Spinal Cord

About the Spinal Cord

The spinal cord is approximately 45 cm long, extending from the foramen magnum to the conus medullaris at L1 to L2 in adults. It gives rise to 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal. Below L2, the cauda equina nerve roots fill the spinal canal. The cord has central gray matter H shaped with dorsal sensory horns and ventral motor horns, and surrounding white matter with ascending sensory tracts dorsal columns, spinothalamic, spinocerebellar and descending motor tracts corticospinal. The dorsal column medial lemniscus pathway carries fine touch, vibration, and proprioception. The spinothalamic tract carries pain and temperature. The lateral corticospinal tract carries voluntary motor signals, crossing at the medulla. Spinal cord injury causes deficits below the lesion level. Brown Sequard syndrome hemisection causes ipsilateral motor and proprioception loss with contralateral pain and temperature loss. Reflexes including the knee jerk patellar L2 to L4 do not require the brain.