282 SPLANCHNOLOGY. 



HYO-GLOSSUS LONGUS. 



(Stylo-glossus.) 



(Fro. 90. b b.) 



Situated along the border of the tongue, this muscle is long 

 and flat. 



Origin. From the external surface of the cornu of the os 

 hyoides. 



Insertion. To the substance of the tongue expanding towards 

 the tip. 



Relation. Externally with the mylo-hyoideus and sublingual 

 gland, sublingual nerve, and canal of Wharton ; internally with 

 the genio-hyo-glossus and hyo-glossus brevis. 



Action. With its fellow to retract the tongue within the 

 mouth ; singly, to draw it to one side. 



HYO-GLOSSUS BREVIS. 



(Basio-glossus.) 



(FiG. 90. c.) 



Situated on the inner surface of the hyo-glossus longus, it is 

 a broad, flat, and somewhat radiating muscle, the fibres passing 

 obliquely forwards and upwards. 



Origin. From the side of the body and spur process of the os 

 hyoides and the inferior part of the cornu. 



Insertion. The side of the tongue, passing inwards to form 

 the " transverse fibres." 



Relation. Externally with the mylo-hyoideus and hyo-glossus 

 longus, the hypoglossal nerve, Wharton's canal, and the mucous 

 membrane of the tongue ; internally with the hyoideus parvus 

 and the corniculum, genio-hyo-glossus, the lingual artery, and the 

 glosso-pharyngeal nerve. 



Action. To draw the base of the tongue downwards and back- 

 wards, on one side, or both if acting with its fellow. 



HYO-GLOSSUS PARVUS. 



Situated immediately under the mucous membrane, intimately 

 blended with the last-named, this is a small radiating muscle. 



Attachments. It arises from the inner aspect of the corniculum 

 and hyoid bone, crosses the hyoideus transversus, its fibres then 

 running forwards. It expands over the dorsum and sides of the 

 tongue, its fibres crossing those of the hyo-glossus brevis. 



