THE TONGUE. 79 



tongue is called its root, and the anterior the point or tip. 

 Its upper surface or back, and a part of its edges, are covered 

 over with papilla, which are divided into conical, fungiform, 

 and cup-shaped papillae. Its lower surface is free for about 

 one-third of its length anteriorly : at the point of attachment 

 we observe a mucous fold called the frcenum lingua or bridle 

 of the tongue. Its two posterior thirds receive the muscles 

 which fasten it to the neighbouring parts. The base or root 

 of the tongue is fixed to the hyoid bone, an osseous semi- 

 circle bifurcated at its extremities, placed between the tongue 

 and the larynx, and bound to these two organs by muscles, 

 which gives unity to their movements in rising and falling. 

 The tongue is formed of muscles, some of which are proper 

 to itself, and others attach it to the hyoid bone, to the lower 

 jaw, and to the styloid process of the temporal bone. All 

 these muscles interlace their fibres in an inextricable manner, 

 especially towards the upper portion of the tongue. At the 

 median line and in the centre they are fixed to a cartila- 

 ginous plate, a sort of indirect prolongation of the hyoid 

 bone, which gives greater solidity to the whole. The buccal 

 mucous membrane covers the tongue, and is remarkably 

 dense on its dorsal face. 



The complex interlacement of the muscular fibres of the 

 tongue permits a great variety of motion. It can raise or 

 lower itself, lengthen or shorten, shrink or expand, diminish 

 the end to a point, bend itself upwards and downwards, hollow 

 itself into a canal lengthwise or breadthwise, carry its point 

 and its edges to the parts of the mouth into which mastica- 

 tion has dispersed the food ; in short, it exhibits in its move- 

 ments and changes of form great force and the most subtle 

 dexterity. 



The tongue receives three nerves; the great hypoglossal, 

 the lingual, and glosso-pharyngeal ; the first gives motion, and 

 the last two are the sensitive nerves of taste. Under the 

 influence of the first it takes part in the functions of diges- 

 tion and in the articulation of sounds, and endowed by the 

 others with a special sensibility, it is the principal organ 

 of taste. 



The bottom of the buccal cavity communicates with the 



