Henry Gray (18251861). Anatomy of the Human Body. 1918.
in lines parallel with the two rows of the papillæ vallatæ, excepting at the apex of the organ, where their direction is transverse. Projecting from their apices are numerous filamentous processes, or secondary papillæ these are of a whitish tint, owing to the thickness and density of the epithelium of which they are composed, which has here undergone a peculiar modification, the cells having become cornified and elongated into dense, imbricated, brush-like processes. They contain also a number of elastic fibers, which render them firmer and more elastic than the papillæ of mucous membrane generally. The larger and longer papillæ of this group are sometimes termed papillæ conicæ.
FIG. 1018 Semidiagrammatic view of a portion of the mucous membrane of the tongue. Two fungiform papillæ are shown. On some of the filiform papillæ the epithelial prolongations stand erect, in one they are spread out, and in three they are folded in. (See enlarged image)
The papillæ simplices are similar to those of the skin, and cover the whole of the mucous membrane of the tongue, as well as the larger papillæ. They consist of closely set microscopic elevations of the corium, each containing a capillary loop, covered by a layer of epithelium.
Muscles of the Tongue.The tongue is divided into lateral halves by a median fibrous septum which extends throughout its entire length and is fixed below to the