136 MUSCLE TISSUE 



The Sternomastoid. Origin, from anterior surface of 

 the sternum, inner third of upper surface of clavicle; 

 two portions meet and pass obliquely upward and 

 back across the lateral aspect of the neck to be inserted 

 into the anterior border and outer surface of the 

 mastoid portion of the temporal bone. 



Actions. The two muscles acting together bend the 

 head upon the neck. When only one muscle contracts 

 the head is drawn toward the shoulder of the same 

 side, at the same time the head is rotated, so that the 

 face is carried to the opposite side. When the head 

 is held firm by the other muscles the sternomastoid 

 acts as a muscle of respiration in forced breathing. 

 Nerve spinal accessory and deep branches of cervical 

 plexus. 



Depressors of the Hyoid Bone 



Ster nohy oid . Thy rohy oid . 



Sternothyroid. Omohyoid. 



The Elevators of the Hyoid Bone 



These muscles are situated at the inferior and lateral 

 aspect of the floor of the mouth, below the mandible. 

 They are covered by the deep cervical fascia of the 

 neck. 



Digastric. Mylohyoid. 



Stylohyoid. Geniohyoid. 



Deep Neck Muscles 



There are numerous neck muscles deeply located in 

 the neck; they assist to maintain the head erect and 

 also aid in flexing, extending, and rotating the head on 

 the spinal column. A description of these muscles will 

 not be given, as they cannot be properly understood 



