Spinal Tracts Maja Solbakken Illustra ons by Peder Olai Skjeflo Holman
What are tracts?
Tract = highway Connec ng lower and higher CNS Nerve = lane Nerve signal = car Useful defini ons Nucleus Ganglion Neuron Nerve Tract
A collec on of A collec on of The structural A bundle of An ascending nerve cell nerve cell and func onal fibers (sensory) or bodies inside bodies outside units of the (fascicles) using descending the CNS the CNS. nervous system electrical and (motor) pathway specialized for chemical signals for sensory or motor nerve rapid to transmit impulses, communica on sensory and connec ng lower motor and higher CNS. informa on from one body part to another.
The Spinal Cord
High Yields:
• What sensa ons the tract TRANSMITS • Where the neurons SYNAPSE • Where there are DECUSSATIONS Sensa ons • Temperature Not transmi ed by the • Pressure tracts: • Pain • Visualiza on • Fine touch • Audi on • Crude touch • Olfac on • Propriocep on • Gusta on • Vibra on Synapse Decussa on = to cross over Logically Interpre ng the tracts
Origin →Destination • Δορσαλ χολυµν-µεδιαλ λεµνισχυσ • Σπινοτηαλαµιχ • Χορτιχοσπιναλ • Σπινοχερεβελλαρ • Χορτιχοβυλβαρ (παρτ οφ πψραµιδαλ τραχτ)
Αφφερεντ (ασχενδινγ) = σενσορψ τραχτ Εφφερεντ (Δεσχενδινγ) = µοτορ τραχτ Sensory tracts 1. Dorsal Column-Medial Lemniscus pathway 2. Spinothalamic tract Dorsal Column-Medial Lemniscus Pathway (Spinobulbothalamocor cal tract)
Transmission of precise sensa on: • Fine touch • Pressure • Vibra on • Propriocep on
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Importance of T4 § Upper body § Lower body
DORSAL COLUMN MEDIUM LEMNISCUS
Transmission Synapses Decussa on
• Fine touch 1. order neuron: DRG Decussate as internal • Pressure 2. order neuron: Cuneate & Gracile nuclei arcuate fibers in the • Vibra on 3. order neuron: ventral posterolateral medulla, then become • Propriocep on nucleus (thalamus) medial lemniscus Spinothalamic Tract
Transmission of diffuse sensa on: • Pain • Temperature • Crude touch
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SPINOTHALAMIC TRACT
Transmission Synapses Decussa on
• Pain 1. order neuron: DRG Anterior white • Temperature 2. order neuron: Nucleus Proprius of dorsal commissure of spinal • Crude touch horn (Spinal cord) cord 3. order neuron: Ventral posterolateral nucleus (thalamus)
Lateral white column of spinal cord = Lateral spinothalamic tract Anterior white column = Ventral spinothalamic tract Motor Tracts 1. Cor cospinal (pyramidal) 2. Cor cobulbar (pyramidal, ending in the brainstem) Cor cospinal Tract (Pyramidal tract)
Transmission of: • Motor func on to contralateral limb
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CORTICOSPINAL TRACT
Transmission Synapses Decussa on
• Motor func on to 1. order neuron: Giant cells of Betz in • 75 – 90% in pyramidal contralateral limb precentral gyrus (motor cortex) decussa on (to contralateral 2. order neuron: Anterior horn cells of lateral white column) spinal cord • 10 – 25% in anterior white commissure of spinal cord SUMMARY OF TRACTS OF THE SPINAL CORD NeuroanatomyTransmission Crash CourseSynapses Decussa on 1. order Dorsal column- • Fine touch DRG Medulla (as internal neuron medial lemniscus • Pressure arcuate fibers) 2. order Gracile or Cuneate pathway • Vibra on neuron nucleus • Propriocep on 3. order VPL (thalamus) neuron 1. order Spinothalamic tract • Pain DRG Anterior white neuron • Temperature commissure (AWC) 2. order Nucleus proprius • Crude touch neuron 3. order VPL (thalamus) neuron 1. order Cor cospinal tract • Motor func on Giant cells of Betz Medullary pyramids, neuron AWC 2. order Anterior horn cells neuron THANK YOU FOR BEING AWESOME Anatomical Structure of the N.S. Nervous System
CNS PNS
Grey ma er White Ma er Nerve Ganglion
Commissural Associa on Cortex Nuclei Tracts Fibers Fibers