Spinal Tracts Maja Solbakken Illustra(ons by Peder Olai Skjeflo Holman What are tracts? Tract = highway Connec4ng lower and higher CNS Nerve = lane Nerve signal = car Useful definions Nucleus Ganglion Neuron Nerve Tract A collecon of A collecon of The structural A bundle of An ascending nerve cell nerve cell and func4onal 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, communicaon sensory and connecng lower motor and higher CNS. informaon from one body part to another. The Spinal Cord High Yields: • What sensaons the tract TRANSMITS • Where the neurons SYNAPSE • Where there are DECUSSATIONS Sensaons • Temperature Not transmiKed by the • Pressure tracts: • Pain • Visualizaon • Fine touch • Audi4on • Crude touch • Olfac4on • Propriocep4on • Gustaon • Vibraon Synapse Decussa7on = 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 Lemniscus pathway 2. Spinothalamic tract Dorsal Column-Medial Lemniscus Pathway (Spinobulbothalamocor7cal tract) Transmission of precise sensaon: • Fine touch • Pressure • Vibraon • Propriocep4on Did you get it? Importance of T4 § Upper body § Lower body DORSAL COLUMN MEDIUM LEMNISCUS Transmission Synapses 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 • Propriocep4on nucleus (thalamus) medial lemniscus Spinothalamic Tract Transmission of diffuse sensaon: • Pain • Temperature • Crude touch Did you get it? 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 brainstem) Cor7cospinal Tract (Pyramidal tract) Transmission of: • Motor func4on to contralateral limb Did you get it? CORTICOSPINAL TRACT Transmission Synapses Decussaon • Motor func4on to 1. order neuron: Giant cells of Betz in • 75 – 90% in pyramidal contralateral limb precentral gyrus (motor corteX) decussaDon (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 • Propriocep4on 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 CorDcospinal tract • Motor func4on 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 MaSer Nerve Ganglion Commissural Associaon CorteX Nuclei Tracts Fibers Fibers .