INNERVATION OF THE RAT EXTERNAL AUDITORY MEATUS - A RETROGRADE TRACING STUDY

The innervation of the rat external auditory meatus has contributions from several nerves. Fluorogold, a retrograde neuronal tracer, was use d to determine the relative contributions from neurons in cranial and spinal ganglia, and to distinguish any difference in the sensory and m otor innervation between the outer cartilaginous and inner bony portio ns. The following ganglia were examined: the trigeminal, geniculate, g lossopharyngeal, vagal, superior cervical, and dorsal root (C2-C4) gan glia. All selected ganglia demonstrated innervation of the external ea r canal, particularly the trigeminal, glossopharyngeal, facial, and va gal ganglia. The geniculate and glossopharyngeal ganglia contributed m ore innervation to the inner osseous portion than to the outer cartila ginous portion of the external ear canal, and the vagal ganglion contr ibuted relatively equally.