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Spinal Cord: Function, Structure & Importance

The Spinal Cord: Structure, Function & Clinical Significance

The spinal cord is the primary information highway between the brain and body—a cylindrical neural structure extending from the foramen magnum to L1-L2 vertebral level in adults.

Gross Anatomy

  • Length: ~45 cm (men), ~43 cm (women)
  • Segments: 31 pairs of spinal nerves (8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal)
  • Enlargements: Cervical (C5-T1, upper limb), lumbosacral (L2-S3, lower limb)
  • Termination: Conus medullaris → filum terminale → coccyx
  • Protection: Vertebral column, meninges (dura, arachnoid, pia), CSF

Internal Organization

  • Gray matter (butterfly-shaped): Neuron cell bodies. Dorsal horn (sensory), ventral horn (motor), intermediate zone (autonomic/interneurons).
  • White matter: Myelinated tracts. Dorsal columns (ascending sensory), lateral/ventral columns (ascending + descending motor/autonomic).
  • Central canal: CSF-filled, continuous with ventricular system.

Core Functions

  1. Conduction: Ascending sensory pathways (touch, pain, temp, proprioception) to brain; descending motor commands (corticospinal, rubrospinal, vestibulospinal, reticulospinal) to effectors.
  2. Reflex integration: Monosynaptic (stretch reflex), polysynaptic (withdrawal, crossed extensor), autonomic reflexes (bladder, bowel, cardiovascular).
  3. Central pattern generators: Locomotor rhythm generation (spinal cord can produce stepping patterns without brain input).
  4. Autonomic regulation: Sympathetic (T1-L2), parasympathetic (S2-4) outflow for visceral control.

Clinical Syndromes

SyndromeKey Features
Complete transectionParalysis, sensory loss, areflexia below level; neurogenic shock (cervical/high thoracic)
Anterior cord syndromeMotor loss + pain/temp loss below level; proprioception spared
Central cord syndromeUpper > lower extremity weakness; cape-distribution sensory loss; often cervical hyperextension injury
Brown-SéquardIpsilateral motor/proprioception loss + contralateral pain/temp loss below lesion

Recovery & Rehabilitation

Neuroplasticity, spared pathway recruitment, and intensive rehab (PT, OT, locomotor training, FES, robotics) drive recovery. Prognosis depends on injury level, completeness (ASIA grade), age, and timing of intervention.

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