On the Innervation of Human Vestibulum Nasi with a few additional Observations on the Fine Structure of the Same

Abstract

The human vestibulum nasi is divided into the pays cutanea provided with vibrissae and the pars mucosa. The latter is again divisible into the cornified, the non-cornified and the transitional parts counting from the anterior end. The relative areas of the three parts are very variable locally and individually. The papillae are well developed in the cornified part, but posterior to it, they become much poorer.
The vegetative nerve fibres from remarkably well-developed plexus submucosus in the nasal gland layer, with their termination represented by the terminalreticulum. This stands in tactile control over the acini and the ducts of the nasal glands. The vegetative fibres running out from the plexus into the propria form also the well-developed terminalreticulum in the papillae. This may be to establish control over the blood capillaries strongly developed in the papillae.
The sensory nerves in the vestibulum nasi are generally not so good in development, the majority running as far as into propria, especially into the papillae, to end there or to ascend into the epithelium to become intraepithelial fibres.
The sensory terminations found in the papillae are divided into two broad types. The one comprises the unbranehed and the simple branched terminations. The former are composed of a single fibre ending sharply in the upper part of a papillae without branching out, while in the latter there are found a few rami sent out from the stem fibre which often develop to a simple arborized termination.
The second type comprises small corpuscular terminations. These consist of uncapsulated glomerular, genital nerve body-like and MEISSNER's tactile body-like terminations. The first of these three are rather abundant, but the other two are only rarely found.
The intraepithelial fibres are closely dependent on the development of papillae. In the transitional part they are very scarce and are represented by simple very fine fibres, because the papillae are very poor in development here. In the non-cornified mucous part they become somewhat thicker and often ramified. The intraepithelial fibres gain in size in the cornified mucous part, are oftener ramified and end close beneath the corneal plate. In the anterior area of this part, where the epithelium is covered with corneal scales, we find some peculiarly shaped intraepithelial fibres in the extremely thinned epithelium over strongly developed papillae, stout in thickness and low in stature. The epithelium, though it shows cornification, must be looked upon as belonging to a special mucous epithelium without showing an uninterrupted deciduation of epithelial scales, so that the intraepithelial fibres here may be regarded as normal growths.
Very rarely, degenerated intraepithelial fibres are found also in the pays cutanea of the nasal vestibule. These are assumed to be relics from embryonic life.
Intraepithelial fibres are also observed in the ducts of the nasal glands, but in very simple form and in very rare instance only.