SECT. 130.] THE TONGUE. 1&<) 



homogeneous, and contain no distinct cavity or nucleolus; or, 

 instead of the latter, merely some granules. In its chemical con- 

 stitution, the pavement epithelium of the oral cavity agrees, as far 

 as is known, in all essential points with the mucous layer and the 

 lowermost strata of the horny layer of the epidermis, and particu- 

 larly in this respect, that even the plates readily swell up in alkalies, 

 on which account we refer the reader to § 47. 



The epithelium of the oral cavity is, so to speak, subject to a constant 

 desquamation, which, however, appears to depend as little here as in the 

 epidermis on special vital conditions of the mucous membrane of the epi- 

 thelial cells, but is rather the consequence of the various mechanical influ- 

 ences to which the oral membrane is subject in mastication and in speaking. 

 The regeneration of the cells goes on in the deeper portions as in the 

 epidermis. 



The epithelium of the oral cavity, although thick, is readily permeated by 

 fluids, and is, in this respect, essentially distinguished from the epidermis, 

 which presents similar relations only in its mucous layer. 



Of the Tongue. 



§ 130. The Tongue is a muscular mass attached to a special 

 oone — the hyoid bone — and covered by the mucous membrane of 

 the oral cavity. Its constituent fibres, o-ooo/" to 0-023"' in breadth, 

 are distinguished from those of the extrinsic transversely striped 

 muscles by their being variously interwoven, so that the well- 

 known lingual muscles cannot be demonstrated as separate organs 

 in the interior of the tongue, but only as secondary bundles and 

 as muscular fibres. 



The two genio-glossi, the musculus transversus linguae, and the 

 fibro -cartilage of the tongue, form, to a certain extent, the frame- 

 work of the organ. The fibro-cartilage, also called lingual cartilage, 

 is a dense, whitish-yellow, fibrous plate, placed vertically in the 

 middle of the tongue between the two genio-glossi ; it extends the 

 whole length of the organ, but scarcely deserves the name be- 

 stowed upon it, since it is composed of ordinary tendinous or 

 ligamentous tissue. It begins at the hyoid bone, in connection 

 with a broad fibrous lamella, membrana hyo-glossa (Blandin), 

 which passes from the hyoid bone to the root of the tongue, and 

 covers the end of the genio-glossus ; it then very soon reaches the 

 same height as the musculus transversus, and gradually decreases 

 at the anterior third of the tongue towards the apex, where it 

 disappears. The septum Ungues, as this fibrous mass, o - i2'" thick, 

 is best called, reaches upwards as far as i\'" or 2'" distance from 



