1128 



TONGUE. 



and act with the greatest advantage. This 

 arrangement I shall now proceed to describe. 

 Suppose the section made at a point just 

 in front of the anterior free border of the 

 genioglossi {fig. 748.). Immediately beneath 

 the papillae (which may be very well dis- 

 played by this method), the condensed sub- 

 mucous areolar tissue or cutis of the tongue is 

 seen, of considerable thickness, being thickest 

 on the upper surface, especially towards the 

 middle(art). Immediately beneath this, around 

 the whole circumference of the tongue, is seen 

 a very curious areolated or fenestrated ap- 

 pearance, consisting of cross bars, branching 

 and interlacing irregularly at various angles, 

 leaving interspaces that are filled up by groups 

 of discs (del). The cross bars are at once seen 

 to be small fasciculi of the vertical or trans- 

 verse fibres, or both, according to the part 

 looked at, and the groups of discs are seen to 

 be transverse sections of the longitudinal 

 fibres passing through the meshes formed by 

 the vertical and transverse, which they more 

 or less completely fill, and with whose shape 

 they more or less exactly correspond (Jigs. 748. 

 and 751.)- The fasciculi of the longitudinal 

 fibres are in most situations much larger than 

 those of the vertical and transverse, among 

 which they are contained ; indeed, the lon- 

 gitudinal being confined to the surface, it 

 would naturally be expected that they would 

 preponderate there. The vertical fibres are 

 most abundant in the vertical median plane 

 and the horizontal in the horizontal median 

 plane (f), the vertical not existing near the 

 lateral surfaces, nor the transverse near the 

 superior and inferior surface (figs. 749. a, a) ; 

 and from this fact result almost all the pe- 

 culiarities of arrangement of the fibres that we 

 see. 



In the first place it results from this, that 

 the vertical and horizontal fibres cross each 

 other in the centre, which they entirely occupy, 

 and therefore exclude the longitudinal ; ac- 

 cordingly no discs are seen in the central 

 part of the tongue. Secondly, that at a cer- 

 tain line (fig. 748. g.) the vertical emerge 

 from the transverse, and are continued up 

 or down, to the superior or inferior surface, 

 alone; and similarly at the lateral regions the 

 transverse emerge from the vertical, and are 

 continued on alone to the cutis at the 

 sides ; hence the fibres near the middle of the 

 upper and under surface, and at the borders 

 of the tongue, do not interlace but pass to 

 the surface with something of parallelism; 

 and hence the fasciculi of longitudinal fibres 

 here are arranged, not as in the mesh of a 

 network, but in parallel rows at right angles 

 to the surface ; an arrangement very charac- 

 teristic of these situations. Thirdly, it would 

 result from this absence of vertical fibres at 

 the sides, and of the transverse above and 

 below, that there would be four situations 

 (b, b, b, b, fig. 749. A .) in the neutral ground 

 between the upper and under surfaces and the 

 borders respectively, where there would be no 

 cross fibres of any sort, and where the lon- 

 gitudinal fibres would exist alone, unsupported 



and unseparated. Moreover, the vertical fibres 

 at the upper and under surface, and the trans- 



Fig. 749. 



A 



a 



a 



Plan of the intrinsic muscles of the tongue as seen in 

 transverse section. 



a, a, a, a, Superior, inferior, right and left 

 lateral regions ; I, b, b, b, right and left supra and 

 sub-lateral regions. (Compare with fig. 4.). 



verse at the sides, would be so dense and 

 numerous that they would hardly admit of any 

 longitudinal fibres in their interspaces. Now 

 the support and separation of the longitudinal 

 fasciculi, and the admission of a sufficient 

 number of them at all the superficial parts of 

 the tongue (especially the two surfaces and the 

 two edges, which may be called the cardinal 

 points of the tongue with regard to its move- 

 ments), are the two things that are especially 

 to be brought about. To achieve this double 

 object, the vertical and horizontal fibres, as 

 they approach their respective surfaces, spread 

 out in a sort of fan-like manner ; the most 

 lateral of the vertical fibres spreading out to- 

 wards the sides (fig. 748. k, k), and the most 

 superior and inferior of the transverse spread- 

 ing up and down towards the surfaces (fig.l^S. 

 i, i,fi,g. 749. B.). The two sets thus cross each 

 other and fill the otherwise empty space with 

 a network of considerable regularity and beauty, 

 which is characteristic of these four situations, 

 as the parallel fasciculi at right angles to the 

 surface are characteristic of the four inter- 

 mediate ones. For the sake of convenience 

 I shall call the situations where the transverse 

 and vertical fibres approach the surface in pa- 

 rallel bundles, the superior, the inferior, and 

 the right and left lateral regions (fig. 749. A,B. 

 a, a, a, a) : those in which they decussate as 

 they approach the surface, I shall call the 

 right and left supra-lateral, and the right and 

 left sub-lateral (/g.749. B.b,b, b,b.). Fourthly, 

 the mesial vertical and mesial horizontal plane 

 are the situations where the vertical and hori- 

 zontal fibres respectively would act with the 

 greatest power on the form of the tongue, and 

 where also they would admit of being the 



