P. Bermejo, M.López, I.Larraya, J.L. Cobo, S.Ordóñez, J.A. Vega
The innocuous transcutaneous stimulation of nerves supplying the outer ear, has demonstrated to be as effective as the invasive direct stimulation of the vagus nerve for the treatment of some neurological and non-neurological disturbances.
Thus, the precise knowledge of external ear innervation is of maximal interest for the design of transcutaneous auricular nerve stimulation devices. We analyzed eleven outer ears, and the innervation was assessed by Masson’s trichromic staining, immunohistochemistry or immunofluorescence (neurofilaments, S100 protein and myelin-basic protein). In both the cavum conchae and auditory canal nerve profiles were identified between the cartilage and the skin, and out of the cartilage. The density of nerves, and of myelinated nerve fibers, was higher out of cartilage, and in the auditory canal with respect to de cavum conchae.
Moreover, the nerves were more numerous in the superior and posterior-inferior than in the anterior-inferior segments of the auditory canal. Present study established a precise nerve map of the human cavum conchae and the cartilaginous segment of the auditory canal demonstrating regional differences in the pattern of innervation of human outer ear.
These results may provide the neuroanatomical basis for the accurate design of auricular transcutaneous nerve stimulation devices.
©Walden Medical. Pictures of the outer ear innervation assessed by immunofluorescence .