TONGUE. 



1121 



terior surface of the epiglottis, the sides of the 

 pharynx, and upwards to the soft palate and 

 posterior parts of the cheeks. As we proceed 

 forwards we find it investing the sides, and 

 gradually more and more of the under surface, 

 reflected thence over the hyoglossi and ge- 

 nioglossi muscles, the sublingual glands, 

 vessels, and nerves, and much areolar tissue, 

 which separate it from the mylohyoid muscle, 

 to the inner surface of the alveoli of the lower 

 jaw, where it becomes continuous with the 

 mucous membrane covering the gums. 



At certain points where this membrane 

 leaves the tongue it forms distinct folds, which, 

 from their being constant, have received par- 

 ticular names, and which act to a certain ex- 

 tent as ligaments orfrena of the tongue, not so 

 much by virtue of their being folds of mucous 

 membrane, as from their containing within 

 their reduplications a certain amount of a 

 more or less unyielding tissue ; in some this 

 tissue is a mixture of white and yellow fibre, 

 in others it is muscle. 



Of the first sort are three folds, a middle 

 and two lateral, passing from the base of the 

 tongue to the epiglottis, called the glosso- 

 eplglottid folds, of which the central, which is 

 always present, and has been called the pos- 

 terior free num of the tongue, and frcenum epi- 

 glottidis, is much the most considerable (fig. 

 745. d.) : they serve rather to check the move- 

 ments of the epiglottis than as lingual liga- 

 ments. From the sides of the base of the 

 tongue, passing thence to the soft palate, are 

 seen four more folds, two on each side, which, 

 from their position, have been called the 

 pillars of the fauces. They are formed by the 

 raising of the mucous membrane from the 

 general surface by two muscles: the posterior, 

 the least considerable, by the palato-pharyn- 

 geus ; the anterior, more marked, by the 

 palatoglossus. The interval between these 

 two is called the amygdaloid fossa, from its 

 being occupied by the amygdalae, or tonsils : 

 the anterior pair taken together constitute the 

 constrictor of the fauces, and the narrowing 

 caused by the whole apparatus has received 

 the name of the iathmus faucium. From the 

 basis of these folds being muscular their pro- 

 minence is liable to constant variety. But 

 the most considerable of these folds, which is 

 called, par excellence, ihefrcenum of the tongue 

 (frcenum, frenulum linguce), is placed beneath 

 the anterior free extremity, which it connects 

 with the lower jaw. It consists of a prolonga- 

 tion forwards, beyond the free border of the 

 genioglossi, of the median fibrous lamina, which 

 raises into a prominent fold the mucous 

 membrane passing from the under surface of 

 the anterior part of the tongue to the neigh- 

 bouring alveoli of the lower jaw : it forms 

 a strong ligament, and limits the backward 

 movement of the anterior extremity of the 

 tongue. Sometimes an extreme shortness 

 of this ligament is a congenital malformation, 

 preventing the free movement of the organ, 

 and so impairing speech, mastication, &c., as 

 to necessitate the operation known as cutting 

 the tongue. 



VOL. IV. 



Before entering into the specialities of the 

 anatomy of the tongue, let us examine its 



Fig. 745. 



I 



Human tongue viewed on the upper surface or 

 dorsum. (After Scemmering,') 



general configuration and external characters, 

 taking its surfaces, extremities, &c., in the 

 order above enunciated. 



Superior surface. On regarding the upper 

 surface of the tongue, we see first that it is 

 divided into two symmetrical portions by a 

 median longitudinal furrow (Jig. 745. c.), com- 

 mencing at the tip, and extending back about 

 two thirds the length of the organ. It is 

 superficial when present, but in many cases 

 does not. exist : it is the representative, in this 

 part, of that median line which symmetrically 

 divides all those organs of animal life that are 

 situated in the middle vertical plane. It is 

 very generally, but very incorrectly, stated* 

 that this furrow terminates posteriorly in the 

 foramen caecum. The two have no relation ; 

 the one often exists without the other ; and 

 in ever}' case that I have seen, the foramen 

 has been separated from the posterior ter- 

 mination of the furrow by the ridge of the 

 circumvallate papillae, sometimes by a long 

 interval. This median furrow seems partly 

 formed by the action of muscles, and partly 

 by a deficiency of papillae. Another con- 

 spicuous character of the upper surface is, 

 that the roughnesses with which it is covered 

 are arranged in lines (fig. 745.), with a 

 direction obliquely forwards and outwards, so 



* Bichat, Traite d' Anatomic, t. ii. p. 594. 

 4 c 



