THE PLATYSMA MYOTDES. 



573 



articulation with the sternum ; from the lower end of this make 

 another cut outwards along the clavicle as far as the acromion and 

 reflect the piece of skin backwards towards the trapezius muscle. The 

 superficial fascia, which will then be brought into view, contains 

 the platysma ; and to see that muscle, it will be necessary to take 

 the subcutaneous laver from the surface of the fibres. 



Anterior belly of digastric. 

 Posterior belly of digastric. 



Anterior belly of omo-hyoid. 



Supraclavicular 

 triangle. 



Posterior belly of the omo-hyoid. 

 FIG. 209. DIAGRAM OF THE TRIANGLES OP THE NECK. 



The ANTERIOR TRIANGLE is made up of 



1. The sub-maxillary triangle. 



2. The carotid triangle. 



3. The muscular triangle. 



The POSTERIOR TRIANGLE is made up of 



1. The occipital triangle. 



2. The supraclavicular triangle. 



The PLATYSMA MYOIDES is a thin subcutaneous muscular layer, Platysma 

 which is now seen only in its posterior half. It is placed across the musele 

 side of the neck, and extends from the shoulder to the face. Its 

 fleshy fibres take origin from the skin and subcutaneous tissue over arises at 

 the clavicle and acromion, as well as from that covering the highest s 

 parts of the pectoral and deltoid muscles ; ascending through the 

 neck, the fibres are inserted into the jaw and the angle of the mouth, inserted 



into jaw 



