Anterolateral system Flashcards
Direct pathway
SC
Lateral thalamus
Somatosensory cortices
Indirect pathway
SC
RF
Medial thalamus
Cingulate, frontal, and Limbic cortices
Which fibers make up the ALS system
Spinothalamic, spino mesencephalic, spinoreticular, spinobulbar, spinohypothalamic
Spinothalamic pathway
Spine
Thalamus
VPL and VPI
Spinomesencephalic pathway
Spine
Midbrain RF and PAG
Spinobulbar pathway
Spine
various nuclie of the brain
SPinohypothalamic pathway
Spine
Hpothalamus and other nuclei
SPinoreticular pathway
Spine
Medulla, pons, midbrain (RF)
ALS SC blood supply. Injury?
sulcal branches anterior spinal a
Occlusion leads to patchy losses of nociceptive, thermal touch over CL side of body 2 segments below lesion. Anterolateral cordotomy results in complete loss.
ALS in medulla blood supply and injury?
Caudal 1/3rd: vertebral A
Rostral 2/3rds: PICA (occlusion results in loss of pain/temp over CL body and IL loss of pain/temp of face b/c of spinal trigeminal nucleus and tract)
ALS in pons blood supply
long circumferential branches of basilar
ALS in midbrain blood supply
short circumferential branches of posterior cerebral (also does PCML) and superior cerebellar A
Upper cervical lesion sx
Deficit of entire CL side of body
Upper thoracic lesion
Deficit in thorax and LE on CL side. UE is ok because they enter into the pathway more rostrally.
When do the tracts cross
In the anterior white commissure in the spinal cord
Spinal cord hemisection sx. Have the tracts crossed? What other systems are involved?
The ALS tracts have crossed! Involves ALS, PCML, and CTS.
CL ALS loss 2 levels below lesion (bc have crossed already)
IL PCML loss below lesion (these don’t cross until caudal medulla)
IL paralysis below lesion (CTS)
IL horner if at cervical levels
Caudal pons lesion sx. What other systems are invovled?/
ALS in medulla, ML in medulla, and spinal trigeminal tract and nucleus, ambiguus, area postrema
IL facial and lateral rectus paralysis (facial nucleus damage=IL loss)
IL facial loss of pain/therm
IL Horners
ALS loss of CL limbs and IL face (alternating hemianesthesia)
Dysphagia and dysarthria
NV (area postrema)
Mid to rostral pons lesion sx. What systems are invovled?
PCML, ALS, trigeminal nuclei
CL limb PCML and ALS loss
IL pain/therm and discrimative touch to face, paralysis of masticatory muscles
Midbrain lesion sx. Systems?
ALS, ML, and red nucleus
CL limb ALS loss
CL LE PCML loss; if more medial, include CL UE.
VPL lesion sx.
Transient CL hemiplegia
CL paresthesias to face, trunk, and UE/LE
CL facial/oral cavity (if VPM included) loss /diminution of pain/therm/proprio, as well as on CL limbs.
What is the target of primary afferents entering into the ALS sytem
Laminae I, II, and V of posterior horn
Once fibers are in the spinal cord, what do they move within
Move within the posterolateral fasciculus (Lissauer tract).
Which NTs are involved in rhe DRGs?
Glutamate, calcitonin-gene related peptide (CGRP), and substance P. Project most heavily onto laminae II.
Spinomesencephalic fibers contain what NT
VIP. For vasodilation.
