TRACTS Flashcards
DCML
ORIGIN
Think Columns, ARC, VPL, brod3,1,2
Receptors: muscle spindles, GTO’s, mechanoreceptors (ruffini endings, Pacinian, Meissner’s, merkle)
Primary afferent: PNS, enters CNS though DRG
1st order: prethalamic fibers: enter dorsal horn and ascending entire spinal cord. Synapse on second order neurons in medulla, known as dorsal column fiber here.
2nd order: Decussation fibers.
- UE synapse in nucleus cuneatus
- LE synapse in nucleus gracilis
decussation fibers=internal arcuate (think that the two column create an arc)
ascending fibers=medial lemniscus
Synapse on 3rd order fibers in thalamus
3rd. Order: thalamic relay fibers. Synapse in VPL in thalamus
Known as thalamocortical fibers
Ascending fibers travel through internal capsule to terminate in cerebral cortex
DESTINATION
Contralateral Cerebral cortex, postcentral gyrus, brodman’s 3.1.2
LOCATION
Run longitudinally in dorsal column
UE: fasciculus cuneatus (lateral)
LE: fasciculus gracilis (medial)
MAJOR FUNCTION
Touch discrimination, proprioception, vibration
Spinothalamic (STT)
Spinothalamic (STT), think jelly fish are painful and very white(ventral white decussation, VPL, brod 3,1,2
Ascending
Lightly myelinated
ORIGIN
Receptors: thermoreceptors, nociceptors, free nerve endings
Primary afferent: PNS
1st order: Prethalamic relay from DRG enter spinal cord though dorsal horn. Will synapse on 2nd order fiber in the dorsal horn
2nd order: synapse on 1st order fibers in the substantia gelatinosa
Decussation takes place here in ventral white commissure, they then ascending(via anterior lateral funiculus) rest of spinal cord/brainstem to 3rd order neurons in thalamus
3rd. Order: thalamic relay portion
will synapse on 2nd order fibers here in the VPL. Send projections through internal capsule to terminate on cerebral cortex
DESTINATION
Contralateral Cerebral cortex, postcentral gyrus, brodman’s 3.1.2
LOCATION
Anterolateral fasciculus
Can send off collateral branches to create LISSAUR’S TRACT
Leads to higher generator potentials
TYPE
Crude touch, pain, temperature, pressure
Spinocerebellar
Spinocerebellar (think paleocerebellum)
Primary afferent: PNS
1st order: Nucleus Dorsalis
2nd order: ascend to cerebellum
ventral SCT will decussate twice to end up on ipsilateral side
DESTINATION
Ipsilateral Cerebellum
TRAVEL IN:
Travel in lateral funiculus
Function
Touch, pressure, proprioception for movement correction
Spinospinal
Spinospinal
FUNCTION
Allow us to elicit response from spinal cord alone
Role in patterns and reflexes
ORIGIN/path
Axons originate in interneuronal gray, bifurcate ascending and descending linking spinal segments
DESTINATION
Other spinal cord segments
LOCATION
May cross midline allowing integration of R and L sides of spinal cord
Corticobulbar
ORIGIN
DESTINATION
LOCATION
MAJOR FUNCTION
TRACT: Corticobulbar
ORIGIN Cerebral cortex (prefrontal gyrus, postcentral gyrus) (BA #4, #312)
DESTINATION Axons leave as cranial nerves 3, 7, 8, 9, 10
LOCATION Descend down through internal capsule, form pyramids of medulla
MAJOR FUNCTION Innervates eyes, nose mouth, and face, controls LMN’s of CN
Corticospinal Tract
Lateral Corticospinal (CST - think an upside-down pyramid (at bottom - spinomedullary junction - you have decussation), UMN,LMN)
Voluntary muscle movements
UMN: coming from cerebral cortex travel down though internal capsule, forms pyramids of medulla
Decussation: spinomedullary junction
Synapse on LMN: occurs in the ventral horn, still in CNS. Can be inhibitory, or excitatory, largely INHIBITORY.
Efferent Fibers: exit through ventral root and enter PNS, final common pathway, ALWAYS excitatory
Lateral CST -> appendicular (think your arms are more lateral than your spinal cord)
Anterior CST -> Axial (think your nose is the most anterior)
LMN: polio (cell body), GBS & DM (axon), Myastenia gravis (Neuromuscular Junction)
