Spinal Tracts Maja Solbakken Illustraons by Peder Olai Skjeflo Holman

What are tracts?

Tract = highway Connecng lower and higher CNS Nerve = lane Nerve signal = car Useful definions Nucleus Ganglion

A collecon of A collecon of The structural A bundle of An ascending nerve cell nerve cell and funconal fibers (sensory) or bodies inside bodies outside units of the (fascicles) using descending the CNS the CNS. electrical and (motor) pathway specialized for chemical signals for sensory or motor nerve rapid to transmit impulses, communicaon sensory and connecng lower motor and higher CNS. informaon from one body part to another.

The

High Yields:

• What sensaons the tract TRANSMITS • Where the • Where there are Sensaons • Temperature Not transmied by the • Pressure tracts: • • Visualizaon • Fine touch • Audion • Crude touch • Olfacon • Propriocepon • Gustaon • Vibraon Synapse Decussaon = to cross over Logically Interpreng 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 pathway 2. Dorsal Column- Pathway (Spinobulbothalamocorcal tract)

Transmission of precise sensaon: • Fine touch • Pressure • Vibraon • Propriocepon

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Importance of T4 § Upper body § Lower body

DORSAL COLUMN MEDIUM LEMNISCUS

Transmission Decussaon

• Fine touch 1. order neuron: DRG Decussate as internal • Pressure 2. order neuron: Cuneate & Gracile nuclei arcuate fibers in the • Vibraon 3. order neuron: ventral posterolateral medulla, then become • Propriocepon nucleus () medial lemniscus Spinothalamic Tract

Transmission of diffuse sensaon: • Pain • Temperature • Crude touch

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SPINOTHALAMIC TRACT

Transmission Synapses Decussaon

• 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. Corcospinal (pyramidal) 2. Corcobulbar (pyramidal, ending in the ) Corcospinal Tract (Pyramidal tract)

Transmission of: • Motor funcon to contralateral limb

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CORTICOSPINAL TRACT

Transmission Synapses Decussaon

• Motor funcon to 1. order neuron: Giant cells of Betz in • 75 – 90% in pyramidal contralateral limb precentral gyrus () decussaon (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 Decussaon 1. order Dorsal column- • Fine touch DRG Medulla (as internal neuron medial lemniscus • Pressure arcuate fibers) 2. order Gracile or Cuneate pathway • Vibraon neuron nucleus • Propriocepon 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 Corcospinal tract • Motor funcon 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 maer White Maer Nerve Ganglion

Commissural Associaon Cortex Nuclei Tracts Fibers Fibers