392 DIGESTIVE SYSTEM OF THE HORSE 
The latter are marked by crypts and consist essentially of a mass of lymphoid 
tissue; they are known as lingual follicles (Folliculi linguales), and taken together 
form what is sometimes called the lingual tonsil. The lingual glands (Glandule 
linguales) constitute a thick layer in the loose submucous tissue and also lie between 
the muscle bundles. Mucous glands are found also in part of the dorsum and sides 
of the tongue. 
The lingual muscles (Mm. lingue) may be divided into intrinsic and extrinsic. 
The intrinsic musculature consists, not of distinct muscles, but rather of systems 
of fibers which run longitudinally, vertically, and transversely, blending with the 
extrinsic muscles, which are now to be deseribed.! 
Kerato-hyoideus — Hyo-pharyngeus 
Genio-glossus Thyroid Trachea 
Depressor labii gland 
infertoris 
TI'ig. 332.—Musc.ies or Toneve, Hrorn Bone, PHarynx, Evc., OF Horse. 
— 
T. p., Tensor palati; L. p., levator palati; Pt. p., pterygo-pharyngeus; P. p., palato-pharyngeus; SS. p., stylo- 
pharyngeus; Th. p., thyro-pharyngeus; C. p., crico-pharyngeus; Th. h., thyro-hyoideus; Hyo. gl., hyo-glossus; G. py 
guttural pouch; F. p., foliate papilla; A. »., facial artery and vein. Most of the left ramus of the mandible is removed, 
The concealed parts of the hyoid bone are indicated by dotted lines. 
1. Stylo-glossus.—This is a long, thin muscle, which lies along the lateral part 
of the tongue. It arises by a thin tendon from the lateral surface of the great 
cornu of the hyoid bone, near the articulation with the small cornu. It terminates 
near the tip of the tongue by blending with its fellow of the opposite side and with 
the intrinsic musculature. The action is to retract the tongue. Unilateral con- 
traction would also draw the tongue toward the side of the muscle acting. 
A small muscular band sometimes arises on the thyroid cornu of the hyoid bone and ends 
on the tendon of origin of the stylo-glossus. In some eases a similar band arises higher up, with 
and on the hyo-glossus. 
2. Hyo-glossus.—This is a wide, flat muscle, somewhat thicker than the pre- 
1 This distinction is more or less conventional. It is evident that much of what may appear 
on cross-sections of the tongue to be intrinsic muscle is in reality a part of the extrinsic musculature. 
The arrangement is further complicated by the existence of bundles running in various directions, 
intercrossing of bundles, and the breaking up of the systems by masses of fat. 
