484 MUSCLES OF ANTERIOR NECK. 



Function. To draw down the os-liyoides, pharynx, and 

 larynx. It is covered by the sternum, clavicle, and sterno- 

 mastoid muscle at its lower portion. 



The sterno-tliyroideus is situated beneath the last, and is 

 broader and shorter, being ribbon-like in its appearance. 

 It arises from the back part of the upper bone of the ster- 

 num and the cartilage of the first rib, ascends obliquely, 

 and is inserted into the ala of the thyroid cartilage, upon 

 its oblique line. 



Function. To draw down the larynx. It is covered by 

 the sterno-hyoid and mastoid muscles. 



The omo-liyoideus (w^oj, shoulder^) is situated obliquely 

 across the neck, and is a long, narrow, and double-bellied 

 muscle. It arises from the superior costa of the scapula, 

 posterior to its semi-lunar notch, and from the ligament of 

 this notch by a fleshy origin. It occasionally arises from 

 the acromial end of the clavicle, and base of the coracoid 

 process. It ascends above the clavicle and passes behind the 

 sterno mastoid muscle, where it becomes tendinous. After 

 this it again becomes fleshy and is inserted into the inferior 

 border of the os-hyoides, at the junction of its body and 

 cornu. 



Function. To draw the os-hyoides downward and back- 

 ward, and assist in deglutition. Its origin is concealed by 

 the trapezius; it crosses the carotid artery and internal 

 jugular vein, and its insertion is covered by the fascia and 

 integuments. 



The two sterno-mastoid muscles, with the omo-liyoid, and 

 the anterior edge of the trapezius, to be presently noticed, 

 form several triangles very important in a surgical point 

 of view, and recognizable in the living subject. 



The two sterno-mastoid muscles, coming together at the 

 sternum, form the apex of a large triangular space on the 

 front of the neck, the sides of which are formed by the diver- 

 gence of these same muscles, to the mastoid processes, while 

 the base of this triangle is above, and constituted by the 

 lower jaw. The median line of the neck divides this triangle 

 into two, called the anterior lateral triangles of the neck. 



