476 



THE ARTERIES 



left pneumogastric nerve; and, slightly overlapping it, the edge of the left pleura 

 and lung (fig. 328). 



The variations in the origin of the left common carotid are given under VARIATIONS OP THK 

 Arch of the Aorta (page 471). 



THE COMMON CAROTID ARTERY IN THE NECK 



Tlie common carotid artery in the neck extends from the sterno-clavicular 

 articulation to the upper border of the thyroid cartilage on a level with the fourth 

 cervical vertebra where it divides into the external and internal carotid arteries. 

 A line drawn from the sterno-clavicular joint to the interval between the mastoid 

 process and the angle of the jaw would indicate its course. The artery is at first 



Fig. 328. — Scheme of the Relations of the Left Common Caeotid and Left 

 Subclavian Arteries within the Thorax. (Walsham.) 



I, just above origin ; II, just below level of steruo-clavicular joint. 



I 



LEFT RECURRENT 

 LARYSGEAL NERVE 



Left common carotid artery 

 Innominate artery 



CARDIAC NERVES 

 Right innominate vein 



Left subclavian artery 



LEFT PNEUMOGASTRIC 

 NER VE 



— Left innominate vein 

 Inferior thyroid veins 



REMAINS OF THYMUS GLAND 



5TEJ^NUT?1- 



II 



LEFT RECURRENT 

 LARYNGEAL NERVE 



Inferior thyroid veins \ 

 Innominate artery 



REMAINS OF THYMUS GLAND 



THORACIC DUCT 



Left subclavian artery 



LUNG AND PLEURA 



LEFT PNEUMOGASTRIC 



NER VE 

 Left common carotid artery 



- Left innominate vein 



Left Bterno-hyoid and 

 Left sterno-thyroid muscles 



deeply placed beneath the sterno-mastoid, sterno-hyoid, and sterno-thyroid 

 muscles, and at the level of the top of the sternum is only three-quarters of an inch 

 (2 cm.) distant from its fellow of the opposite side, and merely separated from it 

 by the trachea. As the carotid arteries run up the neck, however, tliey diverge in 

 the form of a V and become more superficial, though on a plane posterior to that 

 in which they lie at the root of the neck, and are separated from each other by the 

 larynx and pharynx. At their bifurcation they are about two inches and a quarter 

 (6 cm. ) apart. The common carotid is contained in a sheath of fascia common 

 to it and the internal jugular vein and pneumogastric nerve. The artery, vein, 

 and nerve, hoAvever, are not in contact, but separated from one another by fibrous 

 septa, which divide the common sheath into three conqiartments: one for the 

 artery, one for the vein, and one for the nerve. The vein, wliich is larger than 

 the artery, lies to the outer side, and somewhat overlaps the artery. The pneumo- 



