9 2 ANATOMY AND PHYSIOLOGY 



They are the sterno-hyoid, the sterno- thyroid, and the omo-hyoid (a 



double-bellied muscle with an intervening tendon, the inferior belly being 

 attached to the upper border of the scapula, the superior belly to the hyoid 

 bone, while the tendon between them glides through a loop of fascia attached 

 to the clavicula). 



FIG. 78. MUSCLES IN FRONT or THE NECK. 



"i, 2, 3, Digastric muscle; 4, stylo-hyoid; 5, mylo-hyoid; 6, hyo-glossus; 7, 8, 9, 

 sterno-mastoid; 10, n, 12, 13, 14, ribbon muscles; 15, pharynx; 16, occipitalis; 17, 

 ear muscles; 18, trapezius; 19, 20, splenius; 21, levator scapulae; 22, 23, scalene; 24, 

 deltoid; 25, pectoralis major; 26, right platysma; 27, 28, lip muscles; 29, masseter; 

 30, buccinator. (Sappey.} 



Action of the three muscles. They draw the hyoid bone and 

 the larynx downward, and steady them. 



Nerves. Ninth cranial,, or hypoglossal. 



The digastric is another double-bellied muscle (Fig. 78). 



The posterior belly is attached to the mastoid process (medial surface) ; 

 the anterior belly to the under surface of the mandible close to the symphysis. 

 The intervening tendon glides through a loop of fascia connected with the 

 hyoid bone. 



Action. It draws the mandible downward, and opens the 

 mouth. (It is assisted by some other short muscles connecting the 

 mandible to the hyoid bone.) 



Nerves. Fifth and seventh cranial. 



