STRUCTURES OF THE NECK 361 



the three foramina mentioned elsewhere supraorbital, infra- 

 orbital and mental the three particularly sensitive spots in the 

 front of the face. 



Practical note. The tongue muscles and the floor of the mouth 

 (mylo-hyoid muscle) are both connected with the mandible. 

 Therefore, if the jaw be held forward and upward, it will control 

 the position of the tongue when the muscles are relaxed, as under 

 ether. Hence, the necessity for this precaution, to prevent the 

 tongue from falling back into the throat. 



FIG. 232. SUPERFICIAL VESSELS OF HEAD. 



THE NECK 



The skin of the back of the neck is very tough and the fascia 

 very dense. These facts account for the pain of inflammation 

 here, due to the consequent pressure upon the rather numerous 

 nerves, as in carbuncle. 



The spine of the seventh cervical vertebra is always easily felt. 

 This is the vertebra prominens. 



The two sterno-cleido-mastoid muscles are conspicuous at the 

 side of the neck, situated near each other at their origin, and di- 

 verging above. The thyroid cartilage of the larynx projects in 

 front the so-called Adam's apple. The external jugular vein runs 

 from behind the ear downward toward the middle of the clavicle, 

 and is covered by the pla'tysma muscle. It is sometimes selected 

 for the operation of "bleeding," or phlebotomy, and the incision 



