THE SALIVARY GLANDS. 369 



Excretory Canal Wharton's 'duct, as it is termed, is long and narrow ; 

 has very attenuated, walls, and exists for nearly the whole length of the 

 superior border of the gland : sometimes on its internal face, where it receives 

 the ramifications from various lobules. At the anterior extremity of the 

 organ it becomes free, and passes forward between the mylo-hyoideus and 

 basio- (hyo-) glossus muscles. After crossing outwardly, the glosso-facial 

 artery and great hypoglossal nerve, and, inwardly, the tendon of the digas- 

 tricus and the lingual nerve, it passes between the hyo-glossus longus and 

 the sublingual gland, lying closely to the inner side of the latter ; thus it 

 extends parallel to the lateral groove (or channel) of the lingual canal (on 

 the floor of the mouth). It finally arrives near the fraenum of the tongue, 

 but underneath the buccal membrane, and opens into the mouth by a small, 

 but very salient, floating tubercle, situated a little in advance of the freenum, 

 and vulgarly named the barb (barbillon). 



The structure of Wharton's duct is identical with that of Stenon, but its 

 external tunic is extremely thin, and has not any circular elastic fibres. 



3. Sublingual Gland. (Fig. 173.) 



This is less in volume than the preceding, and is situated under the 

 tongue, in the intermaxillary space. 



Elongated from before to behind, and very flat laterally, it has, like 

 the submaxillary gland, two faces, two borders, and two extremities, whose 

 relations we will briefly indicate. 



The external face is covered by the mylo-hyoideus muscle ; the internal 

 responds to Wharton's duct and the genio-glossus and hyo-glossus langus 

 muscles. The upper border projects beneath the mucous membrane on the 

 floor of the mouth, where it forms the sublingual ridge ; the inferior, thin 

 and sharp, is comprised between the mylo-hyoideus and the genio-glossus 

 muscles. The two extremities are thin and tapering ; the posterior contains 

 a branch of the lingual nerve ; the anterior extends to the bottom of the 

 angle formed by the union of the two branches of the inferior maxilla. 



Vessels and nerves. This gland possesses a special, but small artery the 

 sublingual Its nerves come from the lingual nerve, and even from the 

 carotid plexus. 



Excretory canals. These number fifteen or twenty, and are named the 

 ductus Biviniani. Flexuous and very slender, they are detached from the 

 superior border or internal face of the gland, ascend perpendicularly, and 

 open into the mouth on the sublingual crest or ridge by a linear series 

 of small orifices pierced, as usual, in the centre of a tubercle. 



4. Molar Glands. 



These are so named because they are disposed parallel to the molar arches. 

 There are two on each side. 



The superior molar gland, the most considerable, represents a narrow 

 line of salivary lobules placed outside, and along the upper border of, the 

 alveolo-labialis muscle. In its posterior part, where it is concealed beneath 

 the masseter muscle, this gland is thicker and more compact than in front, 

 where the few lobules which compose it scarcely come in contact with each 

 other. 



The inferior molar gland, less lobulated and voluminous, and not so 

 wide as the preceding, is placed at the inferior border of the buccinator, 

 immediately beneath the mucous membrane of the mouth, and near the 



