INFERIOR EXTREMITY OF THE HEAD. 75 



4. The Lingual Canal (Figs. 25 and 26). 



Situation ; Limits ; Anatomical Base. The lingual canal 

 is generally described as the space comprised between the branches of 

 the inferior maxilla, in which the tongue is situated. It is a kind of 

 gutter the sides of which are covered by the mucous membrane of the 

 mouth. Anteriorly, where its inferior wall is formed by the body of 

 the aforesaid bone, it is single ; posteriorly, it divides into two branches 

 comprised between the sides of the rami of the same bone and side of 

 the fixed portion of the tongue. 



At the anterior extremity of these lateral divisions is the lingual crest formed 

 by the superior border of the sublingual gland, covered by mucous membrane, 

 and presenting a series of orifices of the excretory ducts, ducti Riviniani. 



Underneath the mucous membrane covering the lateral faces of the tongue 

 is the duct of Wharton, the excretory canal of the maxillary salivary gland. It 

 opens upon the superior face of the body of the maxilla on each side of the 

 frasnum of the tongue by means of an enlargement called the barb or barbillon, 

 whose function is the protection of the canal against the entrance of alimentary 

 matters. 



Depth. The lingual canal, which we must examine in regard to 

 its depth, should be proportional to the volume of the tongue. If 

 the latter be not in relation with the capacity of the gutter which con- 

 tains it, the result will be a vicious position of the bit ; in the one 

 case the tongue will entirely support the action of the bit, whilst in the 

 other the latter will rest exclusively upon the bars. We must say, to 

 speak the truth, that nothing has been demonstrated to establish this 

 opinion. The width of the canal is always in relation with the volume 

 of the tongue, and, should it be otherwise, the bit will experience 

 neither more nor less difficulty, as we shall show further on. 



We think, also, that there is neither beauty nor defect to be appre- 

 ciated in this region. We may, however, observe an inflammation of 

 the canal of Wharton from the introduction, through the barbs, of 

 particles of forage proving very often to be pieces of brome-grass. 

 This affection is noticed most frequently in old horses with irregular 

 teeth, and nourished on old Burgundian hay, in which this grass 

 is abundant. It is accompanied by intense congestion of the barb, 

 and perhaps a discharge of pus from its orifice. 



It was formerly believed that the barbs could prevent the animal from drink- 

 ing. It is surprising that this opinion was even shared by Bourgelat, who con- 

 sidered these organs simply as excrescences of the mucous membrane. At 

 present, many persons in the rural districts are imbued with this prejudice, and 

 employ horsemen and empirics who practice its ablation. It is easily understood 



