THE MOUTH. 401 



Situation of the tongue. — The tongue occupies the whole length of this 

 elongated cavity, and thus extends from the back part of the mouth to the 

 incisor teeth, lying in the intermaxillary space, where it rests on a kind of 

 wide sling formed by the union of the two mylo-hyoidean muscles (see Fig. 

 307, 7). 



External conformation. — It is a fleshy organ, movable in the interior of the 

 buccal cavity, and almost entirely enveloped by the mucous membrane which 

 lines that cavity. In Solipeds, it forms a kind of triangular pyramid, flattened 

 on each side, fixed to the os hyoides and the inferior maxilla by the muscles 

 which form the basis of its structure, or by the membrane that covers the 

 organ. 



Its form permits it to be divided, for the study of its exterior, into three faces, 

 three borders, and two extremities. 



The superior face, or dorsum of the tongue, narrower in front than behind, 

 is roughened by numerous papilla which give it a downy aspect. Two of these 

 papillae are remarkable for their enormous volume, their lobulated appearance, 

 and the situation they occupy at the bottom of two excavations placed side by 

 side, near the base of the organ — the lingual lacunce, or foramen ccecum of Mor- 

 gagni. This face corresponds to the palatine arch or roof, when the jaws are 

 together. The lateral faces, wider in the middle of the tongue than at its 

 extremities, are limited by the internal surfaces of the inferior maxillary branches. 

 On them are seen several large papillse, and the orifices of the lingual glandulce. 



These two faces are separated from the former by two lateral borders, which 

 correspond to the superior alveolar arches when the mouth is exactly closed. 

 "With regard to the third or infeiior border, its existence may be said to be 

 fictitious ; by it enter the muscles which constitute the substance of the tongue, 

 and it is by it, also, that the organ is fixed at the bottom of the intermaxillary 

 space. 



The posterior extremitg, or base of the tongue, is limited, in the interior of 

 the mouth, by a furrow which borders the base of the epiglottis. It presents 

 a thick, median, mucous fold, plaited in difl'erent ways, and carried over the 

 anterior aspect of the epiglottic cartilage. Two other folds, more anterior, also 

 formed by the buccal membrane, unite with the soft palate on each side of the 

 base of the tongue ; these are the posterior pillars of the organ (or the glosso- 

 epiglottic ligaments of Man), and comprise in their substance a voluminous 

 collection of glands. Behind these pillars are two triangular spaces, included 

 between the velum pendulum palati and the base of the tongue, each of which 

 has an excavation perforated with openings — a veritable amygdaloid cavity — which 

 represents the amygdalce (tonsils) of Man and the Carnivora ; it is a kind of 

 common confluent for the numerous glandulae accumulated outside the mucous 

 membrane that lines this excavation. 



The anterior extremity of the tongue is quite free, from the middle of the 

 interdental space, and moves at liberty in the interior of the buccal cavity : it is 

 also termed the free portion of the tongue, in distinction to the remainder of 

 the organ, which is named the fixed portion. This free portion is flattened 

 above and below, and slightly widened or spatulated. Its superior face is 

 plane, or nearly so, and prolongs that of the fixed portion. The inferior, 

 slightly convex, and perfectly smooth, is continuous with the lateral faces of 

 the organ, and rests on the body of the inferior maxilla ; it is fixed to that bone 

 by a median fold of mucous membrane — the anterior pillar, or frcBuum lingvm. 



