MUSCLES BETWEEN THE JAW AND OS HYOIDES. 317 



Inserted into the surface of the rough line at the external part 

 of the inferior edge of the thyroid cartilage. 

 Use. To draw the larynx downwards. 



2. Thyro-Hyoideus, 



Arises from the rough line opposite to the insertion of the 

 former muscle. 



Inserted into part of the basis, and almost all the cornu of 

 the os hyoides. 



Use. To pull the os hyoides downwards, or the thyroid car- 

 tilage upwards. 



3. Crico-Thyroideus , 

 Which will be described with the larynx : Chap. xiv. 



Muscles situated between the Lower Jaw and Os Hyoides 



laterally. 



They are five in number. They proceed three from the styloid 

 process of the temporal bone, from which they have half of 

 their names ; and two from the pterygoid process of the sphe- 

 noid bone. 



The three from the styloid process are, 



1 . Stylo-Glossusj 



Arises, tendinous and fleshy, from the styloid process, and 

 from a ligament that connects that process to the angle of the 

 lower jaw. 



Inserted into the root of the tongue, runs along its side, and is 

 insensibly lost near its apex. 



Use. To draw the tongue laterally and backwards. 



2. Stylo- Hyoideusj 



Arises, by a round tendon, from the middle and inferior part 

 of the styloid process. 



Inserted into the os hyoides at the junction of the base and 

 cornu. 



Use. To pull the os hyoides to one side, and a little upwards 

 27* 



