956 THE DIGESTIVE SYSTEM. 
hyoglossal membrane) which is united to the upper border of the hyoid bone, and gives 
attachment to the posterior fibres of the genioglossus. From the sides of the septum the 
transverse fibres of the tongue arise. 
The mucous membrane on the anterior two-thirds of the dorsum, and on the free 
margins, is firm and closely adherent to the underlying muscular substance, the fibres 
of which are inserted into it. On the posterior third of the dorsum, and on the inferior 
surface, it is neither so firm nor so closely united to the muscular substance, from which 
it is separated in both of these situations by a layer of submucous tissue. 
The mucous membrane of the tongue, like that of the rest of the mouth, is covered 
by stratified squamous epithelium. 
Glands of the Tongue—Numerous small racemose glands are found scattered beneath the 
mucous membrane of the posterior third of the tongue ; and a small collection of similar glands 
is present at the margin, opposite the circumvallate papille. Small serous glands are also 
found embedded in the dorsum near the ecireumvallate papille, into the fossee of which their 
ducts open (Fig. 642). 
The chief collections of glandular tissue in the tongue, however, are found embedded in the 
muscle of the under surface, a little way behind the apex, on each side of the middle line (Fig. 
643). They are known as the apical glands (glandulie linguales anteriores of Nuhn or Blandin). 
These apical glands are displayed by removing the mucous membrane and also a layer of 
| 
Superior Vertical Nodules of 
lingualis fibres Epithelium lymphoid tissue 
SURES VON 
Transverse Vertical 
fibres fibres 
OVS WY 
aes 2 pas M/W off ' 
4s ai ee fe ave Ale: WE ii if a8 7 
me fh fe Ny Die A ie i 
Sh SSIIF; Y ez Fl . 
Tr — 
| 
Sur 
Transverse fibres 
B C 
Inferior lingualis 
Septum 
Fat 
Fic. 644.—A, TRANSVERSE, AND B, LONGITUDINAL VERTICAL SECTION THROUGH THE TONGUE (Krause) ; 
C, A LympHorp FouuicLE FROM Back Part oF ToNGUE (Macalister, slightly modified). 
muscular fibres (derived from the united inferior lingualis and styloglossus) about 2 mm. in 
thickness from the under surface of the tongue a little distance behind the apex. They are oval in 
shape, often partly broken up by muscular fibres, and they measure from $ to # in. (12 to 19 mm.) 
in length. 'They are mixed serous and mucous glands, and they open by three or four very 
small ducts on the inferior surface of the tongue. 
Vessels.—The chief artery is the lingual. This vessel passes forwards on each side beneath 
the hyoglossus muscle, and then is continued on to the apex-—between the genioglossus on the 
inner side and the inferior lingualis externally—under the name of the ranine artery. Anteriorly 
it is covered by the fibres of the inferior lingualis, and lies } to ¢ inch from the surface. Near 
the apex the arteries of opposite sides are connected by a branch which pierces the septum, but 
otherwise, with the exception of capillary anastomosis, they do not communicate. The dorsalis 
lingue branch of the lingual is distributed to the pharyngeal part of the tongue, whilst some 
twigs of the tonsillar branch of the facial are also distributed in the same region. 
'The veins are: the ranine, the chief vein, which lies beneath the mucous membrane at the 
side of the frenum, and runs backwards over the hyoglossus muscle with the hypoglossal nerve ; 
two vene comites, which accompany the lingual artery ; and a dorsalis lingue vein from the back 
of the tongue. These either unite and form a common trunk, or open separately into the internal 
jugular vein. 
Nerves.—The nerves which supply the tongue are: (1) The hypoglossal, the motor nerve of 
the tongue, which enters the genioglossus and passes up in its substance to the intrinsic muscles, 
in which it ends. (2) The lingual, a branch of the inferior maxillary nerve, which is accom- 
panied by the chorda tympani branch of the facial. The lingual, after crossing the hyoglossus 
muscle, breaks up and enters the inferior lingualis and gemioglossus, and thus makes its way 
upwards to the mucous membrane of the anterior two-thirds of the tongue—the lingual itself 
conferring common sensation on this part, the chorda tympani probably carrying to it taste 
