550 



ANGIOLOGY 



The cervical portions of the common carotids resemble each other so closely 

 that one description will apply to both (Fig. 507). Each vessel passes obliquely 

 upward, from behind the sternoclavicular articulation, to the level of the upper 

 border of the thyroid cartilage, where it divides into the external and internal 

 carotid arteries. 





FIG. 507. Superficial dissection of the right side of the neck, showing the carotid and subclavian arteries. 



At the lower part of the neck the two common carotid arteries are separated 

 from each other by a very narrow interval which contains the trachea; but at the 

 upper part, the thyroid gland, the larynx and pharynx project forward between 

 the two vessels. The common carotid artery is contained in a sheath, which is 

 derived from the deep cervical fascia and encloses also the internal jugular vein 

 and vagus nerve, the vein lying lateral to the artery, and the nerve between the 

 artery and vein, on a plane posterior to both. On opening the sheath, each of 

 these three structures is seen to have a separate fibrous investment. 



