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COMMON CAROTID ARTERIES. 



The common carotid arteries (, the head,) arise, the right from 

 the bifurcation of the arteria innominata opposite the right sterno- 

 clavicular articulation, the left from the arch of the aorta. It follows, 

 therefore, that the right carotid is shorter than the left ; it is also more 

 anterior ; and, in consequence of proceeding from a branch instead of 

 from the main trunk, it is larger than its fellow. 



The Right common carotid artery (fig. 116, No. 5) ascends the neck 

 perpendicularly, from the right sterno-clavicular articulation to a level 

 with the upper border of the thyroid cartilage, where it divides into 

 the external and internal carotid. 



The Left common carotid (fig. 116, No. 11) passes somewhat ob- 

 liquely outwards from the arch of the aorta to the side of the neck, 

 and thence upwards to a level with the upper border of the thyroid 

 cartilage, where it divides like the right common carotid into the ex- 

 ternal and internal carotid. 



Relations, The right common carotid rests, first, upon the longus 

 colli muscle, then upon the rectus anticus major, the sympathetic 

 nerve being interposed. The inferior thyroid artery and recurrent 

 laryngeal nerve pass behind it at its lower part. To its inner side is 

 the trachea, recurrent laryngeal nerve, and larynx ; to its outer side, 

 and enclosed in the same sheath, the jugular vein and pneumogastric 

 nerve ; and in front the sterno-thyroid, sterno-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 commencement by the 

 left vena innominata ; it lies upon the trachea ; then gets to its side, 

 and is in relation with the resophagus and thoracic 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, 

 Stemo-hyoid, 

 Sterno-thyroid. 



Externally. I Internally. 



Internal jugular vein, Common Trachea, 



Pneumogastric nerve. Carotid Artery. Larynx, 



Recurrent laryngeal 

 nerve. 



Behind. 

 Longus colli, 

 Rectus anticus major, 

 Sympathetic, 

 Inferior thyroid artery, 

 Recurrent laryngeal nerve. 



