lec 3 Flashcards
Ascending tracts of white matter (sensory) includes 3 main groups
lemniscal system
Unconcious proprioceptive tracts (to cerebellum)
anterolateral system
Lemniscal system: lie in the ———– carries ———– from——————– to the ————— formed of :
dorsal column
conscious proprioception
deep structures such as muscles & joints
cerebral cortex
1. Gracile tract[lower body proprioception]
2. Cuneate tract [upper body proprioception]
which structures relays conscious proprioception ? and unconcise proprioception (nucleus and tracts) ? exteroception (nucleus and tract) ?
lemniscale system
- Nucleus Dorsalis “Clarke‟s Nucleus” + Unconcious - - proprioceptive tracts:
1. Two spino-cerebellar tracts (Post. & Ant.).
2. Spino-olivary tract. - supstantia gelatinosa of rolandi
- Nucleus Proprius (Main sensory nucleus)
- Anterolateral system carries exteroception :
1. Lat. Spinothalamic tract [pain & temp].
2. Ant. spinothalamic tract [crude touch].
3. Spino-reticular tract.
4. Spino-tectal tract.
Unconcious proprioceptive tracts to ————-, lie in ——————- formed of ———
cerebellum
superficially in the lat. Column
1. Two spino-cerebellar tracts (Post. & Ant.).
2. Spino-olivary tract.
Descending tracts (motor):
A. Pyramidal: lateral & anterior corticospinal tracts.
B. Extrapyramidal:
* 2 from the midbrain: rubro-spinal tract & tecto-spinal tract
* 2 reticulo-spinal tracts: medial & lateral.
* 2 Vestibulo-spinal tracts: medial & lateral.
* Olivo-spinal tract.
what is the Intersegmental tracts (propriospinal) u should mention its location parts describe axons connects btw
- Surround the grey matter forming the fasciculus proprius anterior, lateralis & posterior.
- Contains ascending and descending short axons of interneurons between adjacent segments of spinal cords.
Ascending Tracts is a —————- pathway formed of ————-
sensory 3 neurons (first , second, third order)
Ascending Tracts first order neuron is
always a pseudounipolar cell of the Dorsal Root Ganglion. It carries sensation by its peripheral process from receptors & conveys this sensation by its central processes to the dorsal root to the spinal cord.
Ascending Tracts Third-order Neuron
is always cells of the Ventral Postero-Lateral Nucleus of Thalamus (VPLN). Their axons pass through posterior limb of internal capsule, then through corona radiata to reach sensory area of cerebral cortex.
Pathway for pain & temperature from body
(1 order) free nerve ending in skin —> DRG (form dorsolateral (Lissauer’s) tract) –> Lamina II & III (Substantia gelatinosa of Rolandi) {2 order}—> cross to the opposite side in the ventral white commissure –> lateral spinothalamic tract—> spinal lemniscus –> VPLN in thalamus {3 order} —> Axons of VPLN of thalamus pass in posterior limb of internal capsule, then through corona radiata to reach sensory area of cerebral cortex.
pathway of Pain &temperature from the face
carried by the trigeminal nerve.
- First Neuron: is Trigeminal Ganglion (formed of pseudounipolar cells as DRG).
- Second Neuron: is Spinal Nucleus of Trigeminal. Its axons cross to opposite side forming trigemino-thalamic tract (lemniscus) —> (VPMN) of thalamus.
- Third Neuron:is VPMN of thalamus whose axons pass in internal capsule, then the corona radiata to reach sensory area of face in cerebral cortex.
the spinal lemniscus is formed of
lateral and ventral spinothalamic tract
lateral spinothalamic pathway vs. ventral spinothalamic pathway
(1 order )
in lateral spinothalamic before the DRG synapse with lamina 2+3 it will divide into ascending & descending branches for few segments Lissauer’s tract
in ventral spinothalamic pathway it will immediately synapse with lamina 4-7
the longest first order neuron pathway is
Pathway of conscious proprioception & fine touch (Gracile & Cuneate tracts) (Posterior column -Dorsal column tract)
