The given blank can be filled with afferent.
Afferent nerve fibers are the axonal projections, which arrives at a specific region, in opposition to the efferent projections that go away from the region. In the PNS, the efferent and the afferent projections are always from the point of view of the spinal cord.
The PNS afferents refer to the axons of sensory neurons conducting sensory information from all through the body, into the spine.