LINGUAL MUSCLES. 283 



GENIO-HYO-GLOSSUS 



(Genio-glossus.) 

 (Fig. 90. d.) 



Situated in the vertical median plane of the tongue, this is a 

 broad, thin, and fan-shaped muscle, its fibres radiating upwards. 



Attachments. — Its basis may be said to stretch from the hyoid 

 bone to near the maxillary symphysis, the radiating fibres passing 

 upwards and some backwards, some forwards, buried in the sub- 

 stance of the tongue. 



Relation. — Internally with its fellow ; inferiorly with the genio- 

 hyoideus ; externally with the hyo-glossus longus and brevis, the 

 sublingual gland, and the lingual artery. The anterior borders 

 of this pair of muscles help to form the frsenum lingnse. Poste- 

 riorly a certain amount of fat constantly occurs between them. 



Action. — This varies. It may protrude the tongue by depress- 

 ing the dorsum, or help to retract it ; or it may depress the entire 

 organ, according to the part of the muscle which acts, and to 

 co-operation of the other muscles, 



PHARYNGO-GLOSSUS. 



This name has been applied to a few fibres which unite the 

 tongue to the lateral wall of the pharynx, passing between the 

 fibres of the genio-hyo-glossus and hyo-glossus parvus, and blend- 

 ing with them, 



PALATO-GLOSSUS. 



(See muscles of the soft palate.) 



The intrinsic muscles are collectively described under the 

 name 



LINGUALIS. 

 (Fig. 90. a.) 



This muscle is arranged in two layers of locgitudinal, with an 

 intervening set of transverse, fibres. The lingualis superficialis 

 lies on the upper surface of the tongue just below the mucous 

 membrane, running longitudinally from the apex nearly to the 

 OS hyoides. The lingualis inferior, also longitudinal in direc- 



