Mediastinum . 1 49 



border of the bone, to the upper limit of the right sterno- 

 clavicular articulation. Left common carotid, by a line 

 starting a little to the left of the preceding and terminat- 

 ing at the upper border of the left sterno-clavicular artic- 

 ulation. The left subclavian may be represented by a 

 line, which, beginning a little to the left of the origin of 

 the common carotid, i.e., nearer to the left border of the 

 sternum, is drawn upwards to a point, about half an inch 

 external to the left sterno-clavicular articulation, and 

 thence, with concavity downwards, to end a little to the 

 inner side of the middle of the clavicle. 



The Veins. The veins of the mediastina are the 

 left and right innominate, the superior and inferior venae 

 cavse, the azygos, the bronchial and the pulmonary veins. 

 The right innominate, about one inch in length, brings 

 the blood from the right upper extremity and from the 

 right side of the head and neck, from the region of the 

 right internal mammary artery, and, occasionally, from 

 the first and second intercostal spaces. It passes verti- 

 cally downwards from its origin, i.e., the junction of the 

 right internal jugular with the subclavian vein, to form 

 the superior vena cava bymniting with the left innominate 

 vein at the lower border of the first costal cartilage on the 

 right side. The left innominate, about two and a half 

 inches long, conveys the blood from the left upper limb, 

 left side of the head and neck, left internal mammary and 

 bronchial veins, and from the upper two or three left 

 intercostal spaces. It runs obliquely across the superior 

 mediastinum from the inner end of the left clavicle to the 

 lower border of the first cartilage on the right side, and 

 lies behind the first piece of the sternum and in front of 

 the large branches of the transverse aorta. There are no 

 valves in the innominate veins. In the foetus, and, rarely 

 in the adult, the left innominate empties, separately, into 



