1122 



TONGUE. 



that there is formed in the median line a 

 series of angles pointing backwards. This 

 disposition is seen to affect, more or less, all 

 the structures with which the surface is 

 covered. Thirdly, the upper surface of the 

 tongue is seen to be divisible into a smooth 

 and a rough portion. The smooth, or non- 

 papillary portion, occupying nearly the pos- 

 terior third, is characterised by smooth nodular 

 rugosities (fig. 745. e), formed by small mu- 

 ciparous glands, which are abundantly dis- 

 tributed beneath the surface, and occupy the 

 whole space between the papillae and epi- 

 glottis : they are smallest and most scattered 

 behind, where they are gradually lost ; larger 

 and more prominent in front, where, from 

 their being disposed in the direction already 

 indicated, they form a prominent V-shaped 

 ridge with the opening directed forwards. 

 Just in front of this, separated by a groove, is 

 another V-shaped ridge, more definite, but 

 less constant in shape, formed by two con- 

 verging lines of button-like eminences, each 

 surrounded by a circular raised border of 

 more or less regularity ; these compound 

 organs are the circumvallate papillae {Jig. 745. 

 ff)* At the angle formed by the convergence 

 of their two rows, generally a little behind 

 that angle, is situated a cul-de-sac of very 

 variable size, which has received the name of 

 foramen ccecum (le trou borgne, lacune de la 

 langue}, and which was formerly regarded as 

 the orifice at which several convergent sali- 

 vary ducts terminated* ; these supposed sali- 

 vary ducts were : afterwards shown by Duver- 

 noy-|- and Haller.J to be merely small veins. 

 Meckel considered that this foramen caecum 

 was nothing but a largely developed calyx of 

 a caliciform papilla, of which the central 

 portion was small, or wanting, or misplaced ; 

 that if the central eminence was well de- 

 veloped and in its proper situation, the 

 foramen caecum was wanting, and that it only 

 existed from some of the irregularities above 

 mentioned; an opinion adopted by Cruveilhier, 

 and by Professors Todd and Bowman in this 

 country. Meckel states that he has seen two, 

 one a great way behind the other. I have 

 more than once met with the same appear- 

 ance. In these cases the anterior one has 

 always contained a well developed papilla. 

 It can evidently perform no essential office, as 

 it is so often wanting. The whole of the su- 

 perior surface of the tongue, in front of the 

 circumvallate papillae, comprising its anterior 

 two thirds, is covered by an investment of 

 coriaceous or filamentous asperities, longest in 

 the central parts, and arranged with the most 

 regularity at the back, where they are dis- 

 tributed in lines of more or less distinctness, 

 with a direction obliquely forwards and out- 

 wards (Jig. 745. i '.). These eminences are 

 seen to be of two sorts ; one of a spheroidal 

 shape, distinguished during life by their red 



* Coschwitz, De Ductu salivali novo. Halle, 

 1724. 



f Loc. cit. 



f Exp. et Dub. circa Ductum Coschw. Leyden, 

 1727. 



colour, and scattered here and there at the 

 posterior part, edges and tip, these are the 

 fungiform papilla (fig. 745. h.) ; the others, 

 occupying the whole of the rest of the sur- 

 face, are the conical and filiform. To the 

 minute consideration of these structures a 

 future part of this article will be devoted. 



Inferior surface. This surface is attached 

 in its posterior two thirds by the muscles 

 passing from it to the hyoid bone and lower 

 jaw. The most posterior part of this attach- 

 ment is as wide as the tongue itself, so that 

 there no portion of the inferior surface is 

 free ; but in front of this the attachment 

 narrows, so that the lateral portions become 

 increasingly free till they meet at the fraenum, 

 in front of which they involve the whole 

 surface. The longitudinal furrow is much 

 more distinctly marked here than above, and 

 is constant : it passes from the tip, on which 

 it is continued, to the fraenum. On each side 

 of the furrow the ranine veins are seen pass- 

 ing forwards, and immediately beneath the tip 

 is a little cluster of mucous glands first de- 

 scribed by Nuck*, and also by Nuhn.f The 

 mucous membrane here is quite smooth and 

 free from any visible papillae. 



The edges of the tongue, which separate 

 its upper and under surface, are thick behind 

 and gradually become thinner in front ; they 

 are marked by a series of vertical ridges, 

 separated by corresponding furrows, very dis- 

 tinct on the upper, and gradually becoming 

 lost as they approach the under, surface. 

 They are very conspicuous at the posterior 

 part, but disappear anteriorly, and they differ 

 very much in their development in different 

 subjects. They are, essentially, fused conical 

 papillae. At the upper and posterior part of 

 the edges are also a series of small mucous 

 glands. 



The anterior extremity, apex, or point (fig. 

 745. b.), is flattened or rounded, blunt or 

 pointed, according to the movements of the 

 tongue, and slightly impressed by the median 

 furrow which is continued on it : it is not 

 marked by any of those vertical ridges that 

 characterise the edges. 



The posterior extremity, or base. Ere the 

 tongue reaches the os hyoides it becomes very 

 flat and thin, and this from two causes di- 

 minution in the quantity of the intrinsic mus- 

 cles, and the passing off of the extrinsic in 

 other directions ; so that instead of being 

 very thick, as is generally described, the base 

 is in reality the thinnest part of the whole 

 organ. It is flattened antero-posteriorly and 

 much extended laterally, and by its attach- 

 ment to the hyoid bone is curved in a horse- 

 shoe shape, which, however, is much effaced by 

 the insertion of the epiglottis in the area of 

 the curvature. It is constituted laterally by 

 the hyoglossi, centrally by the hyoglossal liga- 

 ment, anteriorly by some fibres of the genio- 

 glossus, and behind and above by the mu- 

 cous membrane passing from it over the 



* Sialographia, Ductuum aquosorum anatome 

 nova. Leyden, 1690. 



f See Art SALIVARY GLANDS, p. 426. 



