02a: SC Pathways Flashcards
Ascending tracts to cortex typically have (X) number of neurons.
X = 3
Ascending tracts to cerebellum typically have (X) number of neurons.
X = 2
First order neurons for DCML pathway are in:
DRG
DCML carries which (sensory/motor) signals?
Sensory;
- Discriminative touch
- Joint position
- Pressure and vibration
DCML afferent fibers are (myelinated/unmyelinated) and (slow/fast).
(Highly) myelinated; fast
Dorsal column fibers (for DCML path) are arranged into which tracts? Star the most medial tract.
- Fasciculus Gracilis*
2. Fasciculus Cuneatus
Fasciculus gracilis for (X) SC tract fibers is located at which SC levels?
X = DCML (for lower body, below T6)
All SC levels
Fasciculus cuneatus for (X) SC tract fibers is located at which SC levels?
X = DCML (for upper body, T6 and above)
At T6 and above
Posterior intermediate sulcus found at which SC levels? What does it separate?
T6 and above;
Fasciculi gracilis and cuneatus
(X) and (Y), collectively called dorsal column nuclei, are located in:
X = nucleus gracilis Y = nucleus cuneatus
Caudal medulla
Where do first-order DCML fibers synapse?
Dorsal column nuclei (medulla)
Where does the DCML pathway decussate?
Caudal medulla
Following decussation in (X), the DCML (1/2/3)-order neurons form pathway called (Y).
X = caudal medulla
2-order;
Y = medial lemniscus
Axons in medial lemniscus synapse in (X).
X = VPL nucleus of thalamus
DCML third order neurons travel from (X) to (Y).
X = VPL thalamus Y = somatosensory cortex (parietal lobe)
Spinothalamic tract, part of (X) system, carries which (sensory/motor) signals?
X = anterolateral;
Sensory;
Pain and T
Spinothalamic afferent fibers are (myelinated/unmyelinated) and (slow/fast).
Unmyelinated; Slow
First order neurons for ST pathway are in:
DRG
Lissauer’s tract carries (1/2/3)-order neurons from (X) pathway. Projections travel (up/down/across) to (Y).
1st order;
X = ST
Up and down;
Y = 2-3 SC segments rostral and caudal to DRG
Where is Lissauer’s tract located in SC cross-section?
White matter that caps the dorsal horn
Central process of ST tract synapses within (X), aka Rexed’s lamina (Y).
X = substantia gelatinosa Y = 2
Second order neurons of ST tract are located in (X) area and their dendrites extend to (Y) area.
X =
- Nucleus postero-marginalis
- Nucleus propius
Y = substantia gelatinosa
Nucleus postero-marginalis is Rexed’s lamina (X).
X = 1
Post-synpatic processes in substantia gelatinosa belong to (1/2/3)-order neurons for (X) tract.
2nd order;
X = ST
Where do (1/2/3)-order neurons of the ST pathway decussate?
2nd order;
Anterior white commissure (of SC)
Following decussation in (X), the ST (1/2/3)-order neurons form pathway called (Y) that turns (rostrally/caudally).
X = SC
2nd;
Y = spinothalamic;
Rostrally
ST neurons ascend in (X) part of SC to finally synapse onto third order neurons in (Y).
X = anterior portion of lateral funiculus Y = VPL of thalamus
ST third order neurons travel from (X) to (Y).
X = VPL thalamus Y = somatosensory cortex (parietal lobe)
Which paths carry fast versus slow pain? Where are their thalamic nuclei?
Fast: neospinothalamic (VPL)
Slow: Paleospinothalamic (centromedian nucleus)
List the tracts that carry muscle sense information about individual muscles.
- Cuneocerebellar (above C8)
2. Dorsal spinocerebellar (C8 and below)
List the tracts that carry muscle sense information about whole limbs.
- Rostral spinocerebellar (upper limb)
2. Ventral spinocerebellar (lower limb)