Spine anatomy and pathology can be difficult, but it is an important part of neurology examinations including the boards and the RITE® exam. Here you will review vascular, traumatic, inflammatory, and other lesions of the cord and vertebrae using high-yield images, text, and practice questions.

Author: Steven Gangloff, MD

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Table of Contents

Table of Contents

Spinal Cord Anatomy

Vascular supply

  • The vertebral arteries and the aorta (via 10 medullary branches) provide the primary vascularization of the spinal cord by forming a single anterior spinal artery (ASA) and two posterior spinal arteries (PSA).
    • The largest medullary branch, the great anterior artery of Adamkiewicz, arises between T9 and L2 and supplies the lumbar enlargement.
    • The ASA supplies the anterior two-thirds of the spinal cord, and the PSA the posterior one third.
  • The upper thoracic (T1-T4) segments are in the zone between ascending and descending blood supply are thus acts as a watershed vulnerable to ischemic insult by hypoperfusion/hypotension.

Nerve root anatomy

  • Cervical nerve roots exit above the corresponding vertebrae and the C8 root exists above the T1 vertebrae.
  • Thoracic, lumbar, and sacral nerve roots exit below their corresponding vertebral body, laterally and superiorly through the neural foramina.
    • Therefore, a herniation at the L4-L5 disc interspace will compress the L4 nerve root as it exits.
  • Autonomic dysfunction can be an additional complication of spinal lesions above T6, and this is one of the leading causes of mortality in this population.
    • It presents with respiratory distress, impaired thermoregulation, lower urinary tract and GI complications, and cardiovascular dysfunction such as autonomic dysreflexia.
      • Autonomic dysreflexia is sudden episodic increases in blood pressure along with baroreceptor-mediated bradycardia in response to noxious visceral or cutaneous stimulation below the injury level.

Motor and sensory pathways

Afferent (Sensory) Pathways

spine anatomy and pathology of disease spinal cord pain and sensory pathway
Left: Dorsal column system receiving fine touch and proprioception input and delivering to the cortex after decussation in the medulla. Right: Spinothalamic tract receiving pain and temperature sensation and delivering to the cortex after decussation within the spinal cord.

Efferent (Motor) Pathway

spine pathway anatomy pathology: corticospinal tract diagram
The corticospinal tract sends motor instruction from the pre-central gyrus to muscles of the contralateral side after decussation in the pyramids of the medulla.

Spinal Cord Anatomy and Lesions

  • A cursory understanding of spinal cord anatomy will allow you to interpret the presenting features of diseases that target certain structures.
  • The diagram below includes commonly tested partial spine lesions and their anatomic correlates.
  • The anterior horn (AH) and corticospinal tracts (orange) relay efferent motor output. The dorsal columns (DC) transmit afferent fine touch and proprioception input to the brain. The spinothalamic tract (yellow) relays afferent pain and temperature sensation.
Spine anatomy and pathology partial spinal trauma anterior cord subacute combined degeneration tabes dorsals brown sequard ALS posterior cord syndrome
A: Normal spinal cord. Anterior horn (AH) and lateral corticospinal tracts (orange) relay efferent motor output. Dorsal columns (DC) transmit afferent fine touch and proprioception input to the brain. Spinothalamic tract (yellow) relays afferent pain and temperature sensation. B: Anterior cord syndrome/infarct. Damage marked in red. C: Posterior cord syndrome or tabes dorsalis of tertiary syphilis. D: Subacute combined degeneration from B12 deficiency. E: Brown-Sequard cord hemisection. F: Central cord syndrome or syrinx. G: Poliomyelitis. H: Amyotrophic lateral sclerosis.


 

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Table of Contents

Table of Contents