THE MOUTH 335 



depressed from side to side, fixed to the os hyoides and the inferior maxilla 

 by the muscles which form the basis of its structure, or by the tegumentary 

 membrane which covers the organ. 



Its form permits it to be divided, for the study of its external disposition, 

 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 papillae 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 ; they are named the lingual 

 lacunse, or foramen csecum of Morgagni. This face responds 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 maxillary branches. Onthem are seen several large papillae, 

 and the orifices of some lingual glandules. 



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 inferior 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 extremity, 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 different 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 the base of the tongue ; these are the posterior pillars of the organ 

 (or the glosso-epiglottic ligaments of Man), and comprise in their thick- 

 ness 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 open- 

 ings, a veritable amygdaloid cavity, which represents the amygdalae (tonsils) 

 of Man and the Carnivora ; it is a kind of common confluent for the 

 numerous glandulae accumulated outside the mucous membrane which lines 

 this excavation. 



The anterior extremity of the tongue is quite independent from the 

 middle of the interdental space, and moves freely in the interior of the buccal 

 cavity : it is also termed the free portion of the tongue, in opposition 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 maxillary bone ; it is 

 fixed to that bone by a median fold of mucous membrane, the anterior pillar, 

 orfrsenum linguce. The borders, in joining each other in front, describe a 

 parabolic curve which is in contact with the incisive arches. 



STRUCTURE. The tongue offers for study, in regard to its structure : 

 1, The mucous membrane enveloping the organ; 2, The muscular tissue which, 

 in reality, forms its mass ; 3, The vessels and nerves distributed to it. 



1. Mucous membrane. This membrane, a continuation of that lining the 

 mouth, is folded at the bottom of the canal on the sides of the tongue, covers 

 the upper surface of the organ, and envelops the whole of its free portion. 

 Its derm or corium has not the same thickness throughout, but is in com- 



