54 ANTHROPOLOGY. 



serted into a rougli depression on tlie inner side of the base of the jaw close 

 to the symphysis. Its median tendinous portion passes through the stylo- 

 hyoid muscle, and is connected with the corner of the hyoid bone by a dense 

 fascia, and sometimes by a tendinous ring like a pulley. Its use is to de- 

 press the lower jaw, and when the mouth is closed to elevate the os hyoides, 

 tongue, and larynx. 



The mylo-hyoideus is a triangular muscle, arising from the myloid ridge on 

 the inner surface of the sides of the maxilla, which line descends obliquely 

 from the last molar tooth towards the chin : it is inserted into the base of 

 the OS hyoides. Use : to elevate the os hyoides and tongue, so as to press 

 the latter against the palate. 



The genio-hyoideibs, short and round, arises by a small tendon on the inner 

 side of the chin, above the digastric, and descending, is inserted into the 

 base of the os hyoides. Its use is to draw the os hyoides upwards and for- 

 wards, to push the tongue against the incisor teeth, or to protrude it from 

 the mouth. 



The hyo-glossus is flat and thin, arising from the corner and part of the 

 body of the os hyoides, and being inserted into the side of the tongue. 

 Use : to render the dorsum of the tongue convex by depressing its side ; it 

 may also elevate the os hyoides and base of the tongue. 



The genio-hyo-glossus is triangular or fan-shaped : it arises by a small 

 tendon from an eminence inside the chin beneath the fraänum linguse : the 

 insertion is into the mesial line of the tongue from the apex to the base, 

 and into the body or lesser corner of the os hyoides. This muscle is of 

 importance in mastication and deglutition, as also in the articulation of 

 certain letters. 



Lingualis is a fasciculus of fibres taking a longitudinal course on the 

 inferior surface of the tongue from the base to the apex ; its use is to 

 shorten the tongue and bend the tip downwards and to one side. 



Stylo-hyoideus arises from the outer side of the styloid process near its 

 base, and is inserted into the cornu and body of the os hyoides. It co- 

 operates with the digastric in raising and drawing back the os hyoides and 

 tongue. 



Stylo-glossus arises from the inner side of the styloid process near its point, 

 and is inserted into the side of the tongue. It draws the tongue backwards 

 and to ofte side, and raises the tip behind the upper incisors. 



Styh-pharyngeus arises from the back part of the root of the styloid pro- 

 «'.ess, and is inserted into the side of the pharynx, also into the corner of 

 the OS hyoides and thyroid cartilage. It elevates and dilates the pharynx 

 so as to receive the food from the tongue. 



Longus colli, the first of the deep layer of the muscles of the neck, 

 extends from the third dorsal vertebra to the atlas : it arises from the sides 

 of the bodies of the three superior dorsal and four inferior cervical vertebrae, 

 from the intervertebral ligaments, also from the head of the first rib and 

 from the anterior tubercles of the transverse processes of the last four 

 cervical vertebras. The fibres ascend obliquely, adhering to each bone in 

 their course, and are inserted into the fore part of the first, second, and 

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