286 ELEMENTARY ANATOMY. [LESS. 



of the orbit it passes through a fibro-cartilaginous ring or 

 pulley, which changes the direction of the tendon, as, after 

 traversing it, the tendon returns backwards to be inserted 

 between the upper and external recti muscles. 



The obliquus inferior has no pulley, and is the only short 

 muscle in the orbit. It springs from the orbital plate of the 

 maxilla near the lachrymal groove, and, passing backwards 

 between the floor of the orbit and the globe of the eye, is 

 inserted into the postero-external aspect of the latter. 



The platysma myoides is a thin muscle placed imme- 

 diately beneath the skin of the neck, and extending from the 

 mandible downwards to the chest and shoulders. 



The sterno-cleido mastoid is a long stout muscular strap, 

 double at its lower end and arising partly from the clavicle 

 and partly from the sternum, and inserted into the mastoid 

 process. 



The digastric is a muscle with two fleshy bellies, with a 

 median tendon. Arising from the mastoid, it is inserted 

 inside the mandible close to the symphysis. The median 

 tendon is connected with the os hyoides. 



FIG. 264. MUSCLES OF THE RIGHT SIDE OF THE TONGUE. 



i, stylo-glossus ; 2, stylo-hyoicl ; 3, stylo-pharyngeus ; 4, hyo-glossus ; 5, genio- 

 hyoid ; 6, genio-glossus ; 7, lingualis. 



The stylo-hyoid, stylo-glossus, and stylo-pharyngeus are three 

 slender muscles all springing from the styloid process, and 

 inserted, the first into the corniculum of the hyoid, the second 

 into the base of the tongue, and the third into the thyroid 

 cartilage of the larynx. 1 



The mylo-hyoidis a flat muscle, and passes from inside the 

 mandible to the body of the hyoid. It unites with its fellow 



1 For a description of the larynx see Lesson XII. 



