dorsal root

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Either of the two roots of a spinal nerve, consisting of sensory fibers and arising from the posterior section of the spinal cord.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun one of the two roots of a spinal nerve that passes dorsally to the spinal cord and that consists of sensory fibers