34 



bulletin: museum of comparative zoology. 



2. Muscles of the Tongue. 



The tongue musculature consists of a set of longitudinal muscles 

 and an interlacing system of intrinsic fibers inserted on its mucous 

 membrane perpendicularly to the surface. The longitudinal muscles 

 consist of m. genioglossus {gen-gls.) and some others, to which specific 

 names will not be given. The genioglossus muscle is a paired structure 

 having its origin along a considerable extent of the cerato-branchial I. 

 (Plates 5-7, figs. 13-22; Fig. E). These bands passing forward form 

 rounded bundles extending the full length of the tongue and are more 

 or less surrounded by the other tongue muscles. Ventrally, however, 



sphlcoll. 



, omo-hy.prf. 



.Tirnd. 



ker-md i 



'dep.md. 



myl-hy. 



Fig. E. — Ventral aspect of head and neck after complete removal of the 

 mm. mylo-hyoideus, sphincter colli, cerato-mandibularis 1 and 2, and 

 omo-hyoideus (superflcialis). The m. omo-hyoideus profundus and the 

 m. cerato-mandibularis 1 of the left side remain to show more clearly their 

 position and e.xtent. The origin of m. cerato-mandibularis 2. indicated 

 by dotted lines, covers that of a part of the longitudinal tongue muscle. 



they are bounded by large lymph sinuses, which leave the tongue 

 attached by only its lateral muscular walls and thus permit its free 

 movement and change of form (Plate 4, figs. 9-11). 



Two other longitudinal muscles may be recognized. These are not 

 separable in their origin, but differ in their anterior attachment. 

 They arise on the ventral face of the genioglossus (Fig. E) at about 

 the level of the lar\Tix, and the bundles are increased by fibers springing 

 apparently from the connective tissue underlying the mucous mem- 

 brane lateral to this muscle (Plate 5, fig. 12, Ing. Ig.) Passing forward 

 this divides into two liundles with different relations to the tongue. 



