UNMYELINATED FIBERS IN HUMAN GREATER AURICULAR AND SURAL NERVES - A COMPARATIVE MORPHOMETRIC STUDY

Since normal structural details of human greater auricular nerve (GAN) have not as yet been studied with modern techniques, light and electr on microscopic findings of seven presumably normal GANs, obtained from five patients during radical neck dissection, were compared with thos e of normal sural nerves (SNs). In GANs there was a tendency to higher densities per mm(2) and a larger number of small-diameter fibers in m yelinated fibers (MFs) and unmyelinated fibers (UFs) without obvious s igns of de- or regeneration. UF histograms were unimodal in both group s, with mean UF diameters being somewhat smaller in GANs than in SNs. Schwann cell complexes containing several or even numerous UFs were mo re frequent in GANs than in SNs. In GANs, UF often occurred focally in great numbers within large Schwann cell complexes (polyaxonal complex es), not commonly seen in normal SNs. It is concluded that these struc tural peculiarities in GANs reflect natural conditions in short sensor y nerves irrespective of any specific function.