ORGANS OF DEGLUTITION. 305 



and fully exposed on removing the anterior belly of the 

 digastric. It arises from the myloid ridge on the inner 

 side of the lower jaw, and descends inwards and backwards 

 to be inserted into the base of the os-hyoides, and along 

 with its fellow into the middle tendinous line, between 

 that bone and the chin. 



Function. To bring the os-hyoides forward and pro- 

 ject the tongue. This muscle is covered by the digastric 

 muscle, the submaxillary gland, the platysma and fascia, 

 and lies upon the genio-hyoid, hyo-glossus, and stylo- 

 glossus muscles the duct of Wharton, lingual and gus- 

 tatory nerves, and sublingual gland. 



Eemove this muscle by dividing it on either side, and we 

 see the next in order, i. e. Genio-hyoideus , (ysvswv, the chin,) 

 Fig. 8*7- It arises from the posterior mental tubercle above 

 the digastric, by a small tendon, and descends backward to 

 be inserted into the base of the os-hyoides. Function. To 

 bring the os-hyoides forward, and to protrude the tongue 

 against the incisor teeth, or out of the mouth. 



Genio-Jiyo-glossus , 



(yxwtfora, the tongue,) is 

 seen by removing the 

 genio-hyoideus. It is a' 

 triangular muscle_, and 

 arises by a small tendon 

 from the posterior men-l 

 tal tubercle, above the 

 genio-hyoideus and be- 

 low the frenum linguae, 

 and is inserted into the 

 tongue along the mesial 

 line its whole length, 

 and into the body of the 

 os-hyoides. Its fibres radiate in different directions; some 



FIG. 87 represents a side view of the Tongue and its principal Muscles. 

 1 Mastoid process. 2 Coronoid process. 3 Stylo-glossus muscle. 4 Hyo- 

 glossus. 5 Genio-hyo-glossus. 6 Genio-hyoideus. 7 Symphysis menti. 8 

 Styloid process. 



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