MUSCULAR SYSTEM. 99 



Slniclnre. — Thin, weak, aponeurotic, at its posterior attach- 

 ment : remainder, fleshy. 



Action. — To draw the tongue within the mouth ; and at tiie 

 same time, depress it. 



HYO-GLOSSUS B RE VIS. HyO-gloSSUS. 



Situation. — Similar to the preceding- muscle. 



Form. — Broad, flat, thin, quadrilateral, half-penniforni. 



Attachment. — Externally, to the side of the body of" the 

 OS hyoides ; internally, to the base of the tongue. 



Relations. — Externally, with the mylo-hyoideus and hyo- 

 glossus longus; internally, with the genio-hyo-glossus. 



Direction. — Obliquely transverse. 



Structure. — Entirely fleshy. 



Action. — To assist the former muscle in the retraction of the 

 tongue ; and to depress, in particular, the base of it. 



GENIO-HYO-GLOSSUS. — Gcuio-gloSSUS. 



Situation. — Inferior part of the tongue. 



Form. — Broad, thin, half-penniform. 



Attachment. — Inferiorly, to the inner part of the jaw, near its 

 symphysis: superiorly, to the under part of the tongue; and also 

 to the appendix of the os hyoides. 



Relations. — Externally, with the genio-hyoideus, hyo glossus, 

 sublingual gland, and branches of the gustatory nerve ; internally, 

 with its fellow ; inferiorly, with the genio-hyoideus ; superiorly, 

 with the tongue. 



Direction. — From below, upwards; and from before, back- 

 wards. 



Structure. — Fleshy ; with the exception of the anterior half of 

 its inferior border, where it is hemmed by a slender tendon which 

 connects it more firmly to the jaw. Its surfaces are in part covered 

 with adipose substance. 



Action. — To project the tongue within the mouth, and draw it 

 down : if one muscle act alone, the organ will be drawn to one 

 side. 



LINGUALIS. 



The internal substance of the tongue consists of masses of 

 fleshy fibres, taking various directions, and having interwoven 

 with them a considerable quantity of yellow adipose tissue : 

 anatomists consider these as a distinct pair of muscles. They 

 take their attachments at the root of the tongue, from the body and 

 appendices of the os hyoides, where they are separable and dis- 

 tinct portions ; and proceed downwards, between the hyo-glossi 

 longi, and above the gcnio-hyo-glossi, to be buried and con- 



