Spinal Cord Anatomy

Posted bythespinebookPosted inAnatomy, Topics

Long Tracts (DC ST CT) 

  • DC Dorsal Tract (Posterior) 
    • Proprioceptive 
    • Cross at brainstem 
      • Ipsilateral deficit 
    • Central LE 
      • Sensory enters distally first (distal to proximal) so sacral is central 
  • CT Corticospinal Tract (Lateral) Pyramidal 
    • Motor 
    • Crosses at brainstem 
      • Ipsilateral deficit 
    • Central – UE 
      • Sensory enters distally first so sacral WAS central but then it crossed 
  • ST Spinothalamic Tract (Anterior) 
    • Pain (prick test) and temperature 
    • Decussate at level of entry 
      • Contralateral deficits 
    • Light touch unreliable 
      • Ascends in dorsal (ipsilateral) and spinothalamic (contralateral) 
    • Central – UE 
  • Spinocerebellar Tract 
    • Unconscious proprioception 

Cross Sectional 

  • White Matter 
    • Peripheral 
    • Ascending and descending tracts (long tracts) 
  • Grey Matter 
    • Central 
    • Cell body and synapses 
    • Ventral Horn – motor (LMN) – UMN is in the brain 
    • Dorsal Horn – sensory – second order neurons (1st order are in the dorsal root ganglions 
    • Pre-ganglionic nerves of Autonomic NS (neurogenic shock for injuries above mid thoracic) 

Circulation 

  • Anterior Spinal artery 
    • Primary of anterior 2/3 
    • Supplies 
      • Lateral corticospinal tract, ventral corticospinal tract 
      • Spinothalamic tract 
  • Posterior Spinal artery 
    • Dorsal sensory columns 
  • Artery of Adamkiewicz 
    • Largest anterior segmental artery 
    • Br of left posterior intercostal (br of aorta) 
    • Lower 2/3 of spinal cord 
    • Anatomic variation 
      • 75% left side between T8 and L1 

CSF 

  • Mechanical and immunological protection 
  • Choroid plexus permeable capillary ultrafiltrate  
  • Total CSF volume 150mL 
  • Formation 500cc/day (turnover 3 times per day) 

Incomplete Spinal Cord Syndromes 

  • Brown Sequard 
  • Anterior Cord 
  • Posterior Cord 
  • Central Cord 

Rubrospinal Tract 

  • Descending from cerebellum and cerebral cortex 
  • Motor 
  • Cross at pyramids 
  • Input from the red nucleus 
  • Influences alpha and gamma motor neurons (the third order LMNs of the corticospinal tract) 
    • Modulates motor tone 
      • Ie: Extensors relax while flexors contract 
    • Reflex activity 
    • Inhibits antigravity (cerebrate)