EXTERNAL CAROTID ARTERY. 269 



gastric nerve; and in front the sterno-thyroid, sterrio-hyoid, sterno- 

 mastoid, omo-hyoid, and platysma muscles, and the descendens noni 

 nerve. The left common carotid, in addition to the relations just 

 enumerated, which are common to both, is crossed near its com- 

 mencement by the left vena innominata ; it lies upon the trachea ; 

 then gets to its side, and is in relation with the oesophagus and tho- 

 racic duct : to facilitate the study of these relations, I have arranged 

 them in a" tabular form. 



Plan of relations of the Common Carotid Artery. 



In Front. 

 Platysma, 



Descendens noni nerve, 

 Omo-hyoid, 

 Sterno-mastoid, 

 Sterno-hyoid, 

 Sterno-thyroid. 



Externally. 

 Internal jugular vein, 

 Pneumogastric nerve. 



Common 

 Carotid Artery. 



Internally. 

 Trachea, 

 Larynx, 

 Recurrent laryngeal 



nerve. 



Behind. 

 Longus colli, 

 Rectus anticus major, 

 . Sympathetic, 

 Inferior thyroid artery, 

 Recurrent laryngeal nerve. 



Additional relations of the Left Common Carotid. 



In Front. Behind. Internally. Externally. 



Left vena innominata. Trachea, Arteria innominata, Pleura. 



Thoracic duct. (Esophagus. 



EXTERNAL CAROTID ARTERY. 



The External carotid artery ascends nearly perpendicularly from 

 opposite the upper border of the thyroid cartilage, to the space be- 

 tween the neck of the lower jaw and the meatus auditorius, where 

 it divides into the temporal and internal maxillary artery. 



Relations. In front it is crossed by the posterior belly of the 

 digastric us, stylo-hyoideus, and platysma myoides muscles; by the 

 lingual nerve near its origin; higher up it is situated in the sub- 

 stance of the parotid gland, and is crossed by the facial nerve. Be- 

 hind it is separated from the internal carotid by the stylo-pharyngeus 

 and stylo-glossus muscles, glosso-pharyngeal nerve, and part of the 

 parotid gland. 



