TONGUE. 



1141 



first described by Nuck, may generally be de- 

 tected : they are about eight or ten in num- 

 ber, much smaller than those at the base, 

 situated on each side of the median furrow, 

 and each surmounted by a little orifice. The 

 true glandular nature of all these structures 

 is proved by microscopical examination : they 

 are seen to be true conglomerate glands, their 

 ultimate follicles filled with an abundant se- 

 creting epithelium. 



Vessels of the tongue. The vascular supply 

 of this organ, which is large in proportion to 

 its size, is derived mainly from its proper ar- 

 tery, the lingual, but it receives some small 

 branches at its sides and base from the inferior 

 pharyngeal and palatine. The lingual artery 

 arises from the external carotid, between the 

 inferior thyroid and the facial : it passes up- 

 wards and inwards, at first superficial, covered 

 only by the integument and fasciae, to reach 

 the posterior border of the hyoglossus muscle, 

 beneath which it passes to its anterior border, 

 where it breaks up into its terminal branches, 

 the sublingual and the ran'me. In the first part 

 of its course it lies on the middle constrictor of 

 the pharynx ; in the second part it is covered 

 by the hyoglossus and mylohyoid muscles, 

 and lies on the middle constrictor and genio- 

 glossus. Previous to passing beneath the 

 posterior border of the hyoglossus the artery 

 is crossed by the hypoglossal nerve, which, at 

 first placed below it, now rises above it ; the 

 hyoglossus muscle then separates the two, 

 the nerve lying outside of it and the artery 

 beneath it, but at its anterior border they are 

 again in relation ; the nerve, however, is now 

 inferior, having crossed the course of the 

 artery while beneath the hyoglossus. Its 

 branches are, 1st, a hyoid branch, passing along 

 the upper margin of the hyoid bone, corre- 

 sponding to a branch of the superior thyroid 

 running along the under margin of the bone, 

 with which and with its fellow of the opposite 

 side it anastomoses ; 2dly, the dorsalis linguce 

 branch, ascending from the artery in the se- 

 cond part of its course, supplying the side and 

 dorsum of the tongue ; 3dly, the sublingual, 

 one of its two terminal branches, passing 

 downwards and outwards from the anterior 

 margin of the hyoglossus to be distributed to 

 the sublingual gland, cellular tissue, and mu- 

 cous membrane adjacent ; 4thly, the ranine, 

 which may be regarded as its continuation, 

 passing upwards and inwards in immediate 

 relation with the genioglossus to the tip, 

 where it anastomoses with its fellow. That 

 the communication of the arteries of the 

 opposite sides of the tongue is not very free, 

 is shown by the imperfect injection of one side 

 when the injection is made into the carotid of 

 the opposite side : it is free enough, however, 

 to make the ligature of the artery of one side 

 of little service in stopping haemorrhage of 

 that side, the supply from the other being 

 sufficient to keep it up. 



Nerves of the tongue. The tongue is sup- 

 plied with nerves from three sources, two 

 sentient the lingual branch of the fifth, and 

 the glosso-pharyngeal y and one motor the 



ninth or hypoglossal nerve. The lingual or gus- 

 tatory nerve, one of the three great branches 

 into which the sensory portion of the inferior 

 maxillary division of the fifth breaks up after 

 its emergence through the foramen ovale, 

 passes down, at first between the external 

 pterygoid muscle and the small muscles of the 

 palate, then between the two pterygoids, then 

 between the internal pterygoids and the jaw, 

 finally escaping from between these two at 

 the anterior border of the muscle ; it then 

 runs downwards and forwards, under the pro- 

 tection of the jaw, to the side of the tongue, 

 crosses the mylohyoid attachment of the 

 superior constrictor, then passes forwards 

 beneath the sublingual gland and to the outer 

 side of the ranine artery, to terminate at 

 the tip of the tongue. The numerous small 

 branches that are distributed to the conical 

 and fungiform papillae may be seen ascending 

 from the nerve whilst beneath the tongue, 

 passing upwards and forwards through the 

 substance of the organ to the mucous surface. 

 The other nerve of sensation, the glosso-pha- 

 ryngeal, the smallest and most anterior di- 

 vision of the eighth pair, emerges from the 

 skull through the foramen lacerum jugulare 

 by a distinct fibrous canal ; it then descends 

 between the jugular vein and internal carotid, 

 passing forwards, in front of that artery and 

 beneath the styloid process and muscles aris- 

 ing from it, to the anterior border of the stylo- 

 pharyngeus, between that muscle and the 

 styloglossus ; it then passes under the hyo- 

 glossus, beneath which and below the tonsil 

 it divides into its branches for the supply of 

 the gland and the tongue : its arch across the 

 neck is below that^ of the lingual, and above 

 the hypoglossal, but deeper seated than either. 

 The branches to the tongue are distributed 

 to the circumvallate papillae, and the mucous 

 surface behind them. The ninth, or hypo- 

 glossal nerve, the motor nerve of the tongue, 

 after escaping from the skull through the an- 

 terior condyloid foramen, lies at first deep, 

 between the internal jugular vein and carotid 

 artery ; coming forward between them it be- 

 comes superficial, and forms an arch across 

 the neck below, and parallel to, the digastric 

 muscle, hooks round the occipital artery, and 

 passes beneath the mylohyoid muscle, but 

 superficial to the hyoglossus, at the anterior 

 border of which it pierces the fibres of the 

 genioglossus, and divides into its branches 

 jfor the supply of this and the other muscles 

 of the tongue : its relations to the lingual 

 artery have been mentioned. For a more 

 detailed account of these nerves, of their 

 relations, branches, and the experiments on 

 the results of which the present amount of 

 our knowledge as to their function is based, 

 the reader is referred to the articles FIFTH 

 NERVE, EIGHTH NERVE, NINTH NERVE, and 

 TASTE. 



COMPARATIVE ANATOMY. The first in- 

 dication that we find of any thing that can 

 be construed into a tongue is met with in 

 the Articulata, and, among them, in Insects. 

 Its claim to the name is a matter of doubt 

 4 D 3 



