274 



DIGESTIVE ORGANS. 



[sect. 131, 



structure of the organ, it is seen that the proper lingual substance 

 possesses essentially only three orders of muscular fibres, which 

 may be designated perpendicular, transverse and longitudinal. 

 The perpendicular fibres come from the genio-glossus in the 

 middle, from the lingualis and hyo-glossus laterally, at the apex 

 also from the perpendicularis, and form, from the tip to the root, a 

 large number of transverse lamellse, occupying nearly the breadth 

 of the two halves of the tongue, and whose fibres generally pass 

 perpendicularly from the under surface to the upper. The trans- 

 verse fibres of the transversus, and, in part, of the stylo-glossus, are 

 interposed as somewhat thicker laruellse between the above-men- 

 tioned, beginning at the septum and terminating at the lateral 

 border and in part at the surface. Lastly, the longitudinal fibres 

 belong to the lingualis superior {chondro-glossus) , the lingualis 

 inferior and stylo-glossus ; they cover the upper surface, the border 

 and part of the lower surface, and mostly lie immediately beneath 

 the mucous membrane. The individual muscular layers of the 

 tongue are invariably separated from each other by a thin perimy- 

 sium, and partly, where larger vessels and nerves exist, by thicker 

 rig. 112. layers of areolar tissue ; in their interstices, 



moreover, they contain, in many places, a 

 larger or smaller number of fat-cells, which 

 accumulate in considerable numbers, espe- 

 cially between the genio-glossi, at the septum, 

 at the root of the tongue, and beneath the 

 mucous membrane. 



In the tongue of the frog, there exist, as first 

 described by Dr. Waller, very beautiful divisions of 

 the transversely striped fibres (fig. 119). Although 

 I have not been able to discover with certainty any- 

 thing of the kind in the human tongue, still it has 

 appeared to me occasionally, as if some of the 

 fibres of the genio-glossus divide, shortly before 

 their transition into the tendinous bands. The 

 muscles of the tongue of the frog terminate in the 

 mucous membrane and in the papillae. 



§ 131. The mucous membrane on the 



dorsum of the tongue, from the foramen 



caecum to the tip, deviates from the remain- 



cuiar fibre of 0018'' from the i n „ mucous membrane of the oral cavity in 



tongue of the trog. Magnmed o •> 



350 times - this respect, that it is very firmly connected 



with the muscular substance, and is covered with numerous pro- 



A branch of primitive mus- 



