REGION OF THE CAROTID ARTERIES. 87 



sterno-mastoid, sterno-hyoid, sterno-thyroid, omo-hyoid, 

 descendeus noni, artery to sterno-mastoid, middle and 

 superior thyroid, lingual and facial, and anterior jugular 

 veins. 



Externally: Internal jugular vein, vagus nerve, and 

 lymphatics. 



Internally: Trachea, thyroid body, recurrent laryngeal 

 nerve, inferior thyroid artery, larynx, and pharynx. 



Behind: Prevertebral muscles, sympathetic, inferior 

 thyroid artery, and recurrent laryngeal nerve. 



The external carotid artery is given off from the main 

 trunk, usually opposite the upper border of the thyroid 

 cartilage; it is at first a little internal to, and in front of, 

 the internal carotid, and passes upwards and forwards, 

 and afterwards a little backwards, towards the angle of 

 the jaw. Up to the level of a line drawn from the mastoid 

 process to the hyoid bone the artery is superficial, but at 

 this point it gets deeper, being crossed by the ninth 

 nerve, the posterior belly of the digastric and stylo- 

 hyoid muscles and a plexus of veins; it then enters the 

 lower border of the parotid gland (vide Parotid Region). 



The branches of the external carotid are usually given 

 off in the following order: (1) superior thyroid; (2) 

 lingual ; (3) facial ; (4) occipital ; (5) posterior auricular ; 

 (6) ascending pharyngeal; terminating in the temporal 

 and internal maxillary. 



Relations of External Carotid. In front: Integument, 

 platysma, and fasciae, sterno-mastoid, hypoglossal nerve, 

 lingual and facial veins, posterior belly of digastric and 

 stylo-hyoid muscles, and parotid gland. 



Behind: Superior laryngeal nerve, styloid process, 

 stylo-glossus and stylo-pharyngeus muscles, glosso- 



