THE MUSCLES AND FASCIAE. 



corresponding with its point of attachment to the lower jaw, its base with its 

 insertion into the tongue and hyoid bone. It arises by a short tendon from the 

 superior genial tubercle on the inner side of the symphysis of the jaw, immediately 

 above the Genio-hyoid ; from this point the muscle spreads out in a fan-like form, 

 a few of the inferior fibres passing downward, to be attached by a thin aponeurosis 

 into the upper part of the body of the hyoid bone, a few fibres passing between 

 the Hyo-glossus and Chondro-glossus to blend with the Constrictor muscles of the 

 pharynx ; the middle fibres passing backward, and the superior ones upAvard and 

 forward, to enter the whole length of the under surface of the tongue, from the 

 base to the apex. The two muscles lie on either side of the median plane; behind, 

 they are quite distinct from each other, and are separated at their insertion into 

 the under surface of the tongue by a tendinous raplKj, which extends through the 

 middle of the organ ; in front, the two muscles are more or less blended : distinct 

 fasciculi are to be seen passing off from one muscle, crossing the middle line, 

 and intersecting with bundles of fibres derived from the muscle on the other side 

 (Fig. 205). 



Relations. By its internal surface it is in contact with its felloAv of the opposite 

 side; by its external surf ace, with the Inferior lingualis, the Hyo-glossus, the lin- 

 gual artery and hypoglossal nerve, the lingual nerve, and sublingual gland ; by 



its upper border, with the mucous membrane of 

 the floor of the mouth (fraenum lingure); by its 

 lower border, with the Genio-hyoid. 



The Hyo-glossus is a thin, flat, quadrilateral 

 muscle which arises from the side of the body 

 and whole length of the greater cornu of the 

 hyoid bone, and passes almost vertically upward 

 to enter the side of the tongue, between the 

 Stylo-glossus and Lingualis. Those fibres of 

 this muscle which arise from the body are 

 directed upward and backward, overlapping 

 those arising from the greater corriu, which are 

 directed upward and forward. 



Relations. By its external surface, with the 

 Digastric, the Stylo-hyoid, Stylo-glossus, and 

 Mylo-hyoid muscles, the submaxillary ganglion, 

 the lingual and hypoglossal nerves, Wharton's 

 duct, the ranine vein, the sublingual gland, and 

 the deep portion of the submaxillary gland. 

 By its deep surface, with the Stylo-hyoid liga- 

 ment, the Genio-hyo-glossus, Lingualis, and 

 Middle constrictor, the lingual vessels, and the 

 glosso-pharyngeal nerve. 



The Chondro-glossus is a distinct muscular 

 slip, though it is sometimes described as a part 

 of the Hyo-glossus, from which, however, it is 

 separated by the fibres of the Genio-hyo-glossus, 

 which pass to the side of the pharynx. It is 

 about three-quarters to an inch in length, and 

 arises from the inner side and base of the lesser 

 cornu and contiguous portion of the body of the 

 hyoid bone, and passes directly upward to blend with the intrinsic muscular fibres 

 of the tongue, between the Hyo-glossus and Genio-hyo-glossus. A small slip of 

 muscular fibre is occasionally found, arising from the cartilage triticia in the 

 thyro-hyoid ligament, and passing upward and forward to enter the tongue with 

 the hinderrnost fibres of the Hyo-glossus. 



The Stylo-glossus, the shortest and smallest of the three styloid muscles, arises 

 from the anterior and outer side of the styloid process, near its apex, and from the 



CHONDRO-GLOSSUS. 



FIG. 205. Muscles of the tongue from be- 

 low. (From a preparation in the Museum of 

 the Royal College of Surgeons of England.) 



