Abstract
The spatial orientation of the stapedial nerve fibers in the facial nerve trunk was investigated by serial sectioning method using adult guinea pig. The cross serial sections, Araldite embedded and toluidin blue stained, showed that the stapedial nerve emerging from the posteromedian aspect of the vertical segment, gradually ramified into small bundles toward the horizontal segment.
The stapedial nerve bundles intermingled into the facial trunk as they further ramified without investment into smaller bundles in the horizontal segment, while in the vertical segment they were encircled by the perineurium. The stapedial nerve fibers mainly distributed on the posterior side of the facial trunk.
By their small outer diameter (1-3μm) and their thin myeline sheath (0.2-0.3μm) they could be identified in the trunk.
