THE MOUTH. 



403 



only exist at the base of the tongue, where two of their number, very developed 

 and composite, correspond to the blind foramina of Morgagm (foramen ctecum). 

 At the base of a certain number of the fungiform and calyciform papillae is a 

 band of adenoid tissue. 



It is generally beheved that these three kinds of papillae have each a distinct 

 function ; the filiform are to retain the alimentary and sapid substances on the 

 surface of the tongue, the fungiform are tactile organs, and the calyciform are 

 gustatory. 



2. Muscles. — Beneath the mucous membrane, on the dorsal surface of the 

 tongue, is a cylindrical fibrous cord, which sometimes attains the thickness of a 

 large goose-quill. This cord is situated in the median plane, near the middle 

 part of the organ, and is from 2 to 3 inches long. It may be considered as a 

 fibrous support to the muscular tissue, and it sometimes directly adheres to the 

 deep surface of the mucous membrane. At other times, it is only connected 



Fig. 218. 



FORAMEN OF MORGAGNI IN 

 THE horse's tongue (SEEN 

 FROM above). 



VERTICAL section OF A FORAMEN C^CUM OF THE 

 horse's TONGUE. 



1, 1, Borders of the calyx ; 2, fungiform papillsc occupying 

 it ; 3, section of the ring of lymphoid tissue ; 4, racemose 

 glands ; 5, muscular fibres of the tongue. 



with that membrane by a very short lamellar prolongation, and is then buried a 

 little deeper among the fibres of the superior muscular layer. 



(The German hippotomists designate this the cartilage of the tongue. It is 

 only found in Solipeds, and was first described by Briihl, who gave it this desig- 

 nation. Leyh states that it is composed of dense fibro-cartilage, surrounded by 

 connective and adipose tissue ; that it is from 4 to 7 inches long, and f to 1 inch 

 in thickness ; and that it commences about an inch from the anterior appendix 

 of the hyoid bone.) 



A similar cord, but not so strong or well-defined, is sometimes found at the 

 inferior surface of the free portion of the tongue. 



Intrinsic muscles. — In studying the proper substance of the tongue in two 

 sections — one vertical and longitudinal, the other transverse — there is seen, 

 under the dorsal mucous membrane, a layer of red fibres, close in their texture, 

 and very adherent to that membrane. Amongst these fibres, there are some 

 which aifect a longitudinal direction, but the majority are vertical or transverse, 

 and all are interlaced in the most intimate manner. It appears as if this layer 

 (the lingualis superficialis of Man) were perfectly independent of the other 

 muscular fibres, the insertion of which it receives. It also forms a portion of 

 those which writers have named the intrinsic muscles of the tongue, and which 



