ascending tracts Flashcards
(74 cards)
1
Q
- What do sensory nerve fibers in the spinal cord form?
A
Sensory nerve fibers in the spinal cord form bundles or tracts in the white matter.
2
Q
- What are the two types of afferent sensory information?
A
The two types of afferent sensory information are exteroceptive and proprioceptive.
3
Q
- What is exteroceptive sensory information?
A
Exteroceptive sensory information originates outside the body (e.g., pain, temperature, touch).
4
Q
- What is proprioceptive sensory information?
A
Proprioceptive sensory information originates inside the body (e.g., from muscles and joints).
5
Q
- How many neurons typically make up a sensory pathway?
A
A sensory pathway typically involves a three-neuron chain.
6
Q
- Where is the cell body of the first-order neuron located?
A
The first-order neuron’s cell body is in the posterior root ganglion.
7
Q
- Where does the first-order neuron transmit sensory signals?
A
The first-order neuron transmits sensory signals from receptors to the spinal cord.
8
Q
- Where does the second-order neuron project?
A
The second-order neuron’s axon decussates and ascends to the thalamus.
9
Q
- Where does the third-order neuron project?
A
The third-order neuron projects from the thalamus to the cerebral cortex.
10
Q
- What additional structures can sensory pathways connect to?
A
Sensory pathways can connect to the reticular formation and motor neurons.
11
Q
- What is the function of the lateral spinothalamic tract?
A
The lateral spinothalamic tract carries pain and temperature sensation.
12
Q
- What is the function of the anterior spinothalamic tract?
A
The anterior spinothalamic tract carries light touch and pressure.
13
Q
- What are the functions of the posterior white columns?
A
The posterior white columns carry discriminative touch, vibration, and proprioception.
14
Q
- What do the spinocerebellar tracts transmit?
A
The spinocerebellar tracts transmit unconscious proprioception to the cerebellum.
15
Q
- What is the function of the spinotectal tract?
A
The spinotectal tract relays sensory information for spinovisual reflexes.
16
Q
- What is the function of the spinoreticular tract?
A
The spinoreticular tract sends muscle, joint, and skin input to the reticular formation.
17
Q
- What does the spino-olivary tract do?
A
The spino-olivary tract provides indirect afferent input to the cerebellum.
18
Q
- What type of receptors detect pain and temperature?
A
Pain and thermal receptors in the skin use free nerve endings.
19
Q
- What are the two types of fibers carrying pain impulses?
A
Pain impulses travel through fast-conducting Aδ fibers and slow-conducting C fibers.
20
Q
- What type of pain do Aδ fibers transmit?
A
Aδ fibers transmit sharp pain.
21
Q
- What type of pain do C fibers transmit?
A
C fibers transmit burning and aching pain.
22
Q
- Where does pain perception occur?
A
Pain perception occurs in the thalamus and cerebral cortex.
23
Q
- What is the first step in the lateral spinothalamic tract pathway?
A
First-order neurons enter the spinal cord and travel via Lissauer’s tract.
24
Q
- Where do first-order neurons of the lateral spinothalamic tract synapse?
A
First-order neurons synapse in the posterior gray column (substantia gelatinosa).
25
25. What happens to second-order neurons in the lateral spinothalamic tract?
Second-order neuron axons decussate within one spinal segment.
26
26. Where do second-order neurons ascend?
Second-order neurons ascend contralaterally in the lateral spinothalamic tract.
27
27. Where are the third-order neurons of the lateral spinothalamic tract located?
Third-order neurons are located in the ventral posterolateral nucleus of the thalamus.
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28. Where do third-order neurons project?
Third-order neurons project to the somatosensory cortex.
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29. How is fast pain processed in the CNS?
Fast pain travels directly to the thalamus and sensory cortex for precise localization.
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30. How is slow pain processed in the CNS?
Slow pain is relayed through multiple neurons and is poorly localized.
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31. What neurotransmitter is responsible for fast pain transmission?
Glutamate is the fast excitatory neurotransmitter for pain.
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32. What neurotransmitter is involved in slow pain?
Substance P is slowly released and affects multiple neurons in pain transmission.
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33. What is the "winding up" phenomenon?
The "winding up" phenomenon is an increased response to persistent noxious stimuli.
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34. What is the gating theory of pain modulation?
The gating theory states that non-painful stimuli can inhibit pain signals via large myelinated afferents.
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35. How does excessive tactile stimulation affect pain transmission?
Excessive tactile stimulation "closes the gate," preventing pain transmission.
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36. What chemicals help modulate pain in the posterior gray column?
Endorphins and enkephalins help modulate pain in the posterior gray column.
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37. What are the main functions of the ascending tracts?
The ascending tracts relay sensory information such as pain, temperature, touch, vibration, and proprioception to the brain.
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38. How does pain perception involve cognitive and emotional factors?
Pain perception is influenced by emotional and cognitive factors, affecting its intensity and response.
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39. What are the main levels where pain modulation occurs?
Pain modulation occurs at different levels of the nervous system, involving inhibitory mechanisms and neurotransmitters.
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1. What brainstem areas are involved in the analgesia system?
The periventricular area, periaqueductal gray matter, and midline nuclei of the brainstem.
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2. How do fibers from the reticulospinal tract influence pain sensation?
They descend to the spinal cord and synapse on pain-related cells in the posterior gray column, suppressing pain sensations.
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3. What neurotransmitters are involved in the analgesic system?
Enkephalins, endorphins, and serotonin.
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4. How do enkephalins and endorphins modulate pain?
They inhibit substance P release in the posterior gray column.
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5. What is the primary function of the anterior spinothalamic tract?
It carries crude touch and pressure sensations.
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6. Where do first-order neurons of the anterior spinothalamic tract synapse?
In the substantia gelatinosa of the posterior gray column.
46
7. Where do second-order neurons of the anterior spinothalamic tract decussate?
In the anterior gray and white commissures within several spinal segments.
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8. How are fibers arranged in the anterior spinothalamic tract as they ascend?
Sacral fibers are lateral, and cervical fibers are medial.
48
9. Where do third-order neurons of the anterior spinothalamic tract project?
To the somesthetic cortex in the postcentral gyrus of the cerebral cortex.
49
10. What are the two divisions of the posterior white column?
The fasciculus gracilis (lower body) and fasciculus cuneatus (upper body).
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11. Where do first-order neurons of the posterior white column terminate?
In the nuclei gracilis and cuneatus of the medulla oblongata.
51
12. What forms the medial lemniscus?
Axons of second-order neurons after decussating as internal arcuate fibers.
52
13. What sensations are carried by the posterior white column?
Fine touch, two-point discrimination, vibration, and proprioception.
53
14. Where do third-order neurons of the posterior white column pathway project?
To the somesthetic cortex via the internal capsule.
54
15. What is the function of the posterior spinocerebellar tract?
It conveys muscle joint sense from the lower limbs and trunk.
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16. Where does the posterior spinocerebellar tract originate?
From Clarke’s nucleus in the posterior gray column.
56
17. Through which cerebellar peduncle does the posterior spinocerebellar tract enter the cerebellum?
The inferior cerebellar peduncle.
57
18. How does the anterior spinocerebellar tract differ from the posterior spinocerebellar tract?
The anterior tract crosses the midline and ascends contralaterally before re-crossing in the cerebellum.
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19. Through which cerebellar peduncle does the anterior spinocerebellar tract enter?
The superior cerebellar peduncle.
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20. What information does the anterior spinocerebellar tract carry?
Muscle joint information from upper and lower limbs, as well as skin sensations.
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21. What is the function of the cuneocerebellar tract?
It transmits muscle joint sense from the upper limbs.
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22. Where does the cuneocerebellar tract originate?
In the nucleus cuneatus.
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23. What is the destination of the cuneocerebellar tract?
The cerebellum via the inferior cerebellar peduncle.
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24. What is the function of the spinotectal tract?
It is involved in spinovisual reflexes (eye and head movement toward stimuli).
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25. Where does the spinotectal tract synapse?
In the superior colliculus of the midbrain.
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26. What is the function of the spinoreticular tract?
It influences levels of consciousness.
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27. Where does the spinoreticular tract synapse?
In the reticular formation of the medulla, pons, and midbrain.
67
28. What is the function of the spino-olivary tract?
It conveys cutaneous and proprioceptive information to the cerebellum.
68
29. Where does the spino-olivary tract synapse?
In the inferior olivary nuclei of the medulla.
69
30. Where do visceral sensory pathways enter the spinal cord?
Through the posterior roots.
70
31. Where are the first-order neurons of the visceral sensory pathway located?
In the posterior root ganglia.
71
32. Where do second-order neurons of the visceral sensory pathway synapse?
In the posterior or lateral gray columns.
72
33. What tract carries visceral sensory information to the thalamus?
The spinothalamic tract.
73
34. Where is visceral sensory information ultimately processed?
In the postcentral gyrus of the cerebral cortex.
74
35. What is another function of visceral afferent fibers?
Some participate in reflex activity.
