GUSTATORY NERVE. 101 



act from the jaw : Thus the fibres attached to the os hyoides advance 

 and fix that bone before swallowing ; the hinder tongue fibres raise the 

 root of the tongue and protrude the tip, and the anterior then turn down 

 the tip of the tongue over the teeth. 



AVhen the mouth is open swallowing can be performed if the tongue is 

 fixed against the teeth and roof of the mouth, because this muscle and the 

 hyo-glossus can then raise the hyoid bone. 



The lingual artery (fig. 17,/), arises from the external carotid between 

 the superior thyroid and facial branches. At first it is directed inwards 

 above the os hyoides, and then upwards beneath the hyo-glossus to the 

 under part of the tongue (fig. 23) ; it ends at the anterior border of that 

 muscle in the sublingual and ranine branches. Near the hyo-glossus the 

 artery is crossed by the ninth nerve, and by the digastric and stylo-hyoid 

 muscles. Beneath the hyo-glossus, the vessel rests on the middle con- 

 strictor and genio-hyo-glossus muscles, and is below the level of the glosso- 

 pharyngeal nerve. Its branches are these : 



a. A small hyoid branch is distributed on the upper border of the os 

 hyoides, supplying the muscles ; it anastomoses with its fellow of the oppo- 

 site side, and with the hyoid branch of the superior thyroid artery of the 

 same side. 



b. A branch to the dorsum of the tongue arises beneath the hyo-glossus 

 muscle, and ascends to supply the substance of the tongue and the tonsil. 

 The fibres of the hyo-glossus must be divided to see it. 



6'. The siiblingiial branch springs from the final division of the artery 

 at the edge of the hyo-glossus, and is directed outwards to the gland of the 

 same name. Some offsets supply the gums and the contiguous muscles, 

 and one continues behind the incisor teeth to join a similar artery from 

 the other side. 



d. The ranine branch (9) is the terminal part of the lingual artery, and 

 extends forwards along the outer side of the genio-hyo-glossus to the tip 

 of the tongue where it ends. Muscular offsets are furnished to the sub- 

 stance of the tongue of the same side. This artery lies along the frasnum 

 linguae, but is imbedded in the muscular fibres. 



The lingual vein commences on both the upper and under surfaces of 

 the tongue. It lies with its companion artery, and ends in the internal 

 jugular vein. 



The GUSTATORY or LINGUAL NERVE (fig. 23, *) has been followed in 

 the pterygo-maxillary region to its passage between the rarnus of the 

 lower jaw and the internal pterygoid muscle (p. 97). In this dissection 

 the nerve is inclined forwards to the side of the tongue, across the mucous 

 membrane of the mouth and the origin of the superior constrictor muscle, 

 and above the deep part of the submaxillary gland. Lastly, it is directed 

 across the Whartonian duct, and along the side of the tongue to the apex. 

 Branches are furnished to the surrounding parts, thus : 



Two or more offsets connect it with the submaxillary ganglion, near the 

 gland of that name. 



Farther forwards branches descend on the hyo-glossus to unite in a kind 

 of plexus with twigs of the hypoglossal nerve. 



Other filaments are supplied to the mucous membrane of the mouth, the 

 gums, and the sublingual gland. 



Lastly, the branches for the tongue ascend through the muscular sub- 

 stance, and are distributed to the conical and fungiform papilla 1 . 



The submaxillary ganglion (fig. 23, 2 ) resembles the other ganglia 



