SPECIAL ANATOMY. 133 



and muscular structures become intimately blended with 

 the deep surface of the mucous membrane, thus constituting 

 a somewhat firm layer into which some of the more definite 

 muscles are inserted. The mucous membrane of the lateral 

 part of the tongue presents several small papillae on which 

 the ducts of the sublingual salivary glands open. These may 

 be seen as thin white threads running from the glands, on 

 elevation of the mucous membrane. Superiorly to these 

 we see somewhat large fungiform papillse, so named from 

 their resemblance to a mushroom in shape. These are 

 found only on the lateral parts of the tongue, and on their 

 surface present filiform papillae, larger specimens of which 

 may be found on the major part of the dorstim or upper 

 surface of the tongue to which they communicate the pecu- 

 liar velvety feel. They are hair-like prolongations of the 

 mucous membrane, and are either simple or compound. The 

 anterior part of the dorsum of the tongue presents a 

 central' fissure, the result of the frequent longitudinal 

 folding of this portion of the organ. The anterior edge of 

 this part is rounded and the inferior surface along the 

 central line presents the attachment of the fraenum. The 

 posterior part of the dorsum surface of the tongue, elevated 

 above the anterior part, presents two remarkable round 

 spots which, on examination, prove to be collections of 

 fungiform papillae surrounded by a deep groove (circum- 

 vallate papillae). These are situated centrally about an 

 inch from each other. A smaller one may be sometimes 

 seen just behind them. 



We must now examine the hyoid bone or bone of the 

 tongue. This forms the basis of attachment of the pha- 

 rynx, larynx, and other structures situated in this neigh- 

 bourhood. It is suspended from the under surface of 

 the cranium, and hangs between the rami of the in- 

 ferior maxilla. It consists of five distinct portions : a 

 main portion and four cornua. The main portion closely 

 resembles a hunting spur, being composed of a spur 

 process, running in an anterior direction, and two heel 

 processes, which diverge from each other and run backwards 

 about three inches, " forming a crescentic space between 

 them." These two processes terminate posteriorly each in 

 a point which is continuous with the free extremity of the 

 cornu of the thyroid cartilage. They present a superior 

 sharpened margin for muscular attachment, and an inferior 



