Lecture 7: Sensory Systems 2 Flashcards
Which type of fiber has the fastest conduction speed in spinothalamic pathways
A aloha fibers
Which type of fiber has the slowest conduction speed in spinothalamic pathways
C fibers
Why are C fibers slower than alpha fibers
Not myelinated
In spinothalamic pathways, what are a alpha fibers responsible for (sensation)
Proprioception
In spinothalamic pathways, what a beta fibers responsible for (sensation)
Tough (ex: fine touch, vibration, pressure)
In spinothalamic pathways, what are a delta fibers responsible for (sensation)
Temperature and sharp pain
True of false: a delta fibers are responsible for temperature and dull pain
False, sharp pain
In spinothalamic pathways, what C fibers fibers responsible for (sensation)
Dull pain, temp and itch
Dull pain, temp and itch is associated with what fibers in the spinothalamic pathways
C fibers
Temp and sharp pain is associated with what fibers in the spinothalamic pathways
A delta
Touch is associated with what fibers in the spinothalamic pathways
A beta
Proprioception is associated with what fibers in the spinothalamic pathways
A alpha
True or false, a delta fibers are faster than a alpha
False, they are smaller d slower
Put these in order from slowest to fastest
A alpha
C fibers
A delta
A beta
C fibers
A delta
A beta
A alpha
The anterolateral system is made up of what 2 pathways
Lateral spinothalamic
Anterior spinothalamic
What type of sensation does the lateral spinothalamic pathway caddy
Pain and temperature sensation
What type of sensation does the anterior spinothalamic pathway caddy
Crude touch and pressure sensation
True or false and why: Crude touch and pressure sensation are associated with the lateral spinothalamic pathways
False, with anterior
What are the 3 features of typical sensory pathways (3 neuron rule)
Primary (1o; first order) neuron: cell bodies in dorsal root ganglia
• Secondary (2o; second order) neuron: axons decussate
• Tertiary (3o; third order) neuron: cell bodies in thalamic nuclei
1st order neutrons synapse where with 2nd order neutrons (general)
In brain stem nucleus (NG OR NCH) OR dorsal horn
2nd order neutrons synapse where with 3rd order neutrons (general)
Thalamus (Vpl or Vpm)
2nd order neutrons synapse where with 3rd order neutrons (general)
Primary somatosensory cortex
In the spinothalamic pathways were do primary sensory neutrons enter
The socks enter via the dorsal horn
True or false: like in the DCML pathway, in the spinothalamic pathway, the primary sensory neutrons do not synapse in the dorsal horn
False, in the spinothalamic they do
In the ST TRACT , what happens when primary sensory neutrons axons enter the dorsal horn
They Ascend (or descend) 1–2 spinal segments via posterolateral / dorsolateral (Lissauer’s) tract (black
arrow) à for the
In the ST tract, the primary sensory neutrons They Ascend (or descend) 1–2 spinal segments via what tract
posterolateral / dorsolateral (Lissauer’s) tract
in the ST tract, where do the primary neurons synapse with the secondary neurons
in the nucleus proprius of dorsal horn
where is the in the nucleus proprius located
in the dorsal horn
cells in nucleus proprius have processes that extend into what part
substantia gelatinosa
cells in nucleus proprius have processes that extend into substantia gelatinosa which is important for what modality
pain modulation
true or false, there is decussation in the ST tract at the level of the 1st neuron synapsing with the seconding
true
how do the secondary neurons of the ST trat decussatie
via the anterior white commissure and ascend contralateral spinothalamic tracts
true or false: neurons in the ST tract decussate via the posterior white commissure and ascend contralateral spinothalamic tracts
false, via the anterioe white comisure
explain the somatotropic organization of the spinothalamic tracs
2nd sensory neuron axons from lumbosacral = superficial and lateral
cervical areas=deep medial
where is the spinal leminscus located in relation tothe rostral medulla
dorsal to inferior olivary nuclei and ventral to the inferior cerebellar peduncles
where is the spinal leminscus located in relation tothe pons
along the lateral edge of pontine tegmentum (dorsal to medial lem)
where is the spinal leminscus located in relation tothe midbrain
just dorsal to the medial leminsucs
in the ST tract, after entering the brainstem, the travts formed by secondary sensory neuron axons in the spinothalmic patjways are called what
spinal leminscus
when are the tracts formed by secondary sensory neuron axons in the spinothalmic patjways called spinal leminscus
after entering the brain stem
in the ST tract, where do the sensory neurons synapse with tertiary sesory neurons
in the thalamus (posterior ventral thalamic nuclei)
VPL=body, axial and appendicular
VPM = face (via trigem)
in the ST tract, axons of the tertiary neurons travel through where
internal capsule (posterior limb) and corona radiata before terminating in primary somatosensory cortex
what type of fibers make up the corona radiata
thalamocortical fibers
what is the general process of the spinothalamic pathways
1) primary sensory neuron enters dorsal horn (cell body in dorsalroot gangilon)
=ascends (or descends) 1-2 segments in posterolatral (lissauers tract)
2) synapse with 2 sensory neuron in dorsal horn (nucleus proprious which communicates with substantia gelatinosa)
3) decussation occurs thru anterior white commissure
4) goes up as spinothalamic tract (anterior or lateral = depending on modality)
5) spinal leminstem (in brainstem)
6) synapse with 3 sensory neuron (in VPL of thalamus)
7) interna; capsule (post limb)
8) corona radiata
9) primary sensory cortex (post central gyrus)
What minor pathway brings visceral responses to nociceptibe stimuli
Spinohypothalamic
true or false: spinocerebellar pathways are responsble for non concious sensory pathways
true
how many neurons are involved in the spinocerebellar pathways
only 2 neurons
spinocerebellar pathways carry non concious propriception where
to ipsilateral cerebellum
where do spinocerebellar pathways get their info
from proprioceptors (msucles, tendons,joints) and exteroceptors (cutanrous receptors)
lesions in spinocereballr pathways lead to what
ataxia (loss of muscle coordination)
true or false: spinocerebellar pathways are often damagaed in isolation
false, rarely damaged in isolation from other concious pathways
what are spinal border cells
collection of cell bpdies on dorsolateral aspect of ventral horn (lumbar and cervical regions)
what is nucleus dorsalis
column of stacked nuclei between c8-l2
How many cerebellar pathways are they
4
What type of fibers (general characteristics) would have the fastest conduction speed
Bigger and myelinated
What are some examples of a alpha fibers
Golgi tendons
Muscle spindles
Joint receptors
Why do fibers associated with proprioception need to have fast conduction speed
Need to be able to alter and change body position quickly
Which fibers are important in the DCML
A beta
If you have an initial prick and then a throb, which fibers are associated
A delta (initial prick)
C fibers (dull pain)
What are the two pathways associated with the anterolateral system
Lateral and anterior spinothalamic pathways
Pin prick test tests which pathways
Lateral spinothalamic pathways
What are the 3 key differences between the DCL and spinothalamic
Carries different types of sensory modalities
Location of synapse between primary and secondary (in the brain stem vs the dorsal horn)
Diff location of decussation
free question… good job :) <3
:)
Is the dorsolatefal tract white or grey matter
White
What two structures in the dorsal horn communicate for pain modulation
Nucleus propeius and substantia gelatinosa
In the rostral medulla, is the spinothalamic tract located medially or lateral
Lateral
True or false: the DCML tract and spinothalamic tract have the same blood supply
False, different
What is the tract called before it is called spinal lemniscus
Spinothalamic tract
In the midbrain, does the spinal lemniscus get closer or further from medial leminscus
Closer
What is the function of the spinohypothalamic pathways
Direct visceral responses to nociceptibe stim
What minor pathway is responsible for reflexive head and eye movements in response to stim and pain modulation via periaqueductall grey
Spinomesencephalic/spinotectal
What is the function of spinomesencephalic
Pathways
responsible for reflexive head and eye movements in response to stim and pain modulation via periaqueductall grey
Where does the spinomesencephalic pathway go
Midbrain (and sup colliculi)
What is the function of the spinoreticular pathway
Automatic responses to nociceptive stimuli
(e.g., increase in awareness / arousal) & pain modulation via reticular nuclei
Where does the spinoreticular pathway send info to
Reticular formation
Automatic responses to nociceptive stimuli
(e.g., increase in awareness / arousal) & pain modulation via reticular nuclei
Is what pathway
Spinoreticular
Spinocerebellr pathqays carry non conscious or conciosi proprioception
What are the 3 ways that we get info from the brain stem to cerebellum in spinocerebellar pathways
Superior middle and inferior cerebellar peduncle
Superior cerebellar peduncle is associated with what spinal structure
Midbrain
Middle cerebellar peduncle is associated with what spinal structure
Pons
Inferior cerebellar peduncle is associated with what spinal structure
Medulla
What are the 4 spinocerebellar pathways
Dorsal
Ventral
Rostral
Cuneo
Explain the dorsal spinocerebellar pathway
1o neuron enters dorsal horn
• Synapses with 2o neuron in nucleus dorsalis* à
these nuclei are present from C8–L2 / L3
• Fibers below L2 / L3 will ascend in ipsilateral fasciculus gracilis
• 2o neuron ascends in ipsilateral dorsal spinocerebellar tract
• Enters cerebellum via inferior cerebellar peduncle
(connects medulla oblongata to cerebellum)
• Information from lower limbs
*Nuclei dorsales (plural of nucleus dorsalis) have widespread connectivity & integrate information about the entire lower limb à filter and streamline information being sent to cerebellum; responsible for proprioceptive processing, motor planning, & evaluation
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In the DSCP, where do primary neutrons enter
Dorsal horn
Where do all primary neutrons in the spinocerebellad pathway enter
Thru dorsal horn
Which of the 4 spinocerebellar pathways ascend right after entering the dorsal horn
Cuneo cerebellar
Where does the primary neuron synapse with secondary in the DSCP
in nucleus dorsalis (present from c8-l2,l3)
In the DSCP, fibers below BLANK must ascend in ipsilateral fasciculus gracilis
L2 L3
Explain why in the DSCP, L1L2 must ascend in ipsilateral fasciculus gracilis before synapsing
Because the nucleui dorsali end at l2l3
Where does the secondary neuron ascend in the DSCP
ascend in ipsilateral dorsal spinocerebellar tract
How does info from DSCP enter cerebellum
Via inferior cerebellar peduncle
(connects medulla oblongata to cerebellum)
The DSCP Carries info from what part of the body
Lower limbs
*Nuclei dorsales (plural of nucleus dorsalis) have widespread connectivity & integrate information about the entire upper or lower limb
Lower limb
What is the function of nucleus dorsales
filter and streamline information being sent to cerebellum; responsible for proprioceptive processing, motor planning, & evaluation
True or false: in the DSCP pathway, fibers from below l2l3 must ascend in contralateral fasciculus gracilis
False, ipsilateral
Does the DSCP PATHWAY deccusatw
No
Where does the primary neuron enter in the cuneocerebellar pathway
The dorsal column
True or false and explain, in the Cuneo pathways, the ascends right away
True it enters dorsal horn and ascends in ipsilateral fasciculus cuneatusàjust like in the DCML pathway
Where do the primary neutrons synapse with the secondary neutrons in the Cuneo pathway
In accessory nucleus cuneatus in medulla oblongata
How does info from the Cuneo pathway enter the cerebellum
Enters cerebellum via inferior cerebellar peduncle (connects medulla oblongata to cerebellum)
True or false: both the Cuneo and DSCP pathways enter cerebellum via inferior cerebellar peduncle
True
Which pathway is equivalent to the DSCP but for upper limbs
Cuneo
What structure is functionally analogous to nucleus dorsales by integrating info about the entire upper limb
Accessory nucleus cunnearus
what is the only spinocerebllar pathways that decussates
Ventral spino
Explain the cuneocerebellar (general)
1o neuron enters dorsal horn and ascends in ipsilateral fasciculus cuneatusàjust like in the DCML pathway
• Synapses with 2o neuron in accessory nucleus cuneatus* in medulla oblongata
• Enters cerebellum via inferior cerebellar peduncle (connects medulla oblongata to cerebellum)
• Equivalent to dorsal spinocerebellar pathway, but for upper limbs
*Accessory nucleus cuneatus is functionally analogous to the nuclei dorsales, integrating information about the entire upper limb
15
Explain the ventral spinocerebellar pathwy
1o neuron enters dorsal horn
• Synapses with 2o neuron in lumbar spinal border
cellsàdorsolateral aspect of anterior horn
• 2o neuron decussates in anterior white commissure and ascends in contralateral ventral spinocerebellar tract
• Enters cerebellum via superior cerebellar peduncle (connects midbrain to cerebellum)
• 2o neuron decussates a second time in the white matter of the cerebellum to end up on ipsilateral side (with respect to the 1o neuron)
• Information from lower limbs
What two spinocerebellar pathways carry info from lower limbs
Dorsal spinocereblar
Ventralspimocerebllar
What two spinocerebellar pathways carry info from upper limb
Cuneocerebellar
Rostralspinocerebellar
where does the primary neuron enter for the VSCP
Dorsal horn
Where does the primary neuronvsynapse with the secondary neuron in the VSCP
In lumbar spinal border cells
(Dorsolateral aspdct of anterior horn)
How does info from the VSCP enter cerebellum
Superior cerebellar peduncle
What two pathways use the superior cerebellar peduncle to enter the cerebellum
Ventral spinocerebllar
Rostral spinocerebellar
True or false: only spinocerebellar pathway fhatcdecussates is the RSCP
False
The VSCP
where does the secondary neuron decussate first in the VSCP
anterior white commissure and ascends in contralateral ventral spinocerebellar tract
After the secondary neuron decussates for the first time in the VSCP, how does it ascend
Via contralateral ventral spinocerebllar tract
where does the secondary neuron decussate second in the VSCP
2o neuron decussates a second time in the white matter of the cerebellum to end up on ipsilateral side (with respect to the 1o neuron)
True or false and explain
Because the VSCP pathway decussates in the anterior commissure, it is a contralateral system
False, it decussates a second time so it ends up on ipsilateral side
Does the VSCP carry info from upper or lower limb
Lower limb
Explain the rostral spinocerebllar pathway
• 1o neuron enters dorsal horn
• Synapses with 2o neuron in cervical spinal border
cellsàdorsolateral aspect of anterior horn
• 2o neuron ascends in ipsilateral rostral
spinocerebellar tract
• Enters cerebellum via superior cerebellar peduncle (connects midbrain to cerebellum)
• Equivalent to ventral spinocerebellar pathway, but for upper limbs
In the RSCP, where does the primary neuron enter
Via the dorsal horn
Where does the primary neuron synapse with the secondary neuron in the RSCP PATHW
in cervical spinal border cells
where do secondary neutrons ascend in RSCP
in ipsilateral rostral spinocerebellar rract
How does info from RSCP enter cerebellum
Via superior cerebellar peduncle (connects midbrain to cerebellum)
The rostral is equivalent to what other pathway but for the upper limbs
Ventral
What are the major differences between rostral and ventral spinocerebllar pathways
1) location of secondary synapse (ventral = lumbar spinal border cells since from lower limb, rostral = cervical spinal border cells since upper limb)
2) ventral pathways decussates twice (rostral does not decussate)
3) ventral, Carrie’s info from lower limb while rostral Carrie’s from upper limb
What are the major differences between the dorsal and Cuneo cerebellar pathways
Location of synapse with secondary neuron (dorsal= nucleus dorasalis , Cuneo=accessory nucleus cunearus)
Upper vs lower limbs
