226 THE MUSCLES. 



of the head, thinner and narrower below than above, and formed entirely of 

 fleshy fibres which extend transversely from its anterior to its posterior 

 border. Inferiorly, it is composed of a small fasciculus, which is 

 distinguished from the principal portion by the slightly different direction 

 of its fibres, and which covers in part the external surface of the muscle. 



Fig. Ill 



HYOIDEAL AND PHARYNGEAL REGIONS. 



1, Neck of inferior maxilla ; 2, Hard palate ; 3, Molar teeth ; 4, Buccal membrane ; 5, 

 Submaxillary glands; 6, Soft palate; 7, Tendon of hyoideus magnus through 

 which the tendon, 8, of che digastricus passes ; 9, Lower portion of digastricus ; 

 10, Stylo-hyoideus ; 11, Buccal nerve; 12, Zygomatic arch , 13, Orbital branch 

 of fifth pair of nerves ; 14, Articular process of temporal bone ; 15, Right cornu of 

 hyoid bone ; 16, Hyo-glossus longus, or Kerato-glossus ; 17, Lingual nerve ; 18, 18, 

 Tongue ; 19, Angle of left branch, of inferior maxilla ; 20, Submaxillary gland, 

 left side ; 21, Subscapulo-hyoideus ; 22, Great hypoglossal nerve ; 23, Hyc- 

 thyroideus ; 24, Sterno-hyoideus ; 25, Sterno-thyroideus ; 26, Subscapulo hyoi- 

 deus ; 27, Thyroid gland ; 28, External carotid artery ; 29, Pneumogastric nerve ; 

 30, Stylo-hyoideus ; 31, Genio-hyoideus. 



Attachments. It originates from the mylo-hyoid line by the anterior 

 extremities of its fibres. Its movable insertion takes place on the inferior 

 face of the hyoid body, on its anterior appendix, and on a fibrous raphe which 

 extends from the free extremity of this appendix to near the genial surface, 

 and which unites, on the median line, the two mylo-hyoidean muscles. 



Relations. By its external face, with the inferior maxilla, the digastric 

 muscle, and the Submaxillary lymphatic glands, By its internal face, with 

 the sublingual gland, the Whartonian duct, the hypoglossal and lingual 

 nerves, the genio-glossus, hyo-glossus longus and brevis, and genio-hyoideus. 

 Its superior border responds to the internal pterygoid. 



Action. In uniting on the median line with that of the opposite side, 

 this muscle forms a kind of wide band or brace on which the tongue rests. 

 When it contracts, it elevates this organ, or rather applies it against the 

 palate. 



2. Genio-hyoideus. 



Form Structure Situation. A fleshy, elongated, and fusiform body, 

 tendinous at its extremities, but especially at the inferior one, and applied, 

 with its fellow of the opposite side, to the mylo-hyoidean brace. 



