INTRINSIC MUSCLES OF THE TONGUE. 811 



terval between the upper and lower longitudinal muscles, and they are inter- 

 woven extensively with the other muscular fibres. Passing outwards from the 

 median plane, where they take origin from a fibrous septum, they reach the 

 dorsum and borders of the tongue. In proceeding outwards, they separate, 

 and the superior fibres incline upwards, forming a series of curves with the 

 concavity turned upwards. The fibres of the palato-glossus muscle are found 

 by Zaglas and Henle to be continuous with fibres of the transverse set. 



Fig. 569. TRANSVERSE Fig. 569. 



VERTICAL SECTION OF THE 

 TONGUE IN FRONT OF THE 

 PAPILLA VALLAT.E, SEEN 



FROM BEFORE (from 



Kolliker). 



g, the genio-hyo-glossi 

 muscles ; </, the vertical 

 fibres of the right side traced 

 upwards to the surface ; li t 

 inferior longitudinal muscle 

 with the divided ranine ar- 

 tery ; tr, transverse muscle, 

 entire on one side, but par- 

 tially removed on the other, 

 where the other muscles pass 

 through it; c, septum lin- 

 guae ; h, hyo-glossus ; h g I, 

 its fibres spreading upwards 

 almost vertically outside the 

 genio-hyo-glossus ; k', vertical fibres reaching the surface ; Is, divided plates of the fibres 

 of the superior longitudinal muscle between the vertical fibres ; s t, g I, stylo-glossus ; d, 

 glands near the border of the tongue. 



Vertical fibres (musculus perpendicularis externus of Zaglas), decussating 

 with the transverse fibres and the insertions of the genio-glossus, form a set 

 of curves in each half of the tongue with their concavity upwards, and ex- 

 tending downwards and outwards from the dorsum to the under surface of 

 the border, so that those which are outermost are shortest. (Zaglas, " On 

 the Muscular Structure of the Tongue," in Goodsir's Annals, I. p. 1.) 



Examined in transverse sections, the muscular fibres of the tongue are seen 

 to be arranged so as to render the substance divisible into an outer part or 

 cortex and a softer internal medulla. The fibres of the cortex are principally 

 longitudinal, derived superiorly from the lingualis superior, further outwards 

 from the hyo-glossus, on the side from the stylo-glossus, and beneath this 

 from the lingualis inferior. They sheath the medullary part on all sides 

 except inferiorly, where the genio-glossi muscles enter it between the infe- 

 rior linguales. In the medullary part are found, imbedded in fat, the de- 

 cussating fibres of the transverse muscle passing across, the genio-glossi 

 radiating upwards and outwards, and the vertical muscles arching down- 

 wards and outwards. In addition to the movements which may be given 

 to the tongue -by the extrinsic muscles, this organ is capable of being curved 

 upwards, downwards, or laterally by its cortical fibres, it is flattened by the 

 vertical fibres, and its margins are again drawn together by the transverse. 



The septum of the tongue is a thin fibrous partition which extends forwards 

 from the hyoid bone to the tip, and divides one half of the medullary part of 

 the tongue from the other, but does not penetrate into the cortex. It cor- 

 responds with the fusiform fibro-cartilage, found in the middle of the tongue 

 of the dog, near its under surface. 



