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Chika- SF2 > Ascending Pathway-Gondre-Lewis > Flashcards

Ascending Pathway-Gondre-Lewis Flashcards

1
Q

What are examples of conscious proprioception?

A
  • Pain
  • Temperature
  • Discriminative touch
  • Position sense
  • Kinesthesia
  • To the cerebral cortex
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2
Q

What are examples of unconscious proprioception?

A
  • Position sense
  • Kinesthesia
  • To the cerebellum

Cerebellum computes a lot of info and send it to the cortex whe???

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3
Q

Proprioception can be unconscious and conscious

A

In humans, a distinction is made between conscious proprioception and non-conscious proprioception:

Conscious proprioception is communicated by the dorsal column-medial lemniscus pathway to the cerebrum.
Non-conscious proprioception is communicated primarily via the dorsal spinocerebellar tract and ventral spinocerebellar tract to the cerebellum.

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4
Q

Conscious vs Nonconscious

A

Exteroceptive
Proprioceptive

Proprioceptive
Enteroceptive

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5
Q

Dorsal Column Medial lemniscus system

A

based on where they are in the ????

  • Medial Lemniscus is a large ascending bundle of heavily myelinated axons that decussate in the brainstem, specifically in the medulla oblongata.
  • The medial lemniscus is formed by the crossings of the internal arcuate fibers. The internal arcuate fibers are composed of axons of nucleus gracilis and nucleus cuneatus.
  • The axons of the nucleus gracilis and nucleus cuneatus in the medial lemniscus have cell bodies that lie contralaterally.
  • medial lemniscus is part of the dorsal column–medial lemniscus pathway, which ascends from the skin to the thalamus
  • is important for somatosensation from the skin and joints

-therefore, lesion of the medial lemniscus causes an impairment of vibratory and touch-pressure sense.

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6
Q

What are the 3 groups of ascending sensory pathways?

A

Pathway for discriminative touch and kinesthesia

Pathway for pain and temperature

Pathway for nonconscious proprioception

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7
Q

What are the tracts associated with the 3 groups of ascending sensory pathways?

A

discriminative touch and kinesthesia –>Tracts: Dorsal Column/Medial Lemniscus system

pain and temperature
—>Tracts: Spinothalamic, Spinoreticular, Spinomesencephalic

nonconscious proprioception —>Tracts: Spinocerebellar tracts -

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8
Q

What are the types of receptors mediating sensory impulses to the brain?

A
  • free nerve endings
  • Meissner’s corpuscles
  • Merkel’s specialized cell
  • Pacinian corpuscle
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9
Q

Cutaneous and subcutaneous receptors

A

vibration
fine touch
changing touch

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10
Q

Muscle spindles and Golgi tendon organs

A

?????

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11
Q

Receptors

A

Convert stimulus into Signal Transduction
Stimulus generates a receptor potential in receptor membrane
Leads to Action Potential, and Na / K influx/efflux

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12
Q

Type I axons fibers (Aalpha)

A
  • Proprioceptors of skeletal muscle

- heavily myelinated (most fast)

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13
Q

Type II axon fibers (Abeta)

A

Mechanoreceptors of skin

-myelinated

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14
Q

Type III axon fibers (Adelta)

A
  • crude touch
  • travel with pain and temperature fibers
  • lightly myelinated
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15
Q

Type IV axon fibers (C)

A
  • pain and temperature sensations

- unmyelinated (least fast)

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16
Q

Where are the cell bodies of these sensory fibers are located?

A

in the dorsal root ganglia (DRG)

remember sensory neurons are pseudounipolar so they have axons coming from the skin going to DRG then axons going to some other part of brain/SC to be interpreted

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17
Q

SLIDE 10 is the first part of the lecture!!

A

Look at the slide and color coding

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18
Q

Dorsal Column/Medial Lemniscal Pathway

A

Fine Touch System
Discriminative Touch System

  • to discriminate between two separate points of contact on the skin that are very close together
  • provides us with a very finely detailed “tactile map” of the body surface and joint positions.

-they are topographically arranged meaning you somatotopic organization in the spinal cord

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19
Q

Primary sensory neurons

A

(pseudo) unipolar neurons with cell bodies in DRG of the spinal cord, or the trigeminal ganglion of the head.

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20
Q

Second order neurons

A
  • send signals across the midline to the other side of the central nervous system. The crossed axons end in the thalamus
  • the second order relay neurons send an axon across to the other side of the central nervous system. Many of these axons terminate in the central core of the brainstem (the reticular activating system). The remainder of the second order axons end in the thalamus on a third order neuron.
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21
Q

Third order neurons

A
  • in the thalamus
  • finally relay the touch/pressure information to the primary somatosensory cortex
  • Some of the third order axons travel to the cells of the postcentral gyrus.
  • primary somatosensory cortex is located in the postcentral gyrus, and is part of the somatosensory system.
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22
Q

Fine Touch System AKA discriminative touch system

A
  1. Large Ab axons
  2. Ipsilateral dorsal column
  3. Synapse onto ipsilateral dorsal column nuclei in medulla
  4. Decussation occurs at the brainstem
  5. Medial lemniscus (contralateral representation)
  6. Synapse on ventral-posterio-lateral nucleus of THALAMUS
  7. Primary Somatosensory Cortex
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23
Q

dorsolateral
division of root
of spinal cord

A

this is the spinal cord

????

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24
Q

ascending sensory pathways AKA dorsal columns

A

fasciculus cuneatus (more lateral): originates C1-T5

fasciculus gracilis (towards the midline): originates T6-S5; lower limbs

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25
Q

Brainstem

A

lowest level of brainstem is the level of motor decussation; between the SC and brainstem

dorsal column nuclei are located: level of sensory decussation

Open medulla (where you see the 4th ventricle)

Level of mid pons

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26
Q

Brainstem slide 16????

A

dorsal column and after synapsing on the ?????after it decussates it becomes the medial lemniscus

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27
Q

Nucleus cuneatus

A

The accessory cuneate nucleus is located lateral to the cuneate nucleus in the medulla oblongata at the level of the sensory decussation (the crossing fibers of the posterior column/medial lemniscus tract). It receives input from cervical spinal nerves and transmits that information to the cerebellum.

28
Q

nucleus gracilis

A

Located in the medulla oblongata, the gracile nucleus is one of the dorsal column nuclei that participate in the sensation of fine touch and proprioception of the lower body (legs and trunk). It contains second-order neurons of the posterior column-medial lemniscus pathway, which receive inputs from sensory neurons of the dorsal root ganglia and send axons that synapse in the thalamus.

29
Q

Midbrain of Brainstem

A
  • level of inferior colliculus
  • level of superior colliculus
  • level of meso-diencephalic junction
  • level of mid thalamus
30
Q

cell bundles end in the tubercles

A

The neurons contained within the nucleus form a visible bump called the gracile tubercle on the posterior side of the closed medulla at the floor of the fourth ventricle.???

31
Q

Ventral posterior nucleus is the somato-sensory relay nucleus in thalamus of the brain

A

The ventral posterior nucleus is divided into:

Ventral posterolateral nucleus, which receives sensory information from the body.
Ventral posteromedial nucleus, which receives sensory information from the head and face via the trigeminal nerve.
Ventral intermediate nucleus, implicated in oscillatory tremor generation in Parkinson’s disease and essential tremor.[1]

32
Q

lateral fissure (temporal lobe)???
parahippocampal gyrus
slide 21

A

?????

33
Q

The Trigeminal System

A

Information re: touch from the face arises from trigeminal nerve. They synapse onto to the Chief Sensory Nucleus (second order nucleus) of V located in the pons. Then you decussate.

They cross the midline and travel alongside the medial lemniscus, and then terminate on the ventral posterio-medial nucleus of the thalamus (third order neuron).

34
Q

Slide 24 shows pictorial view for the trigeminal system

A 
??????
Trigeminal ganglion (DRG)
dorsal column slide 25

replay what she said

35
Q

first-order neurons vs.
second-order neurons vs.
third-order neurons

A

The first-order neurons carry signals from the periphery to the spinal cord; the second-order neurons carry signals from the spinal cord to the thalamus; and the third-order neurons carry signals from the thalamus to the primary sensory cortex. Second-order neurons are generally located in the spinal cord or brainstem.

36
Q

Decussation typically occurs at what order of neurons?

A

at the second-order neuron

37
Q

Brodmann areas 3, 1, and 2 make up the primary somatosensory cortex of the human brain (or S1).

A

The primary somatosensory cortex is located in the postcentral gyrus, and is part of the somatosensory system

38
Q

To where in the brain/somatosensory/ muscle spindle, joints do mechanoreceptors go?

A

????

39
Q

Coded information from the right hand is traveling along second-order sensory (crossed) neurons in the medial part of the left posterior column-medial lemniscal pathway in the upper brainstem

A

?????

40
Q

areas 5 7 40

A

secondary association areas so we can put in the decoded information

41
Q

clinical neuroanatomy saunders book

A

????slide 30

42
Q

Synapses in the Primary Somatosensory Region

A

Muscle Spindle fibers – Area 3a –> Area 2
Mechanoreceptors – Area 3b –> Area 1 Mechanoreceptors – Area 3b –> Area 2
Golgi Tendon Organs – Area 2
Area 1 —> Area 5, 7, 40
Area 2—>Area 5, 7, 40

43
Q

Spinothalamic tract

A
  • The spinothalamic tract (also known as anterolateral system or the ventrolateral system) is a sensory pathway from the skin to the thalamus.
  • From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory cortex of the postcentral gyrus.

To: Thalamus
Artery: Anterior spinal artery
Part of: Spinal cord
Decussation: Anterior white commissure

44
Q

The Pain/Temperature/Coarse Touch System

A
  • This system carries pain and temperature as well as a kind of tactile information referred to as crude or non-discriminative touch.
  • It is crude touch because if two points of contact on the skin are close together this system registers them as one.
  • There are no known specialized receptors for this system; the free nerve endings of the peripheral axons themselves being sensitive to pain and temperature.
45
Q

Fine touch system vs Pain/Temperature/Coarse Touch System

A

Compared to the Fine Touch System, the cell bodies of these neurons are smaller and the axons are thinner in diameter and are poorly myelinated. Thus, information is not conducted as quickly in this system.

  • The primary sensory neurons are smaller than those of the Fine Touch System, but otherwise the location of their cell bodies and the distribution of their peripheral axons is similar.
  • However, the termination of their central processes differs from the Fine Touch System, ending on cell bodies of second order neurons that are located in the brainstem.
46
Q

Spinothalamic Tract vs dorsal column-medial lemniscus pathway

A
  • In contrast to the axons of second-order neurons in dorsal column-medial lemniscus pathway, the axons of second-order neurons in the spinothalamic tracts cross at every segmental level in the spinal cord. This fact aids in determining whether a lesion is in the brain or the spinal cord.
  • The spinothalamic tract, like the dorsal column-medial lemniscus pathway, uses three neurons to convey sensory information from the periphery to conscious level at the cerebral cortex.

ST Travel alongside medial lemniscus pathway
Remain distinct
ST ascends contralaterally, ML ascends ipsilaterally
** Cold receptors coupled to Ad & C fibers while hot is C only

47
Q

Lesions in brainstem vs spinal cord in reference to sensations

A
  • With lesions in the brain stem or higher, deficits of pain perception, touch sensation, and proprioception are all contralateral to the lesion.
  • With spinal cord lesions, however, the deficit in pain perception is contralateral to the lesion, whereas the other deficits are ipsilateral.
48
Q

Nerves need blood supply!

A

Nerves are bloodthirsty. One potential issue is lack of blood supply. Nerves are incredibly bloodthirsty, and consume 20% of the bodies’ entire oxygen supply even though they comprise only 2% of the body’s weight. Nerves need a continuous supply of blood and begin to lose function rather quickly with oxygen deprivation.

49
Q

Structure of the spinothalamic tract

A
  • Pseudounipolar neurons in the DORSAL ROOT GANGLION have axons that lead from the skin into the dorsal spinal cord where they ascend or descend one or two vertebral levels via Lissauer’s tract and then synapse with secondary neurons in either the SUBSTANTIA GELATINOSA of Rolando or the NUCLEUS PROPRIUS. These secondary neurons are called tract cells.
  • The axons of the tract cells cross over (decussate) to the other side of the spinal cord via the ANTERIOR WHITE COMMISSURE, and to the anterolateral corner of the spinal cord (hence the spinothalamic tract being part of the anterolateral system). Decussation usually occurs 1-2 spinal nerve segments above the point of entry.
  • Axons of 2nd order neurons, decussate & run along the VENTRAL SC to Thalamus
  • The axons travel up the length of the spinal cord into the BRAINSTEM, specifically the rostral ventromedial medulla.

Traveling up the brainstem, the tract moves dorsally. The neurons ultimately synapse with third-order neurons in several nuclei of the thalamus—including the medial dorsal, ventral posterior lateral, and ventral posterior medial nuclei. From there, signals go to the cingulate cortex, the primary somatosensory cortex, and insular cortex respectively.

50
Q

Anterolateral system

A
  • An ascending pathway that conveys pain, temperature (protopathic sensation), and crude touch from the periphery to the brain.
  • comprises three main pathways:

Name—>Destination—>Function
-spinothalamic tract (lateral and anterior)—> thalamus —>important in the localization of painful or thermal stimuli

  • spinoreticular tract —>reticular formation—> causes alertness and arousal in response to painful stimuli
  • spinotectal tract—>tectum—>orients the eyes and head towards the stimuli
51
Q

Substantia Gelatinosa & Nucleus Proprius receive what kind of fibers?

A

receives pain fibers C, Adelta AKA Type III and Type IV

52
Q

Referred pain

A

Cutaneous & visceral nociception crosstalk greatly ?????

53
Q

lateral spinothalamic tract vs. anterior spinothalamic tract

A

The lateral spinothalamic tract transmits pain and temperature. The anterior spinothalamic tract (or ventral spinothalamic tract) transmits crude touch and firm pressure.

54
Q

white matter= axons= nerves fibers

A

FACTS!

55
Q

Pain/Temperature sensation of face

A
  • The sensory trigeminal nerve nuclei are the largest of the cranial nerve nuclei, and extend through the whole of the midbrain, pons and medulla, and into the high cervical spinal cord.
  • All sensory information from the face, both touch-position and pain-temperature, is sent to the trigeminal nucleus.
  • All sensory fibers from these nerves terminate in the trigeminal nucleus. On entering the brainstem, sensory fibers from V, VII, IX and X are sorted and sent to the trigeminal nucleus (which contains a sensory map of the face and mouth).
  • The spinal counterparts of the trigeminal nucleus (cells in the dorsal horn and dorsal column nuclei of the spinal cord) contain a sensory map of the rest of the body. The trigeminal nucleus extends throughout the brainstem, from the midbrain to the medulla, continuing into the cervical cord (where it merges with the dorsal horn cells of the spinal cord).
  • The spinal trigeminal nucleus represents pain-temperature sensation from the face. Pain-temperature fibers from peripheral nociceptors are carried in cranial nerves V, VII, IX and X. On entering the brainstem, sensory fibers are grouped and sent to the spinal trigeminal nucleus. This bundle of incoming fibers can be identified in cross-sections of the pons and medulla as the spinal tract of the trigeminal nucleus, which parallels the spinal trigeminal nucleus. The spinal tract of V is analogous to, and continuous with, Lissauer’s tract in the spinal cord.
  • The spinal trigeminal nucleus contains a pain-temperature sensory map of the face and mouth. From the spinal trigeminal nucleus, secondary fibers cross the midline and ascend in the trigeminothalamic (quintothalamic) tract to the contralateral thalamus. Pain-temperature fibers are sent to multiple thalamic nuclei. The central processing of pain-temperature information differs from the processing of touch-position information.
  • Spinal Trigeminal Nucleus
  • joins the spinothalamic tract ?????
56
Q

Stopped at slide 45

slide 47 is dorsal column vs spinothalamic

A

???

57
Q

Ascending Tracts

A

Dorsal Column Tract (on back of brainstem)

  • Fasciculus Gracilis (Lower limb)
  • Fasciculus Cuneatus (upper limb)

Dorsal/ Ventral Spinocerebellar Tract

Lateral Spinothalamic Tract (anterolateral system)
Ventral Spinothalamic Tract

58
Q

Dorsal Column Tract

  • Fasciculus Gracilis (Lower limb)
  • Fasciculus Cuneatus (upper limb)
A

conveys information about:

  • fine touch (discriminative touch), pressure, vibration, CONSCIOUS proprioception, and Stereognosis
  • Stereognosis(also known as haptic perception or tactile gnosis) is the ability to perceive and recognize the form of an object in the absence of visual and auditory information, by using tactile information to provide cues from texture, size, spatial properties, and temperature

through fibers that will go through

  • First order neurons in DRG; fibers from here mainly continues as/a small number of fiber will synapse onto to
  • continues as fasciculus gracile and fasciculus cuneatus ; synapse onto neurons in the nucleus proprius that synapse in the ventral horn to maintains the spinal reflex; fasciculus gracile and fasciculus cuneatus synapse onto second order neurons in the
  • nucleus gracile and nucleus cuneatus in the medulla oblongata; fibers from here will decussate to the other side (decussate at the level of medulla oblongata) as internal arcuate fibers to continues the
  • medial lemniscus (has fibers from ventral spinothalamic tract that does crude touch while dorsal column tract does fine touch and pressure; these fibers synapse onto third order neurons in the thalamus with fibers to project to cortex
59
Q

Dorsal/ Ventral Spinocerebellar Tract

A

-for unconscious proprioception from the body EXCEPT from the upper limb
-destination is the cerebellum
-cerebellar peduncles connect the cerebellum to the brainstem
-peduncle is a bundle of white fibers that is communication between two parts of the brain
superior peduncle: midbrain
middle peduncle: pons
inferior peduncle: medulla

  • First order neurons in the DRG send fibers to
  • Nucleus dorsalis or Clarke’s column which then send fibers either to the same side to reach OR cross over to the opposite side and ascend to the

-inferior cerebellar peduncle (dorsal spinocerebellar tract) OR midbrain to go to the superior cerebellar peduncle (ventral spinocerebellar tract)

unconscious proprioception from the the upper limb will go to DRG then to the fasciculus cuneatus to reach the accessory cuneatus nucleus in the medulla oblongata which will go fibers (Cuneocerebellar tract) to the inferior cerebellar peduncle

60
Q

Lateral Spinothalamic Tract

Ventral Spinothalamic Tract

A

Lateral Spinothalamic Tract for pain and temperature

Ventral Spinothalamic Tract for crude touch (non-discriminative touch)
-will join the medial lemniscus

  • First order neurons in DRG and their axons synapse in
  • second order neurons in the substantia gelatinosa in dorsal horn (GRAY MATTER); fibers from here cross to the other side (decussate at the level of spinal cord) forming
  • the lateral and ventral spinothalamic tract which will then form/continue as the
  • spinal lemniscus for lateral ST; ventral ST will join the medial lemniscus; these fibers will synapse on
  • third order neurons in the thalamus and fibers from here will project to the cortex
61
Q

For any tract the first order neurons are from where?

A

DRG

62
Q

All lemniscus are formed on what side? Any injury to any lemniscus the effect has to be?

A

All lemniscus are formed on the CONTRALATERAL side; they only form after decussation

Any injury to any lemniscus the effect has to be CONTRALATERAL.

63
Q

lateral lemniscus to the medial geniculate nucleus auditory relay

A

?????

64
Q

In case of the dorsal column tract:

Any injury to fasciculus gracile/cuneatus will be on what side? What about injury to the medial lemniscus?

A

injury to fasciculus gracile/cuneatus: IPSILATERAL loss of conscious proprioception

injury to the medial lemniscus: CONTRALATERAL

65
Q

What is the highest center for pain?

A
  • thalamus

- cortex does not have centers for pain

Chika- SF2 (63 decks)

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