THE TONGUE. 



815 



Crlands of the Tongue. The tongue is provided with mucous and serous 

 glands. 



The mucous glands are similar in structure to the labial and buccal glands. 

 They are found especially at the back part, behind the circumvallate papillae, 

 but are also present at the apex and marginal parts. In connection with these 

 glands a special one has been described by Blandin or Nuhn. It is situated near 

 the apex of the tongue on either side of the frsenum, and is covered over by a 



Bristles 

 in ducts 

 of glands. 



Lingual nerve. Ranine artery. 



FIG. 432. Under surface of tongue, showing position and relations of gland of Blandin or Nuhn. (From a 

 preparation in the Museum of the Royal College of Surgeons of England.) 



fasciculus of muscular fibre derived from the Stylo-glossus and Inferior lingualis. 

 It is from half an inch to nearly an inch long and about the third of an inch 

 broad. It has from four to six ducts, which open on the under surface of the 

 apex. 



The serous glands occur only at the back of the tongue in the neighborhood 

 of the taste-buds, their ducts opening for the most part into the fossae of the cir- 

 cumvallate papillae. These glands are racemose, the duct branching into several 

 minute ducts, which terminate in alveoli lined by a single layer of more or less 

 columnar epithelium. Their secretion is of a watery nature, and probably assists 

 in the distribution of the substance to be tasted over the taste-area (Ebner). 



The fibrous septum consists of a vertical layer of fibrous tissue, extending 

 throughout the entire length of the middle line of the tongue, from the base 

 to the apex, though not quite reaching the dorsum. It is thicker behind than 

 in front, and occasionally contains a small fibro-cartilage about a quarter of an 

 inch in length. It is well displayed by making a vertical section across the 

 organ. 



The Hyo-glossal membrane is a strong fibrous lamina which connects the under 

 surface of the base of the tongue to the body of the hyoid bone. This membrane 

 receives, in front, some of the fibres of the Genio-hyo-glossi. 



Vessels of the Tongue. The arteries of the tongue are derived from the lin- 

 gual, the facial, and ascending pharyngeal. The veins open into the internal 

 jugular. 



Muscles of the Tongue. The muscular fibres of the tongue run in various 

 directions. These fibres are divided into two sets, Extrinsic and Intrinsic, Avhich 

 have already been described (page 32f>). 



The lymphatic vessels from the tongue pass to one or two small glands situated 



