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AREOLAR TISSUE, TENDONS, AND MUSCLES. 191 ;

bone ; from the tendon its fibres diverge from before backward, and are
inserted mainly into the nnder surface and body of the tongue, consti-
tuting the bulk of the structure of that organ. Some of its fibres pass
backward to the hyoid bone and to the side of the pharynx.
Relations.—On its median surface with its fellow of the opposite side,
from which it is separated within the tongue by the median raphe. Its
lateral surfaces are in contact with the lingualis, hyo-glossus, and stylo-
glossus muscles, the sublingual, the ranine vessel, the gustatory nerve,
and sublingual glands. The terminal portion of the hypoglossal nerve
penetrates its posterior part. The frsenum linguae is formed by the
union of the anterior ui)per borders of the two genio-glossus muscles,
which are covered by mucous membrane.
Variations.—This muscle is sometimes united with the genio-hyoid
muscle, or it may give a few fine bundles to the epiglottis, to the stylo-
hyoid, or to the smaller cornu of the hyoid bone.
Nerve.—This muscle is supplied by the hypoglossal nerve.
Action.—To draw forward and protrude the tongue.
The Lingualis muscle is a longitudinal fasciculus placed in the sub-
stance of the tongue, arising at the base and extending between the hyo-
glossus and genio-glossus muscles to the apex of the organ. Some of
•its fibres intermingle with the stylo-glossus and hyo-glossus. The
ranine artery (the terminal portion of the lingual artery) passes along
its under surface.
The Hyo-glossus is a thin quadrate muscle, arising from the upper
border and the lateral portion of the great cornu of the hyoid Ijone,
also from the lesser cornu. Its fibres pass upward and slightly forward
to the posterior half and lateral portions of the tongue ; they then
spread inward and forward over the dorsum, joining those of the stylo-
glossus toward the apex.
Relations.—The hyo-glossus is related by its external surface with the
digastric, stylo-hyoid, stylo-glossus, and mylo-hyoid muscles, also the
deep part of the submaxillary muco-salivary gland, and is crossed from
below upward by the duct of Wharton and by the hypoglossal and
lingual nerves. Its internal surface rests upon the posterior portion of
the genio-glossus and the origin of the middle constrictor of tlie pharynx
it is crossed by the lingual artery and the glosso-pharyngeal nerve.
Variations.—The lingual artery occasionally passes through the mus-
it is at times composed of a number of sepa-
cle near the hyoid bone ;
rate bundles. The muscles sometimes receive a slip, triticeo-glossus
(Bochdalek), from the thyro-hyoid ligament, which passes upward and
forward, lying on the inner side of the lingual artery and joining the
hyo-glossus.
Nerves.—The muscle receives branches of the hypoglossal nerve.
Action.—To aid in depressing the tongue.
The Stylo-glossus is the shortest and smallest of the styloid muscles,
and passes from the styloid process to the tongue. It arises from the
outer and anterior portion of the apex of the process, and passes for-
ward and slightly downward and inward to the posterior part of the
tongue, where it divides into two portions, the longitudinal and the oblique.
The Longitudinal Portion passes forward, and is inserted along the