172 MYOLOGY. 



Insertion. — To a small tubercle on the heel process of the os 

 hyoides. 



Relation. — Externally with the pterygoid muscle ; internally 

 with the pharynx, guttural pouch, and hypoglossal nerve ; the 

 glosso-facial artery and glosso-pharyngeal nerve pass between it 

 and the cornu. The anterior tendon forms a ring through which 

 plays the middle tendon of the digastricus. 



Action. — It draws the body of the os hyoides backwards and 

 upwards, thus antagonising the preceding muscle ; it also assists 

 in dilating the glottis. 



HYOIDEUS PARVUS. 

 [Kerato-hyoideus Parmis. ) 



Situated above and before the preceding muscle, it is small, 

 flat, and triangular. 



Origin. — From the inferior border of the anterior extremity 

 of the cornu, and the posterior border of the corniculum. 



Insertion. — To the body and heel process of the os hyoides, 

 filling up the space between the three bones. 



Relation. — Externally with the hyo-glossu-s and the lingual 

 arteries ; internally with the mucous membrane. 



Action. — It approximates the three bones to which it is 

 attached. 



HYOIDEUS TRANSVERSUS. 



A short, thin muscle, joining the cornicula together by their 

 superior extremities, which on contraction it approximates. 



STYLO-HYOIDEUS. 



(Fig. 71. /.) 



Flat and triangular, it fills up the space between the posterior 

 part of the angle of the cornu, and the styloid process of the 

 occipital bone. 



Origin. — The anterior border of the styloid process. 



Insertion. — The posterior part of the cornu. 



Relation. — Externally with the parotid gland, and internally 

 wdth the guttural pouch. Its posterior fibres blend wdth those of 

 the origin of the digastricus. 



Action. — It draws back and depresses the os hyoides, and 

 tongue. 



