186 



MUSCLES OF THE HEAD AND NECK. 



a short tendon from the superior genial tubercle behind the symphysis of 

 the jaw : from this its fibres diverge and are inserted in an extensive range, 

 viz., those which are most inferior into the body of the hyoid bone, and a 

 few into the side of the pharynx ; those which are most superior into the 

 tip of the tongue ; and the intermediate fibres into its whole length, 

 diverging transversely in its substance. 



The external surface is in contact with the lingualis inferior, hyo-glossus and stylo- 

 glossus muscles, the sublingual gland, the ranine vessels, and the nerves of the tongue. 



Fig. 162. 



Fig. 162. SKETCH OP A PART 

 OF THF LEFT SIDE OF THE 

 SKULL, THE RIGHT SIDE OF 

 THE BODY OF THE LOWER JAW, 

 AND THE TONGUE, HYOID 

 BONE, LARYNX, AND TRACHEA, 

 SHOWING THE EXTRINSIC 

 MUSCLES OF THE TONGUE, 

 &o. 4 



a, external pterygoid pro- 

 cess ; b, styloid process ; c, 

 section of the symphysis of the 

 lower jaw; d, front of the 

 body of the hyoid bone ; c, 

 hyoid cartilage ; /, front of the 

 cricoid cartilage ; between d 

 and e, the thyro-hyoid mem- 

 brane and ligament ; g, isthmus 

 of the thyroid gland in front 

 of the trachea; 1, left stylo- 

 glossus muscle ; 2, stylo-hyoid ; 

 3, stylo-pharyngeus ; 4, cut 

 edge of the mylo-hyoid ; 5, 

 genio-hyoid ; 6, genio-hyo-glos- 

 sus; 7, hyo-glossus; 8, lingua- 

 lis inferior ; 9, part of the supe- 

 rior constrictor of the pharynx ; 

 10, back part of the middle 

 constrictor; 11, inferior con- 

 strictor ; 12, upper part of the 

 oesophagus; 13, crico-thyroid 

 muscle. 



The hyo-glossus is a flat 

 quadrate muscle, arising 

 from the whole length of 



the great cornu of the hyoid bone, from the lateral part of the body of that 

 bone, and from the small cornu ; the fibres arising from those three sources 

 (formerly distinguished as cerato-glossus, basio-glossus, and chondro-glossus 

 respectively Albums) pass upwards to be inserted into the side of the 

 tongue, blended with the stylo-glossus and palato-glossus muscles. 



The hyo-glossus is concealed by the digastric and mylo-hyoid muscles, except at its 

 posterior inferior angle : the deep part of the submaxillary gland rests on its surface, 

 and it is crossed from below upwards by the hypoglossal nerve, the Whartonian duct, 

 and the gustatory nerve, It covers the genio-gloseus and the origin of the middle 

 constrictor of the pharynx, together with the lingual artery and glosso-pharyngeal 



The stylo- glossus, the shortest of the three muscles which spring from the 

 styloid process, arises from that process not far from its point, and from the 



