68 



THORAX 



half of the thorax of the same side ; and the left innominate 

 vein receives (a) the left superior intercostal vein, () some 

 pericardiac and thymic veins, and (c) the thoracic duct. 



Dissection. After the innominate veins and their tribu- 

 taries have been cleaned displace the left innominate upwards 



Spinal medulla 



Trachea 



CKsophagus 



4th thoracic vertebra 



Innominate artery 



Left common carotid 

 Left innominate vein 



L Manubrium sterni 



Synchondrosis 

 sternalis 



t pulmonary 

 artery 

 Pericardial cavity 



Left atrium 

 Aortic val\ e 



Body of sternum 



Right atrio- 

 ventricular valve 



Diaphragm 

 Descending aorta 



Xiphoid process 

 Liver 



FIG. 28. Sagittal section of the Thorax of an old man. The upper border 

 of the manubrium sterni and the bifurcation of the trachea are lower 

 than in the average adult. 



or downwards, or divide it, as may be necessary, and clean the 

 innominate artery from its origin from the arch of the aorta 

 to its bifurcation into the right subclavian and right common 

 carotid arteries. Next clean the left common carotid artery 

 and the left subclavian artery, taking care not to injure the four 

 nerves which descend between them, viz., the left phrenic nerve, 

 the inferior cervical cardiac branch of the left vagus, the superior 

 cervical cardiac branch of the left sympathetic trunk and the 

 left vagus nerve, all of which have been identified in an earlier 

 dissection (p. 35). When the three large branches of the arch 



