Ascending Pathways - SRS Flashcards
Identify the blocked out structures
Starting at 8:00…
Anterolateral System
Ventral Spinocerebellar tract
Dorsal spinocerebral tract
Fasciculus Cuneatus
Fasciculus Gracilis
What three categories of information do spinal cord tracts carry?
- Discriminatory
- Reflexive
- Postural
The spinal cord has tracts that carry discriminatory information which determines type, location and intesity of the stimulus. What are the tracts that carry this?
-
Dorsal columns/medial lemniscus (DCML)
- Fasciculus gracilis
- Fasciculus cuneatus
-
Anterolateral system
- Neospinothalamic
The spinal cord has tracts that carry reflexive information which activates responses to create behavioral state change with appropriate stereotyped motor responses. What are the names of these tracts?
-
Anterolateral system
- Paleospinothalamic
- [spinoreticular]
- [spinomesencephalic]
What senssation types are carried by the discriminatory tracts?
Tactile (temperature, blunt/sharp, locality)
The spine carries postural information regarding joints, tendon and muscle position. What tracts do this?
•Spinocerebellar tracts
–Cuneocerebellar
–[Rostral spinocerebellar]
–Dorsal spinocerebellar
–Ventral spinocerebellar
Fast, wide diameter axons travel to white matter in the?
Posterior funiculi
Slower, thin-diameter axons travel to what structures in the dorsal horn?
Lamina I-VI
How many neurons long are the discriminatory pathways?
3
How many neurons long are postural pathways?
2
What are the types of information in the pathways of the dorsal columns? What are the two portions of this pathway?
Tactile discrimination, conscious proprioception
Posterior columns and medial lemniscus
What are the point of origin receptors for the dorsal columns?
–Meissner’s corpuscles, merkel’s disks, pacinian corpuscles, ruffini’s endings in skin muscle spindles, golgi tendon organs in muscles, joints and tendons
Where are the primary cell bodies of the dorsal columns located?
Dorsal root ganglia (DRG)
Where is the first synapse for the dorsal columns?
–Nucleus cuneatus (for upper body) and nucleus gracilis (for lower body), in caudal medulla
Where do neurons for the dorsal columns enter the spinal cord?
Medial aspect of dorsal horn
Where do discriminatory fiber tracts decussate?
Internal arcuate fibers ventral to cuneatus and gracilis (becomes “medial lemniscus”)
Where is the second synapse of the dorsal columns?
Ventral posteriolateral (VPL) Nucleus of the Thalamus
What is the final destination of the dorsal columns?
Via what structures?
The primary somatosensory cortex (Via internal capsule and corona radiata)
Dermatomes segregate cuneatus from gracilis. What body segments do each represent?
Cuneatus - Thoracic and Cervical
Gracilis - Lumbar and Sacral
What are the nuclei of the Cuneatus and Gracilis seperated by?
Posterior intermediate septum
Identify where the thoracic, sacral, lumbar and cervical tracts are in this spinal segment.
Identify the indicated structures. What portion of the spinal cord is this?
Medulla
Identify the tagged structures. Where is this section from?
Thalamus
Describe the somatotopy of the primary somatosensory cortex.
See attachment
The third pathway takes the anterolateral system. What tract is this?
Neospinothalamic tract
What type of information is conveyed in the neospinothalamic tract?
Pain
Temperature
Poorly localized touch
What are the point of origin receptors involved in the neospinothalamic tract?
Free Nerve endings (TRP channels) in skin, viscera, muscles
Where are the primary cell bodies of the neospinothalamic tract located?
DRG
Where is the first synapse for the neospinothalamic tract?
Lamina I-VI
What is the path into the spinal cord and through it that the neospinothalamic tract takes?
- dorsal horn (Lissauer’s Fassciculus to ascend at least 1 segment)
- after 1st synapse, travels through anterior white commissure
- ascends through anterolateral spinothalamic tract
Where does the neospinothalamic tract fiber decussate?
In the anterior white commissure after the first synapse
Where is the second synapse for the neospinothalamic tract?
Ventral Posteriolateral Nucleus (VPL) of the Thalamus
What is the final destination of the neospinothalamic tract?
–Primary somatosensory cortex (via internal capsule and corona radiata)
Identify the tagged structures
What type of information is carried in the paleoospinothalamic tract?
Poorly localized pain
What is the point of origin receptor for the paleospinothalamic tract?
Free nerve endings (TRP channels) in skin, viscera, muscles
Where are the primary cell bodies of the paleoospinothalamic tract?
DRG
Where is the first synapse for the paleoospinothalamic tract?
Lamina I-VI
Describe the paleospinothalamic tract from the point it enters the spinal column to its ascent.
- dorsal horn (Lissauer’s Fassciculus to ascend at least 1 segment),
- after 1st synapse, travels bilaterally,
- ascends through anterolateral spinothalamic tract
Where does the paleospinothalamic tract decussate?
It doesn’t necessarily, but the fibers that do decussate do so through the anterior white commissure.
Where is the second synapse for the paleoospinothalamic tract?
Intralaminar nuclei of the Thalamus
What is the final destination of the paleoospinothalamic tract?
–Bilateral cortex, poorly localized (includes cingulate gyrus and insula)
Identify the indicated structures
Identify the blocked out labels.
What four tracts make up unconscious proprioception?
- Dorsal spinocerebellar
- Ventral spinocerebellar
- Rostral spinocerebellar (?) (not often in humans)
- Cuneocerebellar
What kind of information do the fifth and 6th pathways carry?
(Dorsal Spinocerebellar and cuneocerebellar)
–Unconscious proprioception
What receptors are involved in the 5th and 6th pathways?
(Dorsal Spinocerebellar and cuneocerebellar)
Muscle spindles and golgi tendon organs in muscles, joints and tendons
Where are the primary cell bodies of the dorsal spinocerebellar and cuneocerebellar pathways located?
DRG
What is the location of the first synapse for the dorsal spinocerebellar and cuneocerebellar tracts?
**Spinocerebellar - **Clarke’s nucleus (AKA nucleus dorsalis) of thoracic cord.
**Cuneocerebellar - ** Accessory cuneate nucleus in the caudal medulla
Where do the 5th and 6th pathways enter/travel in the spinal cord?
Posterior funiculi (hitchhikes with the dorsal columns)
Where do the spinocerebellar and cuneocerebellar pathways decussate?
They do not.
Where is the second synapse for the dorsal spinocerebellar and cuneocerebellar pathways?
–vermis/paravermis of the cerebellum via inferior cerebellar peduncle
What is the final destination of the spinocerebellar and cuneocerebellar tracts?
–Deep cerebellar nuclei (via purkinje cells)
Identify the red circle
When below C8, unconsious proprioceptive information hitchhikes on the posterior column. Where does it synapse? Where is it visible?
–Synapses in Lamina VII
–Visible L3 to C8
•CLARKE’S COLUMN/CLARKE’S NUCLEUS/NUCLEUS DORSALIS
What is the structure circled in red?
Accessory Cuneate nucleus
When above C8, the cuneocerebellar tract synapses in the?
•accessory/external/lateral cuneate nucleus
Identify the indicated structures
Identify indicated structures
Identify indicated structures
What do the ventral spinocerebellar and rostral spinocerebellar pathway carry, information wise?
Broad integrated information from the entire limb
What type of information is carried by the ventral spinocerebellar tract?
–Unconscious proprioception
What are the receptors associated with the ventral spinocerebellar tract?
–muscle spindles, golgi tendon organs in muscles, joints and tendons
Where are the primary cell bodies of the ventral spinocerebellar pathway located?
DRG
Where is the first synapse of the ventral spinocerebellar?
Lamina VII.
Where does the ventral spinocerebellar pathway enter the spinal cord/travel?
Posterior funiculi
Where does the ventral spinocerebellar pathway decussate?
Immediately in the spinal cord
Where is the second synapse for the ventral spinocerebellar pathway? What is unusual about this pathway after the second synapse?
–vermis/paravermis of the cerebellum via superior cerebellar peduncle. Will then decussate again!
What is the final destination of the ventral spinocerebellar tract?
Deep cerebellar nuclei (via purkinje cells)
Identify the indicated structure. What is the spinal section this is from?
Upper Cervical
Patient has a lesion of the right fasciculus cuneatus at C2. Tell me all of the sensory systems affected, and on which side of the body…
- Right-sided, upper-limb tactile discrimination,
- conscious proprioception
- unconscious proprioception of individual muscles/tendons
Patient has a Lesion of Lamina VII in left thoracic spinal cord. Tell me all of the sensory systems affected, and on which side of the body…
•Left sided unconscious proprioception of lower limbs (individual fibers)
Patient has Allodynia (pain due to a stimulus that usually does not provoke pain) on the right side of the leg. Name the possible areas where there might be a lesion…
- Right sided peripheral axons/free nerve endings,
- right sided dorsal horn (Lamina I-V),
- Anterior white commissure,
- Left sided Lateral spinothalamic tract,
- left sided VPL thalamus,
- left sided primary somatosensory cortex
