THE TONGUE. 313 



raphe, which is a vertical septum of ligamentous matter, 

 making the tongue consist of two equal and symmetrical 

 parts. 



The anterior third of the tongue is the only portion free 

 on its lower surface, all the rest being attached by mus- 

 cles. On this surface is noticed, along its middle, a furrow 

 from the posterior part of which a fold of mucous mem- 

 brane passes to the posterior surface of the symphysis 

 menti. This fold is called the frenum linguce, and is the 

 part concerned in the "tongue-tie" of children, where it is 

 too short and requires division. The ranine veins are 

 plainly seen on each side of this furrow. 



Muscles of the Tongue. The muscles of the tongue (Fig. 

 87) consist of four pair, which have been given at the 

 beginning of this section, except one, the lingualis. This 

 is the intrinsic muscle of the tongue, and consists of a 

 slender fasciculus of fibres, arising indistinctly among the 

 yellow cellular tissue at its base, and passing forward 

 between the hyo-glossus and genio Jiyo-glossus, to the tip. 

 Its fibres run in different directions being transverse and 

 vertical, as well as longitudinal ; hence the terms transverse 

 lingual, and vertical lingual muscles. 



The superficial fibres of this muscle are closely connected 

 with the dense papillary membrane or corium, which is a 

 kind of skeleton upon which they, with the other fibres, 

 act in effecting changes both in the form and density of the 

 tongue. Thus, by means of this extensive muscular appara- 

 tus, the tongue has the power of moving in every possible 

 direction of keeping the food beneath the teeth, and of 

 passing it from the mouth into the pharynx thereby per- 

 forming a most efficient part in mastication, as well as 

 deglutition. 



Blood-vessels of the Tongue 9 (Figs. T3, 91.) The arteries 

 come principally from the lingual, a branch of the external 

 carotid, and injections seem to show that the arteries be- 

 longing to either half of the tongue advance to its vertical 

 septum, and then stop those of the one side having no 

 anastomosis with those of the other, being effectually pre- 



