Projections of two hindlimb cutaneous nerves to cat dorsal horn.

Abstract

The dorsal horn (laminae III and IV) projections of 2 cutaneous nerves, a branch of the posterior femoral cutaneous nerve (PFCN3) and the lateral sural nerve (LSN), were traced using horseradish peroxidase (HRP) and the tetramethylbenzidine (TMB) reaction. The PFCN3 projection was always lateral to the LSN projection; both skirt the enlarged toe representation in L[lumbar]7 their mediolateral extents widen in S[sacral]1 with the PFCN3 projection widening caudal to the LSN projection. Substantial interanimal variation was encountered. Both nerves project only to the ipsilateral dorsal horn, and the left and right dorsal horn projections of a given nerve are mirror-symmetric. It was possible to examine the relationship between LSN and PFCN3 projection fields in the same cat by examining the 2 fields on opposite sides. The LSN and PFCN3 cutaneous innervation fields are adjacent and nonoverlapping, and their dorsal horn projection fields are adjacent and nonoverlapping. The projections of these 2 nerves are in accord with the suggestion of Brown and Fuchs that the presynaptic terminal neuropil in the dorsal horn is somatotopically organized.