synapse withClarke’scolumncells
  • Cuneocerebellar tract:upperlimbsandneck proprioceptiveinformation
  • Ventralspinocerebellartract:afferentsfrom lowerlimbsspinalmotorneuronsand interneurons
28
Q

Which cranial nerves have somatosensory components?

A

CN 5,7,9,10

Trigeminal
Facial
Glossopharyngeal
Vagus

29
Q

Describe the 1st, 2nd, 3rd order neuron paths for cranial nerve with somatosensory components.

A

1st = sensorynucleusofthe cranialnerveofthesameside

2nd = some cross(somedonot)tothe oppositesideinthebrainstem andascendtothethalamus.

3rd = (atVPM) ascendstothesomatosensory cortex.

30
Q

Compare the sensory information relayed by cranial nerves with somatosensory components.

A

Trigeminal = Discriminative touch, proprioception (e.g. mastication)

facial (VII), glossopharyngeal (IX), vagus (X) = Pain, temp

31
Q

Compare the location of 2nd order neurons of cranial nerves with somatosensory components.

A

Trigeminal = Anterior and posterior trigeminothalamic tract

VII, IX, X = Caudal > relay through spinal trigeminal tract and nucleus (pars caudalis)

32
Q

Describe the processing of sensory information at the perceptual level of the somatosensory pathways.

A

 Most somatic sensory information is relayed to thalamus for processing (conscious perception)

 Adaptation reduces the amount of information reaching the cerebral cortex

 A small fraction (~1%) of sensory information coming in projects to cerebral cortex&raquo_space; reaches our awareness

33
Q

Compare the results of damage to primary sensory neurons vs thalamic projection neurons in spinal cord / brainstem to third order neurons.

A

Thalamic projection neurons to third order neurons: loss of sensation from body below the level of lesion

Primary sensory neuron: absence of sensation from region of body supplied by those nerves

34
Q

Define dermatome. What forms it?

A
  • area of skin supplied by right and left dorsal roots of a single spinal segment
  • formed by peripheral processes of adjacent spinal nerves overlap
35
Q

What causes Wallenbergsyndrome?

A

Wallenbergsyndrome/ PICAsyndrome/ Lateralmedullary syndrome

Blood clot at posterior inferior cerebellar artery

36
Q

List the 5 nuclei/ tracts affected in wallenberg syndrome and relate to 5 clinical manifestations.

A
  1. Contralaterallossofpainand temperaturesensationfromthe body(spinothalamictract)
  2. Ipsilaterallossofpainand temperaturesensationfromthe face(spinaltrigeminaltractand nucleus)
  3. Vertigoandnystagmus(vestibular nuclei)
  4. Lossoftastefromtheipsilateral halfofthetongue(solitarytract andnucleus)
  5. Hoarsenessanddysphagia, decrease gag reflex (nucleusambiguus orrootsofCN IX,GlossopharyngealandX,Vagus) Specific to PICA
37
Q

List the 6 nuclei/ tracts affected in AICA syndrome and relate to 6 clinical manifestations.

A
  1. Spinal trigeminal nucleus = Loss of pain and temp sensation in ipsilateral face
  2. Vestibular nuclei = vertigo, nausea, vomiting
  3. Cochlear nucleus = ipsilateral hearing impairment specific
  4. Facial nerve = ipsilateral facial paralysis, loss of tast at ant. 2/3 tongue, decrease lacrimation and salivation specific
  5. Inferior cerebellar peduncle = ataxia, dysmetria
  6. Sympathetic fibers = ipsilateral horner
38
Q

Cause of Brown‐Séquard Syndrome and clinical symptoms if i.e. T10 level is affected?

A

Hemisection/damageofthespinalcord.

hemisectionofspinalcordatT10:

Ipsilaterallossofproprioceptivesensation,two‐pointdiscriminationand ipsilateralmotorparalysisbelowtheleveloflesion (DCML)

Contralaterallossofpainandtemperaturesensationsafewlevelsbelowlesion (SPINOTHALAMIC)

MBBS II HNNS (57 decks)

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