THE PALATE. 333 



with their concavity outwards, and extending down and out 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 are seen to 

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

 part or coiiex and an internal or central part. The fibres of the cortex 

 are principally longitudinal, derived superiorly from the lingualis supe- 

 rior, further outwards from the hyo-glossus, on the side from the stylo- 

 glossus, and beneath this from the lingualis inferior. They ensheath 

 the medullary part on all sides except inferiorly, where the genio-glossi 

 muscles enter it between the inferior linguales. In the medullary part 

 are found, imbedded in fat, the decussating fibres of the transverse 

 muscle passing across, the genio-glossi radiating upwards and outwards, 

 and the vertical muscles arching downwards 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 : whilst the 

 two last mentioned, acting together, would tend to lengthen the organ. 



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 fi'om the other, but does not penetrate 

 into the cortex. 



The arteries of the tongue are derived from the lingTialis, with some small 

 branches from the facial and ascending i^haryngeal. With these the veins for 

 the most part correspond. 



The nerves of the tongue (exclusive of Ijranches from the sympathetic nerves) 

 are three ; viz.. thelingnal or g-ustatory branch of the fifth pair, which supplies 

 the papillas and mucous memJjrane of tlie fore part and sides of the tongue to 

 the extent of about two-thirds of its surface ; the lingiial branch of the g-losso- 

 pharyngeal, which sends filaments to the mucous membrane at the l:)ase of the 

 tongue, and especially to the papillaj vaUatai ; and, lastly, the hypoglossal nerve, 

 which is distributed to the muscles. Microscopic ganglia exist upon the expan- 

 sion of the glosso-pharj^igeal nerve, and in the sheep and calf upon the gustatory 

 division of the fifth. 



The detailed description of the l)lood- vessels and nerves wiU be found else- 

 where. 



THE PALATE. 



The roof of the mouth is formed by the palate, which consists of two 

 portions ; the fore part being named the hard palate, and the back part, 

 the soft palate. 



The osseous framework of the hard palate, already described with 

 the bones of the face, is covered by the periosteum, and by the lining 

 membrane of the mouthy Avhich adhere intimately together. The 

 mucous membrane, which is continuous with that of the gums, is thick, 

 dense, rather pale, and much corrugated, especially in front and at the 

 sides ; but is smoother, thinner, and of a deeper colour behind. Along 

 the middle line is a ridge or raphe, ending in front in a small eminence, 

 which corresponds with the lower opening of the anterior palatine canal, 

 and receives the terminal filaments of the naso-palatine and anterior 

 palatine nerves. The membrane of the hard palate is provided with 

 many muciparous glands, which form a continuous layer between th*^ 



