MUSCLES OF THE HEAD. 227 



Attachments. By its inferior extremity it is fixed to the genial surface 

 - ; by its superior, it reaches the free extremity of the anterior appendix 

 of the hyoid body t< miliniliun. 



l{i-l<tfi'iix. Outwards and downwards, with the mylo-hyoideus ; inwards, 

 with its fellow, which is parallel to it: above, with the genio-glossus. 



Act imi. It draws the hyoid bone towards the anterior and inferior part 

 of the intermaxillary space. 



3. Stylo-hyoideus. 

 (Synonyms. The hyoideus ntaynus o/Percivall. The lierato-hyoideus magnusof Leyh.) 



Structure Sit nation Direction. Thin and fusiform, this 



muscle, smaller than the preceding, and, like it, tendinous at both its 



:;ities, is situated on the side of the laryngo-pharyngeal apparatus and 



;titturul poueh, behind the large branch of the hyoid bone, whose 



direction it tollims. 



AtfncliiiK at*. Above, to the superior and posterior angle of the styloid 

 bone yiV< /<; below, to the base of the cornu of the os hyoides 



movable insertion. 



I!' In finng. Outwards, with the pterygoideus internus; inwards, with 

 the guttural pouch, the pharynx, and hypoglossal nerve. Its anterior 

 b. i nler is separated from the posterior border of the styloid bone by the 

 glosso-facial artery and glosso-pharyngeal nerve ; along the posterior 

 r lies the upper belly of the digastricus. Its inferior tendon is 

 perforated by a ring for the passage of the cord intermediate to the two 

 portions of the latter muscle. 



Action. It is antagonistic to the preceding muscle, drawing the body of 

 the hyoid bone backwards and upwards. 



4. Kerato-hyoideus. 



. This is the hyoideus parvtu of Percivall, and the tmatt kerato-hyoidetu of 



A very small fasciculus, triangular in shape, and flattened on both sides. 



'< one side, into the posterior border of the styloid cornu and the 



interior extremity of the styloid bone; and on the other, to the superior 



Inirder of the thyroid cornu. It responds, outwardly, to the basio-glossus 



and the lin^iinl artery; inwardly, to the buccal mucous membrane. 



It approximates the cornua of the os hyoides to each other. 



5. Orrijiitn xfi/lnitl, //>. 



nyin$. This is the muscle which, up to the present time, has been described by 

 .ary aiiatmi.-ts as the stylo-hyoideus. Thin name has been -.riven to the niiucle 

 ;r;inl th< hrato-hyoideut magiiut. 



A small, flat, and triangular muscle like the preceding, yet thicker and 



lid, filling the space comprised between the styloid process of the 



A:i\ mid the ln.ri/oiital portion of the posterior border of the styloid 



. Its fasciculi become longer as they are situated posteriorly, are 



nitlier tendinous, and are carried from one of these bones to the other. 



.inlly. it responds to the parotid gland; inwardly, to the guttural 



jMiuch, which it covers for its whole extent; its posterior border is largely 



< -out'.. muled with the superior insertion of the digastricns. When this 



:i--t-. it causes the os hyoides to swing, carrying its inferior extremity 



backwards and downwards. 



Q 2 



