part of posterior spinal root BTO:0000360 BrendaTissueOBO The sensory division of each spinal nerve, attached centrally to the spinal cord and joining peripherally with the anterior (motor) root to form the nerve before it emerges through the intervertebral foramen: each posterior root bears a spinal ganglion and conveys sensory fibers to the spinal cord. There are 31 anterior and 31 posterior nerve roots: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. dorsal root of spinal nerve posterior root of spinal nerve radix posterior nervi spinalis root dorsali nervi spinalis root sensoria nervi spinalis sensory root of spinal nerve sensory spinal root spinal root