केंद्रीय नाड़ी संस्थान का वह भाग जो कशेरुका-नाल के भीतर स्थित रहता है।

A major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain. A long tubelike structure extending from the base of the brain through the vertebral canal to the upper lumbar region.