338 MUSCLES AND FASCIAE. 



Digastric, the Mylo-hyoid, and Genio-hyoid muscles. In the second act, when 

 the mass is passing through the pharynx, the direct elevation of the hyoid bone 

 takes place by the combined action of all the muscles; and after the food has 

 passed, the hyoid bone is carried upwards and backwards by the posterior belly 

 of the Digastric and Stylo- hyoid muscles, which assist in preventing the return 

 of the morsel into the mouth. 



4. LIN.GUAL EEGION. 



Genio-hyo-glossus. Lingualis. 



Hyo-glossus. Stylo-glossus. 



Palato-glossus. 



Dissection. After completing the dissection of the preceding muscles, saw through the lower 

 jaw just external to the symphysis. Then draw the tongue forwards, and attach it, by a stitch, 

 to the nose ; and its muscles, which are thus put on the stretch, may be examined. 



The Genio-hyo-glossus has received its name from its triple attachment to the 

 chin, hyoid bone, and tongue ; it is a thin, flat, triangular muscle, placed ver- 

 tically on either side of the middle line, its apex corresponding with its point 

 of attachment to the lower jaw, its base with its insertion into the tongue and 

 hyoid bone. It arises by a short tendon from the superior genial tubercle on 

 the inner side of the symphysis of the chin, immediately above the Genio- 

 hyoid; from this point, the muscle spreads out in a fan-like form, the inferior 

 fibres passing downwards, to be inserted into the upper part of the body of the 



Fig. 222. Muscles of the Tongue. Left Side. 



hyoid bone, a few being continued into the side of the pharynx ; the middle 

 fibres passing backwards, and the superior ones upwards and forwards, to be 

 attached to the whole length of the under surface of the tongue, from the base 

 to the apex. 



