THE TONGrE 



By ARTHUR HENSMAN, F.R.C.S. 

 Revised for Second Edition by ARTHUR ROBINSOX, M.D., M.R.C.S. 



LECTURER ON ANATOMY IN THE MIDDLESEX HOSPITAL MEDICAL SCHOOL ; EXAMINER IN ANATOMY FOR THE 



CONJOINT BOARD OF ENGLAND 



The tongue is a freely inoval)le, highly sensitive, and muscular organ, and is 

 endowed witli the special sense of taste. It participates, moreover, in the 

 function of speech, and plays an important part in mastication and deglutition. 



Its upper surface, or dorsum, with its sides and tip, are free, whilst its Ijase is 

 attached by muscles to tlie hyoid bone and lower jaw. Folds of mucous membrane 

 loosely connect it with the epiglottis and soft palate, as well as Avith the symphysis 

 of the lower jaw. From beneath its rounded borders the mucous covering liecomes 

 continuous with the inner surface of tlie gums. The anterior two-thirds of the 

 tongue occupies the floor of the mouth, lying between the halves of the lower jaw, 

 with its convex dorsum overarched by the vault of the palate, and its sides and tip 

 in contact with the teeth and gums. The posterior third of the dorsum, situ- 

 ated in the anterior wall of the pharynx, forms a rounded surface overhanging the 

 epiglottis. 



The mucous membrane, which is really a modified skin, covers the whole of 

 the free surface of the tongue. It forms three folds: the glosso-epiglottidean in 

 connection with the epiglottis; and on each side of the median fold — fraenum 

 epiglottidis — is formed the glosso-epiglottidean pouch, or vallecula, which 

 is bounded externally hy the more rounded lateral fold. On each side of the 

 tongue, near the junction of the posterior and middle third, the membrane ascends 

 to form the anterior pillars of the fauces, and in front beneath the tip it forms 

 the sharp fold of the fraenum linguae (fig. 509), which extends forwards to the 

 back of the symphysis. 



A slight longitudinal groove, the median raphe, divides the dorsum of the 

 tongue along its anterior two-thirds. It ends posteriorly near a small foramen, 

 the foramen caecum, which represents the upper termination of the thyro-glossal 

 duct. The orifice, however, is not at all constant in the adult tongue, although 

 occasionally it is present and may sometimes lead into the still patent duct which 

 tunnels the tongue as far as the body of the hyoid bone. The course of the 

 obliterated duct may in many cases be demonstrated. 



The foramen ctecum is easily seen in the foetus at the angle of meeting of two 

 shallow grooves which form tlie V-shaped line liehind the circumvallate papilke. 

 These grooves indicate the line of junction of the anterior and posterior portions 

 of the tongue, and are faintly visible in the adult organ. 



The papilhe crowd the anterior two-tliirds of the dorsum as well as the sides 

 and tip of the tongue, l)ut at the back they are small and hidden ))y the epithelial 

 coating. Of the papilhe three chief kinds can be distinguished. 



The circumvallate or calyciform papillae are the largest, but they are few in 

 number, varying from seven or eight to twelve, and they form a V-shaped line in 

 front of and parallel witli the grooves already mentioned. 



884 



