Final answer:
Root hair plexuses are networks of fibers or vessels that arise from spinal nerves and contain sensory or motor fibers. They are located within the spinal cord.
Step-by-step explanation:
Root hair plexuses are network of fibers or vessels that arise from spinal nerves and contain sensory or motor fibers. In the case of root hair plexuses, they contain sensory fibers from cutaneous or peripheral sensory surfaces and motor fibers from motor neurons of the spinal cord. These sensory fibers send action potentials to the central nervous system, while motor fibers cause skeletal muscles to contract in their target regions.
Root hair plexuses are located within the spinal cord, specifically in the dorsal and ventral nerve roots.