MUSCULAR SYSTEM OF THE RED HOWLING MONKEY 



27 



origin of the sternocleidomastoid, and a lower and deeper one for 

 that of the digastric. The fleshy fibers of the sternocleidomastoid 

 pass caudally, forward, and medially delimiting the anterior and 

 posterior cervical triangles. During its course over the neck the 

 muscle is contained within the investing layer of the cervical fascia 

 which is particularly resistant near the mandible and continuous 

 with the parotid sheath. The distal end of the muscle expands fan- 

 wise at the insertion. Its fleshy fibers attach on the upper and posterior 

 aspect of the medial two thirds of the clavicle, the sternoclavicular 

 capsule, and the upper and posterior surfaces of the sternal process. 

 The observations of Sirena (1871) coincide with mine. 



Nerve supply: The spinal accessory nerve, together with contri- 

 butions from C II and III. 



yi.H 



V ® 



Figure 9. — Mastoid and styloid regions (1, supramastoid crest; 2, premastoid crest; 3, 

 horizontal part of lambdoid crest (nuchal line); 4, descending part of the lambdoid crest 

 also called postmastoid crest; 5, separation between the sternocleidomastoid and digastric 

 areas; 6, horizontal ramus of postmastoid crest; 7, styloid region). 



275-199 O - 68 - 3 



