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  <head>
    <title>081-01 Spinal cord organisation, ascending pathways, descending tracts, and lesion patterns</title>
    <ownerName>Integrated Medical Foundations</ownerName>
  </head>
  <body>
    <outline text="Spinal cord organisation and lesion patterns">
      <outline text="Segments and orientation">
        <outline text="Deficit set by level, side, tract, crossing, somatotopy"/>
        <outline text="Medulla to conus near L1 or L2">
          <outline text="Column outgrows cord, roots descend as cauda equina"/>
        </outline>
        <outline text="Dorsal-root ganglion: pseudounipolar sensory bodies"/>
        <outline text="Ventral root: somatic and preganglionic motor axons"/>
        <outline text="Level by proportions">
          <outline text="Cervical: abundant white matter"/>
          <outline text="Lumbar: broad grey horns"/>
          <outline text="Thoracic: lateral horn"/>
        </outline>
      </outline>
      <outline text="Grey-matter circuits">
        <outline text="Dorsal horn receives afferents">
          <outline text="Superficial: nociception and temperature"/>
          <outline text="Deeper: touch and proprioception"/>
        </outline>
        <outline text="Ventral horn lower motor neurons">
          <outline text="Medial axial and proximal, lateral distal"/>
          <outline text="Alpha extrafusal, gamma spindle sensitivity"/>
        </outline>
        <outline text="Intermediate zone">
          <outline text="Sympathetic intermediolateral column T1 to L2"/>
          <outline text="Sacral parasympathetic S2 to S4"/>
          <outline text="Clarke nucleus relays proprioception to cerebellum"/>
        </outline>
        <outline text="Reflexes">
          <outline text="Stretch reflex monosynaptic core, modulated"/>
          <outline text="Intensity reflects central and peripheral excitability"/>
        </outline>
      </outline>
      <outline text="Dorsal column-medial lemniscus">
        <outline text="Touch, vibration, conscious proprioception"/>
        <outline text="First-order axons ascend ipsilaterally">
          <outline text="Gracilis lower body medial, cuneatus upper lateral"/>
        </outline>
        <outline text="Synapse in gracile and cuneate nuclei"/>
        <outline text="Internal arcuate fibres cross, medial lemniscus">
          <outline text="Ventral posterolateral thalamus to sensory cortex"/>
        </outline>
        <outline text="Cord lesion: ipsilateral loss below"/>
        <outline text="Sensory ataxia worse with eyes closed"/>
      </outline>
      <outline text="Anterolateral system">
        <outline text="Pain, temperature, itch, crude touch"/>
        <outline text="Lissauer tract, then dorsal horn synapse"/>
        <outline text="Cross in anterior white commissure">
          <outline text="Contralateral loss begins slightly below lesion"/>
        </outline>
        <outline text="Spinothalamic: localisation and discrimination"/>
        <outline text="Spinoreticular, spinomesencephalic: arousal, modulation"/>
        <outline text="Syrinx damages crossing fibres">
          <outline text="Bilateral segmental loss, dorsal columns spared"/>
        </outline>
      </outline>
      <outline text="Spinocerebellar pathways">
        <outline text="Posterior tract from Clarke nucleus, inferior peduncle"/>
        <outline text="Anterior tract crosses twice, ends ipsilateral"/>
        <outline text="Cerebellum compares intended and actual movement"/>
        <outline text="Lesion: ipsilateral ataxia, no conscious loss"/>
      </outline>
      <outline text="Motor pathways">
        <outline text="Corticospinal via internal capsule and pyramids">
          <outline text="Most cross at pyramidal decussation"/>
          <outline text="Cord lesion ipsilateral, above medulla contralateral"/>
        </outline>
        <outline text="Lateral tract: fractionated distal movement"/>
        <outline text="Anterior tract: axial muscles"/>
        <outline text="Brainstem motor tracts">
          <outline text="Reticulospinal: posture, tone, locomotion"/>
          <outline text="Vestibulospinal: stability, antigravity"/>
          <outline text="Tectospinal orients, rubrospinal upper limb"/>
        </outline>
        <outline text="Upper motor neuron: hyperreflexia, clonus, plantar"/>
        <outline text="Lower motor neuron: atrophy, fasciculation, hyporeflexia"/>
        <outline text="Cord level gives mixed pattern"/>
      </outline>
      <outline text="Autonomic pathways">
        <outline text="Hypothalamospinal fibres in dorsolateral cord">
          <outline text="Cervical lesion can cause Horner syndrome"/>
        </outline>
        <outline text="Bladder needs pontine and cortical coordination">
          <outline text="Suprasacral: detrusor-sphincter dyssynergia"/>
          <outline text="Conus, cauda, peripheral: areflexic"/>
        </outline>
        <outline text="High injury: neurogenic shock"/>
        <outline text="Above about T6: autonomic dysreflexia"/>
      </outline>
      <outline text="Arterial territories">
        <outline text="Anterior spinal artery: anterior two-thirds">
          <outline text="Infarct: bilateral motor and pain-temperature loss"/>
        </outline>
        <outline text="Posterior spinal arteries: dorsal columns and horns"/>
        <outline text="Lower cord depends on artery of Adamkiewicz"/>
        <outline text="Border zones vulnerable in aortic surgery"/>
      </outline>
      <outline text="Canonical spinal syndromes">
        <outline text="Brown-Séquard hemicord">
          <outline text="Ipsilateral weakness and dorsal-column loss"/>
          <outline text="Contralateral pain-temperature loss below"/>
        </outline>
        <outline text="Central cord: upper limbs worst"/>
        <outline text="Anterior cord: dorsal columns spared"/>
        <outline text="Posterior cord: sensory ataxia"/>
        <outline text="Conus: early symmetric saddle and sphincter loss"/>
        <outline text="Cauda: asymmetric radicular, lower motor signs"/>
      </outline>
      <outline text="Localisation strategy">
        <outline text="Start from highest abnormal level"/>
        <outline text="One pattern should explain every finding"/>
        <outline text="Sacral sparing suggests incomplete central lesion"/>
        <outline text="Interpret imaging against anatomy"/>
      </outline>
    </outline>
  </body>
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