2 28 THE VISCERA. 



each, which converge near the base of the tongue so as to form 

 a V with the apex directed caudad. 



Muscles of the Tongue (Fig. 96). — M. genioglossus 

 (/) passes from the symphysis of the lower jaw into the tongue 

 and Hes beneath (dorsad of) the geniohyoid {g). 



Origin from the medial surface of the mandible near the 

 symphysis and dorsad of the origin of the geniohyoid. 



Insertion. — The fibres pass dorsad, diverging in a fan-like 

 manner and forming a flat vertical plate closely applied to the 

 muscle of the opposite side. This plate extends along the 

 caudal three-fourths of the tongue, i.e. as far as it is attached. 

 The cranial fibres arch craniad to the tip of the tongue, the 

 caudal fibres arch caudad to the root of the tongue. Dorsad 

 the muscle is confounded with the muscle of the opposite side. 



Action. — Draws the root of the tongue forward and the tip 

 backward. 



M. hyoglossus (/;). — From the body of the hyoid bone to 

 the tongue. 



Origin. — (i) From the ventral surface of the body of the 

 hyoid laterad of the geniohyoid {^g), and (2) by a second head 

 from the ceratohyal. 



Insertion. — Both heads penetrate into the tongue between 

 the styloglossus {/) and the genioglossus (/). The fibres 

 intermingle with those of the styloglossus {c) and thus help to 

 form the lateral parts of the tongue. They finally end in the 

 integument on the dorsum of the tongue at the sides. 



Action. — Retracts the tongue and depresses it. 



M. styloglossus {/). — From the stylohyal bone to the 

 tongue. 



Origin from the mastoid process of the temporal bone, from 

 the stylomandibular ligament (2) (which connects the border 

 of the external auditory meatus with the angular process of the 

 mandible) and from the proximal cartilaginous portion of the 

 cranial cornu of the hyoid bone. The fibres pass mediad, 

 diverging between those of the digastric and hyoglossus (/;) 

 into the lateral part of the tongue. 



Insertion. — The fibres pass toward the tip of the tongue, 

 where the mass finally ends in a point, the superficial ones 



