362 



ANATOMY AND PHYSIOLOGY 



to expose the vein is made across the muscle fibers, because by 

 their retraction the vessel is well uncovered (Fig. 76). 



The sternomastoid and trapezius are the muscles affected in the 

 commonest form of wry-neck or torticollis, which is usually due to 

 spasm of the muscles. 



THE TRIANGLES OF THE NECK 



These are spaces between certain muscles, as follows: In front 

 of ; the sterno-mastoid is an anterior triangle divided by the superior 



FIG. 233. TRIANGLES OF THE NECK. 



C, Carotid triangle; M, muscular triangle; O, occipital triangle; S, subclavian 

 triangle; D, digastric triangle. 



belly of the omo-hyoid into two, called the carotid and muscular 

 triangles ; behind the sterno-mastoid is a posterior triangle divided 

 by the inferior belly of the omo-hyoid into two, called the occipital 

 and subclavian triangles. 



In the nuscular triangle is the common carotid artery, with the 

 internal jugular vein on the lateral side of it, and the vagus nerve 

 behind them both. 



In the carotid triangle the same structures are found, but 



