The Longitudinalis linguæ superior

is a thin stratum of oblique and longitudinal fibers immediately underlying the mucous membrane on the dorsum of the tongue. It arises from the submucous fibrous layer close to the epiglottis and from the median fibrous septum, and runs forward to the edges of the tongue.	95
FIG. 1020– Coronal section of tongue, showing intrinsic muscles. (Altered from Krause.) (See enlarged image)
The Longitudinalis linguæ inferior (Inferior lingualis) is a narrow band situated on the under surface of the tongue between the Genioglossus and Hyoglossus. It extends from the root to the apex of the tongue: behind, some of its fibers are connected with the body of the hyoid bone; in front it blends with the fibers of the Styloglossus.	96
The Transversus linguæ (Transverse lingualis) consists of fibers which arise from the median fibrous septum and pass lateralward to be inserted into the submucous fibrous tissue at the sides of the tongue.	97
The Verticalis linguæ (Vertical lingualis) is found only at the borders of the forepart of the tongue. Its fibers extend from the upper to the under surface of the organ.	98
The median fibrous septum of the tongue is very complete, so that the anastomosis between the two lingual arteries is not very free.	99
Nerves.—The muscles of the tongue described above are supplied by the hypoglossal nerve.	100
Actions.—The movements of the tongue, although numerous and complicated, may be understood by carefully considering the direction of the fibers of its muscles. The Genioglossi, by means of their posterior fibers, draw the root of the tongue forward, and protrude the apex from the mouth. The anterior fibers draw the tongue back into the mouth. The two muscles acting in their entirety draw the tongue downward, so as to make its superior surface concave from side to side, forming a channel along which fluids may pass toward the pharynx, as in sucking. The Hyoglossi depress the tongue, and draw down its sides. The Styloglossi draw the tongue upward and backward. The Glossopalatini draw the root of the tongue upward. The intrinsic muscles are mainly concerned in altering the shape of the tongue, whereby it becomes shortened, narrowed, or curved in different directions; thus, the Longitudinalis superior and inferior tend to shorten the tongue, but the former, in addition, turn the tip and sides upward so as to render the dorsum concave, while the latter pull the tip downward and render the dorsum convex. The Transversus narrows and elongates the tongue, and the Verticalis flattens and broadens it. The complex arrangement of the muscular fibers of the tongue, and the various directions in which they run, give to this organ the power of assuming the forms necessary for the enunciation of the different consonantal sounds; and Macalister states “there is reason to believe that the musculature of the tongue varies in different races owing to the hereditary practice and habitual use of certain motions required for enunciating the several vernacular languages.”	101