5 SPINAL TRACTS
2 motor - cortico –> spinal (pyramidal) vs extrapyramidal
P = Lateral / Anterior
Lateral = 90% of mvnt = Motor cortex > Thalamus internal capsule > medulla ( CROSSOVERS) > Down spine > motor neuron
Anterior = 8% = Motor cortex > thalamus > medulla > down spine (CROSSOVER at AWC) > motor neuron
EP = VORR
Vestibulo - eye
Olivo - cerebellum
ReTiculo - Tone
Rubro - voluntary
3 sensory - DCML touch + Spinothalamic pain + Spinocerebellar Msk spindle FB
[DCML = A-beta (Touch Pressure Lateral Inhibition)
1st ) Touch - Up cord
2nd) CuneAte Arm / GraciLe Leg nucleus in medulla > MEDULLA CROSSOVER “Lemniscus decussation” to pons > Pons to Thalamus is “Medial lemniscus “
3rd) Thalamus to Parietal homunculus
[2 Spinocerebellar = A gamma - Msk Spindle FB (golgi tendon apparatus)
[2 Spinothalamic = Fast vs Slow
A-delta - Fast Pain high localization
NFL - Neo + Fast pain + Lateral
1st order - Glutamate > Lamina 1
2nd order - AWC crossover up cord to 3rd order
3rd order - Thalamus to parietal
Slow Pain = C fibers - Slow Pain ( mild dull achy pain + Temp + tickle ) poor localization
OOO - PaleO + SlOw Pain + AnteriOr
1st order - Glutamate,CGRP,Substance P > Lamina 2,3 (substantia gelatinosa) + 5
2nd order - Crossover AWC up cord
3rd order - Thalamus to parietal
Pain
Pain via anterior or lateral spinothalamic > responds w DIC > 1st Peri aqua gray release Enkephalin > 2nd on Ralph release 5ht serotonin > 3rd enk neuron release Enkephalin > bind to mu allows k+ efflux (hyperpolarize lamina 1235) and spreads via tract of Lissauer= less sensitive to pain
Acidosis (Low pH <7.35 / High H+ ions) > Hyperkalemia ECF K+ > INC Sensitivity to PAIN && H+ Directly causes Pain.
H+ goes in pushes K+ out > making cell more positive inside (INC nociceptor excitability)
At rest, ICF K+ already wants to leave dt high [C] “chemical force” but stays dt “electrical force” opposite attraction of positive ion to negative cell.
+DF = Ion will move out of cell if cation, and into cell if anion / -DF = IN if cation, OUT if anion. Greater the difference the stronger the force influencing movement.
Other - inflammation > bradykinin histamine (direct) prostaglandin (indirect)
Serotonin, ACH stimulatory for free nerve endings
Temp < 5 and > 45
Pain is proportional to how fast tissue is actively damaged
Parietal = Pericarditis (heart) , Peritoneum (abd), Pleurisy (lungs) = sharp fast pain A delta fiber
Visceral = dull organ pain - C fiber
Referred pain = Remote Pain felt dt close proximity of tissue in utero
- chest pain - out to L upper chest shoulder anterior upper/lower arm
-esophagus similar to heart to upper arm
- Appendix has both visceral dull organ pain in RLQ, once worse, parietal sharp pain felt near umbilicus at T10.
CSF Circulation
Choroid plexus = horns + 3rd + 4th… Csf 150 circulates x 3 = ~500 ml/day
Lateral horns - inferior > posterior > central > Anterior > Foramen of Monroe “inter ventricular” > 3rd ventricle > cerebral aqueduct “sylvius” > 4th ventricle > 4 ways = central canal + median magendie + 2 Lateral luschka.
Circulates until INC icp > drain into arachnoid granulations — Superior / inferior (straight) sagittal sinus > sinus confluence > transverse sinus > sigmoid sinus > IJ
Tentorium cerebelli - connective tissue shelf between cerebellum and upper cortex brain
Falx Cerebri - connective tissue between L and R hemisphere and superior and inferior sagittal sinus
Circle of Willis
11 = Ant comm > Anterior 1 pre > Middle / Internal carotid > Post Comm > Posterior 2 post
