MUSCLES OF THE NECK. 861 



A. The Hyoid Bone. 



The body of the hyoid is a transverse bar of bone, deeply 

 placed between the rami of the mandible, and about midway 

 between the hinder end of the mandibular symphysis and the 

 angles of the jaw. 



The posterior comua of the hyoid are a pair of slender 

 rods of bone, about half an inch long, running backwards and 

 outwards from the outer angles of the body of the hyoid, 

 parallel- to the angles of the jaw. 



Determine the position and shape of the hyoid by feeling 

 with the finger. 



B. The Muscles of, the Neck. 



A few of the more prominent of the ventral muscles of the 

 neck are alone described here. 



Identify and carefully clean them. 



1. The sterno-mastoid muscles are a pair of narrow but 



strong muscular bands, which arise from the ante- 

 rior end of the sternum, close to the middle line, 

 and run obliquely forwards and outwards, across 

 the front of the neck, to be inserted into the mastoid 

 processes of the skull immediately behind the ears. 



Cut through the right sterno-mastoid close to its origin 

 from the sternum, and turn it forwards. Near its anterior 

 end, note, and carefully preserve, a branch of the spinal 

 accessory nerve, which enters the muscle on its inner side,' 

 about half an inch behind the angle of the jaw. 



2. The sterno-hyoid muscles are a pair of broad but thin 



muscular bands running along the ventral surface 

 of the neck. They arise from the dorsal surface of 

 the anterior end of the sternum, where the two are 

 fused, and run forwards along the neck. ■ A little 

 behind the angle of the jaw, the two muscles diverge 

 slightly from each other, and are inserted into the 

 bases of the postei:ior cornua of the hyoid. Their 

 hinder ends are covered by the sterno-mastoids. 



