Muscles of Tongue \ \ 5 



An nicer may form at the frcenum of a little child whose tongue is 

 constantly being scratched in a whooping-cough over the serrated edge 

 of his lower incisors. 



Of the papillce, the largest are the circumvallate, about ten in 

 number, arranged in two oblique rows which slope back to the foramen 

 caecum. The fungi 'form, skittle-shaped, are chiefly scattered over the 

 sides and apex of the tongue ; they are deep-red, and in scarlet fever, 

 when the tongue is coated with a yellow fur, they are conspicuous by 

 their bright colour. The filiform are arranged as a protective layer 

 over the anterior two-thirds of the dorsum. 



At the back of the tongue there are many mucous glands and 

 crypts like those in the tonsil. 



The fur upon the tongue is the result of desquamation of the 

 epithelium which is constantly taking place. When a person sleeps 

 with the mouth open the fur becomes dried by the air passing over it, 

 and the tongue gets hard and rough. 



Muscles. The genio-hyo-glossus, fan-shaped, arises from the 

 upper of the genial tubercles, and is inserted in the middle line of the 

 tongue from apex to base, into the pharynx, and into the hyoid bone. 



Action. Its anterior fibres retract the tongue, its posterior fibres 

 raise its base and help in protrusion ; they also increase the antero- 

 posterior diameter of the pharynx, and draw upwards the hyoid bone 

 and the pharynx. 



When, during operation, the muscle is detached from the maxilla, 

 the tongue is apt to fall back, and, the epiglottis sinking, suffocation 

 may ensue. 



Its nerve is the hypoglossal. When a patient under an anaesthetic 

 is breathing with stertor, his lower jaw should be raised, so that the 

 attachment of the genio-hyo-glossus may be pulled upon, and the 

 base of the tongue thereby drawn out of the pharyngeal air-way. 



Relations. -Its inner surface lies in contact with its fellow. Its 

 outer surface touches the inferior lingualis, the hyo-glossus, the 

 lingual artery and gustatory nerve, and the sublingual gland ; the 

 hypoglossal nerve enters its outer surface. Its inferior border rests 

 against the genio-hyoid, and its superior border lies just behind the 

 fraenum. 



The hyo-glossus, an oblong muscle, arises from the body and 

 cornua of the hyoid bone, and is inserted into the side of the tongue. 

 It is supplied by the hypoglossal nerve. 



Relations. Its deep surface rests against the lingualis, genio-hyo- 

 glossus, and the middle constrictor of the pharynx. The glosso- 

 pharyngeal nerve turns under its upper and posterior corner, and the 

 lingual artery runs beneath it (p. 28). Superficially, it has the tendon 

 of the posterior belly of the digastric, the stylo-hyoid, and the hypo- 

 glossal nerve ; the gustatory nerve ; the mylo-hyoid, and the deep part 

 of the submaxillary gland and its duct. 



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