THE COMMON CAROTID ARTERIEH. 



483 



In the neck the two common carotids resemble each other so closely that one 

 description will apply to both. Each vessel passes obliquely upward from behind 

 the sterno-clavicular articulation to a level with the upper border of the thyroid 

 cartilage, opposite the fourth cervical vertebra, where it divides into the external 



FIG. 284. Plan of the 

 branches of the external 

 carotid. 



FIG. 283,-^Surgical anatomy of the arteries of the neck, showing the carotid and subclavian arteries. 



and internal carotid ; these names being derived from the distribution of the 

 arteries to the external parts of the head and face and to the internal parts of the 

 cranium and orbit respectively. 



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

 from each other by a small interval, which contains the trachea; but at the upper 

 part, the thyroid body, the larynx and pharynx project forward between the 

 two vessels, and give the appearance of their being placed farther back in this 

 situation. The common carotid artery is contained in a sheath derived from the 

 deep cervical fascia, which also encloses the internal jugular vein and pneumo- 

 gastric nerve, the vein lying on the outer side of the artery, and the nerve between 



